11351-Technicians Manual 1.pdf

PatternsTechnicians'manuall

Schools Council Integrated Science Project

The Schools Council Integrated Science Project was set up atChelsea College, London, from 1969 to 1975. The project teamhave developed their materials in association with many teachers,and have tested them in a wide range of schools.

OrganisersW.C. Hallas. Mowl

Team membersJ.I. BausorMrs. M.P. JarmanMiss B.A. LawesM.R.NiceD. Wimpenny

Northern Ireland coordinatorS.J. McGuffin

Patterns

Technicians'manual I

AuthorMike Nice

ContributorsDavid CrowhurstMalcolna FraserValerie Sheppard

Published for the Schools Councilby Longman and Penguin Books

Longman Group Limited, LondonPenguin Books Limited, Harmondsworth, Middlesexfor the Schools Council

© Schools Council Publications 1973

All rights reserved. No part of this publication may be reproduced,stored in a retrieval system or transmitted in any formor by any means - electronic, mechanical, photocopyingrecording or otherwise - without the prior permission of thecopyright owner.

First published 1973

ISBN 0 582 34005 5

Printed in Great Britain byCompton Printing Ltd, Aylesbury, Bucks.

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f,::. ./LJ

Contents

Preface vii

Classified list of equipmentIntroduction 1List of suppliers 3Apparatus 8Biological materials 22Chemicals 27Geological specimens 42Teaching aids 43Books for pupils and teachers 45

Preparation guideIntroduction 47Calendar 48Section 1 Patterns and problems 50Section 2 Galaxies, planets, and the Earth 56Section 3 Communities and populations 64Section 4 Looking at organisms 72Section 5 Cells and more cells 80Section 6 Molecules 84Section 7 Atoms and giant structures 108Section 8 The electron, ions and giant structures 120

Appendix 1 Notes on apparatus 138Appendix 2 Notes on biological materials 162Appendix 3 Chemical preparations 190Appendix 4 Hazards and precautions 200

Preface

The Technicians' manuals are primarily designed to enable schoollaboratory technicians to prepare the materials required for workdescribed in the Patterns sample scheme. The four manualsare ..complementary to the Teachers' guides and Pupils' manuals; all ofthese publications are required to follow the sample scheme.

Patterns demands a considerable degree of preparation ofmaterials, and by its very nature includes materials drawn from thevarious branches of science. Apart from apparatus required for classpractical sessions and demonstration lessons the scheme also uses avariety of teaching aids. The Technicians' manuals are designed toanswer three important questions:

What equipment is needed for the sample scheme?Where is the equipment used in the scheme?How is the equipment used?

The first of these questions is answered in the classified list ofequipment; the second and third are answered by the preparationguide. Both of these parts of the manual are in tabulated form, andare supplemented by appendixes which give further informationabout individual investigations and separate items of equipment.Each of the manuals is self contained, so that all the essentialinformation needed by technicians concerning the work in eachsection of the sample scheme will be found in the relevant volume.

vii

Classified list of equipment

IntroductionThis is a complete list of equipment required for the sample

scheme in Patterns 1, Building blocks.The list is divided into seven sections. The items which are

arranged alphabetically within each list are classified as follows:-

No stars Essential itemsOne star * Essential for optional/alternative workTwo stars ** Non-essential (or alternative) items

Quantities in each case are prefixed by the letters 'P' or 'T'.'P' denotes that the quantity specified is for ten pupils; and 'T',that the quantity is independent of pupil numbers (i.e. demonstrationitems).

The aim of the list is to ensure that schools have as littledifficulty as possible in obtaining items, The suppliers quoted are notexclusive, and their occurrence in the lists in no way implies thatthey are to be preferred to other sources. Suppliers are generallycoded with obvious codes of two or more letters. The addresses ofsuppliers are to be found in the list of suppliers at the beginning ofthe list of equipment. Where no supplier is specified in theappropriate column of the lists, the items are generally availablefrom scientific equipment supply companies.

The code LS means local source. This term is used to show thatitems can be obtained in local shops, or from the environment, orare usually available within schools.

Patterns does not use a system of item numbers. Whereappropriate, Nuffield numbers are included to aid identificationof particular items.

It is not intended that schools should feel obliged to purchase allthe items in the lists (not even the 'essential' ones). Most schoolswill already contain apparatus which, if not exactly that specified inthese lists, will suffice. Several items have been difficult to specifyexactly, in particular low tension electrical supplies. While it may

be desirable for each working group to have its own supply unit,this system may be too expensive to buy or some other system mayalready be in use. Providing the experiments can be accomplished itmatters not whether the supply is in the form of individual packs,accumulators, or even a common 1.t. a~c./d.c. system.

The technician is assumed to have appropriate tools of the tradeand these are not included in the apparatus list unless they arespecifically required for a particular piece of work, e.g. a pair ofpliers for the bromine diffusion experiment.

2

List of suppliersThe list is divided into two sections. In the first part are the suppliersof apparatus, chemicals, biological and geological materials. In thesecond part are the suppliers of teaching aids and associatedmaterials.

The suppliers are listed alphabetically, with codes takingprecedence over names. In general the addresses of publishing housesare not included in the list.

The following additional codes have been used in the Manual,but the addresses are not included in the list of suppliers:IS - Schools Council Integrated Science, Longman/PenguinLPT - Longmans Physics Topics, LongmanLS - Local SourceNAB - Nuffield Advanced Science Biology, PenguinNB - Nuffield O-level Biology, Longman/PenguinNC - Nuffield O-level Chemistry, Longman/PenguinNMM - Nuffield Mathematics Modules, MurrayNP - Nuffield O-level Physics, Longman/PenguinNSS - Nuffield Secondary Science, Longman/PenguinSCPT - Schools Council Project Technology, Heinemann

Part 1

Code Supplier Products supplied

AF Aluminium Federation, Kit, information60 Calthorp Road, Five Ways,

. Birmingham 15

A.R. Horwell Ltd, Polypropylene beakers,2 Grangeway, Kilburn High Road, hypodermic syringesLondonNW6

BDH The British Drug Houses Ltd, Chemicals, first aidBDH Laboratory Chemicals Division, chartPoole, Dorset

Belgrave (Mercury) Ltd, Mercury cleaning,5 Belgrave Gardens, St John's Wood, mercury supplyLondonNW8

BF British Steel Federation Training Dept, Tillich blocks (woodSteel House, Tothill Street, cubes 10 mmXLondon SWI 10 mmX 10 mm)

BOC The British Oxygen Co. Ltd, Gas cylinders and(Head Office), Hammersmith House, bookletLondon W6

3


CEP C.E.Payne Ltd, Disposable Petri6 Ively Road, Clapham, dishes and otherLondon SW4 OHS apparatusChemical Concentrates Ltd, RBS 25 (cleaning41 Webbs Road, London SWll solution)

DES Department of Education and Science, Barley with albinoLaboratories, Ivy Farm, Knockholt, mutantSevenoaks, Kent.

EA E.J. Arnold & Son Ltd, Tillich blocks (woodButterley Street, cubes 10 mm XLeeds 10 10 mmX 10 mm)

ED E. Dixon & Sons Ltd, Mouse diet 'F'Agricultural Merchants, Ware,Hertfordshire

ES E.S. Perry Ltd, Centicube (plasticOsmiroid Works, Gosport, interlocking cubes,Hampshire 10 mm X 10 mm X

10 mm X 1 g)Fisons Scientific Apparatus, Mercury cleaningBishop Meadow Road, Loughborough, apparatusLeicestershire LEll ORG

GG Griffin & George Ltd, General scientificEaling Road, Alperton, Wernbley, equipmentMiddlesex

GG Griffin & George Ltd, Biological materials(formerly P.K. Outt & Co. Ltd,),Lavender Hill, Tonbridge, Kent

GH Gerrard & Haig Ltd, Biological suppliesGerrard House, Worthing Road,East Preston, Sussex.Halsey Ltd, Grolux fluorescentWyfold Road, Fulham, London SW6 tubes

HW Hopkin & Williams Ltd, ChemicalsFreshwater Road, Chadwell Heath, EssexP.O. Box 1, Romford, Essex RMIIHA

JL Jencons Ltd, Glassware and otherMark Road, Hemel Hempstead, apparatusHertfordshire

MB May & Baker Ltd, Chemicals, chartsDagenham, Essex RMIO 7XS

4


MLI Morris Laboratory Instruments Ltd, Physical science96-8 High Street, Putney , equipmentLondon SW15 lRD

Oxoid Ltd, MicrobiologicalSouthwark Bridge Road, supplies,Mouse dietLondon SEI 41 B

PH Philip Harris Ltd, General scientificLudgate Hill, Birmingham 3 equipment

PH Philip Harris Ltd, Biological materialsHarris Biological Supplies Ltd,Weston-Super-Mare, Somerset

RP R.F .D. Parkinson & Co. Ltd, IS kit of rocksDoulting, Shepton Mallet, Somerset Geological specimens.

RS RS Components Ltd, Electrical components(Radiospares)P.O. Box 427, 13-17 Epworth Street,London EC2

SC The Ship Carbon Co. of Great Britain Ltd, Graphite electrodesChadwell Works, Grove Road,Chadwell Heath, Essex

Steralin Ltd, Disposable Petri12-14 Hill Rise,Richmond dishesSurrey

5

Part 2


Batchelors Ltd., BookletsWadsley Bridge, Sheffield, S6 ING

BSC British Steei Corporation, Charts and information33 Grosvenor Place, London SWI

BT British Transport Films, FilmMelbury House, Melbury Terrace,LondonNWI

CCHE Central Council for Health Education, Charts and booklets onTavistock House, Tavistock Square, teeth and dental careLorrdon WCI

EB Encyclopaedia Britannica Ltd, FilmDorland House, Instructional MaterialDivision, 18-20 Regent Street,London WI

Gateway Educational Films Ltd, ' Film loops470-72 Green Lanes, Palmers Green,London N13

ICI Imperial Chemical Industries Ltd, Charts and informationEducation Division, Millbank,London SWI

ICI Imperial Chemical Industries Ltd, InformationFibres Division, Harrogate,Yorkshire

ICI Imperial Chemical Industries Ltd, InformationPlastics Division,Welwyn Garden City, Hertfordshire

ID Industrial Diamond Information Bureau, Booklet and charts7 Rolls Building, Fetter Lane,London EC4

IN International Nickel (Mond) Co. Ltd, Charts and informationThames House, Millbank, London SWIMacmillan, Film loopsBrunel Road, Basingstoke, Hampshire

MO Microslides Oxford Ltd, Photornicro-7 Little Clarendon Street, Oxford transparencies

NIAB National Institute of Agricultural Farmers' Leaflet No.8Botany, Huntingdon Road, Cambridge

6

Code Supplier Products supplied'

PH Philip Harris Ltd, Photomicro-Harris Biological Supplies Ltd, transparen ciesWeston-Super-Mare, Somerset

Rank Film Library, FilmP.O. Box 70, Great West Road,Brentford, Middlesex

Shell International Oil Co. Ltd, BookletsShell Centre, London SEl

Smedley's Ltd, BookletsWhyteleaf, Surrey

SW S.W. Optical Instruments Ltd, Photomicro-Southwick, Trowbridge, Wiltshire transparencies

Thorn Lighting Ltd, Information on GroluxThorn House, Upper St Martin's Lane, fluorescent tubesLondon WC2

Unilever Ltd, Charts and informationUnilever House, Blackfriars,LondonEC4

7

Apparatus

Item Specification Quantity Notes Source

Aluminium block *Sets of 5 sizes P 2 sets NP item 1Materials Kit LSmay be useful

Aluminium kit *"Investigating T 1 Kit For 7.7 AFthe propertiesof aluminiumalloys

Ammeter Pupil meters, P5 For"'S.7 and s.n.moving coil, d.c. Multimeters may be used asrange 0-1 A alternative to separate meters,

or multirange meters withshunts

Aquarium **Plastic, 300 mm T upto Useful for several purposes.X 200 mmX 5 Alternative: glass aquaria200mmapproximately

Asbestos paper Roll, 3 m long T 1 roll For Ji..2.7, Ji..7.10 and Ji..7.19 GGPHapproximately Cut to 50 mm X 30 mm strips

Autoclave Must be able to T1 For culture media. Alternative:withstand domestic pressure cookerpressure of lOSN m-2 (15 p.s.i.).Portable

Balance *Balance with T1 ForL::.6.13beam

Chemical, e.g. top T1 Alternatives: any balances willpan, 3-4 place suffice, but more will be

required if not quickRough weighing, T1 weighing.e.g. top pan, 1place

Balloon T 3-4 For discussion after 6.1- LS

Barometer tube ** T 1-2 For discussion after 6.9

Beaker Glass, 50 cm3 P5 For 3.5Glass, squat P5 Soda glass beakers willform, 100 cm3 suffice but hard glass

250 cm-' P5 (e.g. Pyrex) gives better400 cm3 P5 service

1000 cm3 P5

8


Bosshead P 10 For use with retort stands andclamps

Bottle Orange juice T 10 For Drosophila cultures LS(milk) bottles,1/3-% pint

Bowl **Washing-up type, P3 Alternative to trough LSblack polythene

Boyle's Law Fitted with Tl For 6.7 GGPHapparatus Bourdon gauge,

e.g. NP item 109

Bromine NP item 8 Tl For 6.1c - see GGPHdiffusion kit Appendix 1

Brush Soft hair: P5 For"'3.7 and~6.12diameter ofmount Tl For 3.8approximately3mm

Bucket Plastic, 10 000 P2-3 For 6.15 LSem3 (2 gallons)

Bung Cork, to fit 16 mm P5 For"'6.18diameter tubeCork, to fit 20 mm T2 For 6.1bdiameter tubeRubber, solid, to Tl For "'6.10fit 150 X 25 mmtest tube

*Rubber, to fit T 1-2 For 66.13Visking tubing

**Rubber, 1 hole, Tl For "'6.3to fit porous potRubber,1 hole, P5 For"'7.19to fit 16 mmtest tube

**Rubber, 1 hole, T5 For etheriser constructionto fit 25 mmtube

*Rubber, 1 hole, T 1-2 For66.13to fit Viskingtubing

Bunsen burner Macro P5

9


Cage *Cambridge style T6-12 For mice, see 64.13and Appendix 2 'Mice'

Can With lever top P5 For~6.9, e.g. treacle tinlid, at least100mmdiameter

Candle Wax, 150 mm X Tl ForA8.6 LS20mmapproximately

Card Thin cardboard For template making and LSmodel making

Centrifuge ** Tl See Appendix 2 'Paramecium'

Centrifuge tube **To fit T 1 setcentrifuge

Chalk Soft blackboard PI pack ForA6.3 LS

Circuit Board Worcester type, P5 For 7.1 andA8.7NP item 52 Connectors also required

Clamp P 10 For use with retort standsand bossheads

Clip *Screw type, e.g. T 1-2 For~.13Hoffman

Cloth Minimum size, P 5 of For electrostatics experiments GGPH150 mm square each Section 8 LSwoollen (flannel)cotton, silk,nylon, etc.

Compact light Tungsten halide Tl For~8.6source lamp, 12 V 100 W,

NP item 21

Compass Plotting P5 Used on field trips

Compasses Drawing P 5 pairs For model making LS

Connecting leads Stranded, PVC P20 Made from wire bought as a GGPHinsulated copper reel RSwire to take 2-5A, 0.5-1 m long

Cork mats ** P 1-2 For Drosophila handling -see Appendix 2 'Drosophila'

10

Item Specification .Quantity Notes Source

Cotton wool Absorbent T 1 pack For 6.1bNon-absorbent PI pack For .6.4.6, used as plugs

Coverglass 16mm diameter PI pack For use with micro-slides(% oz)

Crocodile clip To fit 4 mm P % gross Mainly used with connectingplugs and circuit leadsboard terminals

Crucible 8 ern>, porcelain T2-4 For 2.4

Crystallising dish **Minimum diameter P5 For 6.19 - used with dialysers100 mm, capacity375 cm3

Delivery tube Bent at 90° to P5 ForA6.l8. Home made fromform length 5-6 mm soda glass tubing180 mm X50mmBent at 90° to Tl For 6.26. Made from 8 mm tubingform "length75 mmX50mmStraight, 70 mm P5 ForA7.l9long

**Straight, 200 mm Tl For A63long

Desiccator Minimum internal Tl For 2.4. Vacuum type andiameter at top. advantage200mm

Dialyser **Graham type P5 For 6.19. Alternative is Visking GGPHtubing

Diamond Structure PI For ~7 .5. Alternative- GGKit polystyrene spheres, see

Appendix 1 'Molecularmodels'

Diffraction grid Nuffield type P class For 7.1 GGset

Dissecting board ** Tl ForA6.2l

Dissecting **Including pins T 1 set ForA6.21instruments

Drill Electric, 2 speed Tl For filing chalk for A 6.3 GGLS

11


Drill stand Appropriate to Tl GGLSelectric drill

Drinking straw Waxed paper type PI pack For producing smoke for'" 6.4

Dropper bottle Glass, 100-250 T 50-100 For dispensing reagents,cm3, preferably indicators, etc.fitted Withdropper pipettes

Dropper (teat) Glass with rubber P 10 Can be home made from 8 mmpipette or plastic teat overall diameter soda glass

tubing

Dry cell 1.5 V (U2 type) P 50 For use with circuit boards

Eih.t. supply To give variable Tl For discussion after 8.5 GGPHd.c. supply up to and forA8.65 kV. NP item 14

Electrode Graphite, 200 mm 1 pack ForA:8.7, 8.8,"'8.9,"'8.10- GGSCX5mm of 50 see Appendix 1

'Electrolysis cells'

Electrolysis cell Nuffield type P5 Used in 2.6, "'2.7b and 6.25See Appendix 1 forconstruction details

Electrophorus discs 150 mm diameter T2 For 8.5 andA8.6 GGPHmetal discs oninsulating handleNP item 65

Electroscope **Gold leaf Tl For 8.2 GGPHelectroscope

Etheriser **With side arm P 1-2 For Drosophila work. GHPHAlternative: made withspecimen tube and filterfunnel see Appendix 2'Drosophila'

Evaporating basin 75 em3 porcelain P5 For 2.11 .•.7.3 and 8.16

File Flat Tl For filing chalk for'" 6.3 LS

Flame test wire Nichrome wire P5 For 6.19 and"'7.3 - see GGin holder Appendix 1

12


Flask Conical, 100 em3 P5 For 6.24 and 7.7*Conical, 250 cm3 T 1-2 For'" 3.7b Paramecium

cultureRound bottom100 cm3 P5 For'" 4.6Round bottom500 cm3 P5 ForA4.6

Forcemeter O-lON P5 For 1.9, "'1.10 and"'5.4. GGAlso called dynamometer orspring balance

*Personal weighing T1 For D. .•. 4.5 Bathroom scales GGmachine converted to read in newtons0-1250 N X 5 N - see Appendix 1

'Personal weighing machine'

Forceps Coarse, P 5 pairs For 5.1 and "'5.2polypropylene

**Fine points, P 5 pairsstraight

Fume cupboard T1

Funnel **Glass, dropping T1 For "'6.10Glass, filter, P5 For 2.11,'" 7.3,8.1675 mm diameterGlass separating T1 For 2.11100 cm3

*Glass, thistle T 1-2 For D.6.11250 mm stemGlass, thistle T1 For 6.26. The stem needs300 mm stem to be bent into a U

(2 X 90°)**Polypropylene, P 1-2 For etheriser construction -

filter, 75 mm see Appendix 2 'Drosophila'diameter

Galvanometer Internal light T1 For 8.5 and 8.8 GGPHbeam, highresistance (spotgalvanometer)e.g. Scalamp

Gas jar 250 mm tall, P 10 For 6.1awith cover

Gauze Iron, with P5 Used with tripodsasbestos centre,100-150 mmsquare

13

Item Specifica tion Quantity Notes Source

G-clamp ** T1 To clamp retort stand to benchinA5.4

Glass block *Sets of 5 sizes P 2 sets NP item 1 Materials Kit may LSbe useful

Glass rod **200 mm X 5 mm T 1-2 ForAS.4diameter

Glass tube **200 mm X 5 mm T 1-2 ForAS.4diameter100mmX8 mm P 10-20 For A6.3outside diameter1 mX20mm T 1-2 For 6.1binside diameter

Hammer ** T1 For cleaving calcite inA-8.18 LS

Hand lens X 8 or X 10, P 5-10folding

Hypodermic Plastic,2 cm3 P5 Needle also ~equiredsyringe disposable

Plastic, 10 em3 P5 For AI. 7 andA6.20disposable

Incubator Oven type with T 1-4 It is an advantage to havefine several, as different culturethermostatic temperatures are thencontrol possible

Inoculating loop *Nichrome wire P5 For 64.10 - see Appendix 1 GGin holder 'Flame test wires'

Iron(steel) block *Sets of 5 sizes P 2 sets For 61.8 NP item I LSMaterials Kit may be useful

Jar **Jam jar, 500 g T4 To contain powders forA 1.3 LScapacityKilner type, T6 For Tribolium culture see 3.8 GGLS500 g capacity and Appendix 2 'Tribolium'

Jet Glass,straight T 1-2 To deliver carbon dioxide in A6.3GG PHHome made from glass tubingsee Appendix 1 'Jets'

*Glass capillary, T 1-2 For 66.1325 mm limbs at900

14


Lamp MES bulb and P5 For 7.1 and.&8.7holder, 1.25 V0.25 ATungsten Tl Used with translucent LSfilament, 240 V screen in 6.1 and .&6.9.60 W with holder, Microscope lamp willshade and stand suffice

Lath Wooden, 1 mX P20 For making quadrats LS25 mmX 10 mm for 3.5b

L.t. supply Variable supply P5 NP item 59 is recommended,0-24 V a.c./d.c. but a built in Lt. supply or

tapped 12 V accumulators maybe used

Mass **Slotted masses on P 5 sets Alternative to 0-10 Nhangers, ION X forcemeter for .&1.10IN(1 kg X 100 g)

Mat Approximately P5 Used mainly with Bunsen LS0.3-0.5 mX burners - Appendix 10.3-0.5 mhardboard

Measuring cylinder *Glass, 25 or P5 For 8.16100 cm3

500 cm3 T 1-2 For .&4.6

Measuring tape **Approximately T1 Useful as alternative to metre20m rules

Membrane *Cel1ulose, e.g. P 5-10 For66.11c LSjam jar covers

Mercury tray .** Tl For.&6.9

Mercury trough ** T1 For .&6.9

Metre rule P5

Microscope Monocular, with P5low and high'power objectives.Must be capableof use withsmoke cells

**Binocular (stereo) T1 Useful for identifyingto magnify to organismsX40

15


Microscope lamp P5 Required if microscopes haveno built in light source

Microslide P 10+ Minimum number given, buy bythe Yzgross pack

Mole kit PI kit Used in 7.12,7.13,7.14,7.15 GGand 7.16 - see Appendix 1for details

Mortar and 100 mm external P5 Used in 6.24,1..7.4 and 1..7.22pestle diameter

Mounted needle P 10 Used inI..3.7, 4.1, 5.1,1..5.2.Needle holders may be usedfor flame test wires

Muslin Butter muslin T Yz-1 m For making powder LSor stockinet sprinklers, plugs for Drosophilaetc. culture bottles, and covers for

Tribolium culture bottles

Newspaper * Supply For~4.5 LS

Nylon Monofilament P 5 reels For electrostatics suspension GGPHin 25 m reels for 8.1, 8.2,1..8.3 and 8.5 LS

Objects Small objects Large For 1..3.7a LSsuch as beads numberor matchsticks

Oil film kit NP item 7 can be PI kit For 6.15 - see Appendix 1used for details

Oven Thermostatically T 1-2 Incubator typecontrolled, range0-350°C +

Paper clip T 1 pack For A.6.20and 6.24 LS

Paper Filter, Grade 1 P 2-3discs, 125 mm packsFilter, Grade 1 P 2-3 For chromatography andsquares sheets irrigating micro slides

Filter, grade 3 T 1 pack see Appendix 2 'Drosophila'discs, 125 mmGraph, metric P Yz ream LS

*Graph, log-lin PlO Forl..3.7d LS(logarithmic and sheetslinear scales - of eachsemi-logarithmic)

16


Paper Squared T4-6 For chart construction LSsheets for 3.4

Petri dish Plastic, disposable P 100+ Steralin require a minimum CEPGG90 mm diameter order of 500 PH

Steralin

Photographic Glass, 35 mm T 1-2 For ...s.17 LStransparency slide square

Pipe clay triangle Approximately T 1-2 For 2.450 mm side length

Pipe cleaner PI roll For. 7.S for model making. GGPackets may be purchased locally

Pipette Glass, 25 em3 Tl For .8.9

Plant pot 100 mm diameter P 20-30 For. 4.11. Clay pots preferred LS125 mm diameter T6-12 Advance preparation for 9.1 LS180 mm diameter T9-18 Patterns 2. Clay pots preferred

Alternative - seed trays

Plastic tubing PVC, 100 mm X P5-10 For .6.3 GGGH8 mm internaldiameter

Pliers T 1 pair For crushing bromine capsules LSin 6.1c

Polystyrene spheres 25 mm diameter P 200 For details of modelling with GGPHmade up polystyrene spheres see

**25 mm diameter P 150 Appendix 1loose 'Molecular models'50 mm diameter T 250made up

Polythene strip *HDPE - high P5 For.6.i. 6.16 GGdensity polythene

*LDPE -low P5 For 6..6.16 GGdensity polythene

Pooter ** P5 Home made using specimentubes - see Appendix 2'Tribolium'

Porous pot ** T 1-2 For .6.3

Propagator ** Tl Alternative to greenhouse - seeAppendix 1

17


Pump Filter type, water T1 For 6.26operatedFoot pump and T1 For 6.7, used with Boyle'sadaptor law apparatus

**Vacuum! T1 For discussion following 6.1 GGcompression

Razor blade **Safety (hard T2-4 For calcite cleavage inA8.18 LSbacked) singleedged

Refrigerator With ice making T1(freezer)compartment

Retort stand P 10

Rheostat 10-15 n P5 For 8.11 GGPH

Rod or strip Examples: brass, P5 For electrostatics - see GGPHcellulose acetate, Section 8 LScopper, ebonite,glass, polystyrene,polythene, PVC,wood

Rubber band 6-12 mm wide Supply For 1.9,A1.10,66.11c,66.13 LSand assorted sizes andA6.20

Rubber cord 6 mm square or psX For 1.9 GGPHround section S50mm IS

Rubber gloves Household or T 1-2 pairs GGLSsurgical type

Rubber tubing 'Standard' 6 mm PS For connecting apparatusinternal diameterX 0.3-0.5 m

Rule Plastic, See 4.1transparent, withmm scale, e.g.oil film kitgraticule or selfadhesive tape(e.g. Scalafix)300 mm (1 foot) P 10 LS

Safety goggles ** T 1 pair For A5.4 GGPH

18


Safety screen Perspex or safety T 1-2 For 2.4,"-5.4 and 6.26 GGPHglass,750 mm X 600 mmapproximately

Seed tray *Plastic or wood, P2-4 For!::J;.8.20360 mm X 220 mmXSOmmapproximately

Self adhesive tape Transparent, P2-4 LSplastic, e.g. rollsSellotape

Sieve 1 mm aperture P 2-3 For sieving Tribolium LS(mesh - BS 16), culturese.g. wire mesh teastrainers

Skewer **Meat type P 10 Alternative to wooden stakes LSfor 3.Sb

Smoke cell Whitley Bay type P5 For "-6.4NP item 29

Spatula Nickel or P5stainless steel

Specimen tube 150 mm X 25 mm T 50 Various uses including GGstraight sided etheriser, pooter and sprinkler

construction

Spectroscope Direct vision P5 For "- 7.3 GGMLIPH

Sphere Table tennis ball Tl For 8.5 - alternative:with conducting metallised polystyrene sphere.surface on nylon Use Aquadag not aluminiumsuspension paint, if home made

Stake Wooden, 150 mm P 10 Alternative is meat skewer for LSlong 3.5bapproximately

Stirring rod Glass P5 Home made from glass rod

Stirrup Stirrup of wire P5 For electrostatics experiments8.1, 8.2 and"-8.3. Home made

Stopclock Mechanical P5 Alternatives: stop watches,timer wrist watches with large seconds

hand, or 1 large timer (e.g. sportstraining clock)

19


String Fine (not PI ball For 1.9 LSmechanics cord)Garden twine PI ball For 3.5b LS(sisal) 200 mball

Switch Contact key (push P5 For use with circuit boards GGswitch)

Test tube 75 mm X 12 mm P20 For .6.18 andA6.20. It issuggested that all tubes shouldbe hard glass (e.g. Pyrex) asthey give better service thansoda glass

100 mmX 16 mm P 5-10

125 mmX16 mm P 15

125 mmX16 mm P5 ForA7.19combustion type,with small holeat rounded end125 mmX16 mm P5 ForA6.18 and 6.26with side arm150 mmX25 mm P 5-10

Test tube holder P5 For 6.24,A7.4, 7.21 and A7.22

Thermometer -10 to -no'c, P 10 For 44.6,A 6,20, and 6.26300 mm long0-360°C P5 ForA6.18

Thread Cotton P 1 reel For 66.13 andA6.20 LS

Three dimensional NP item 11 Tl For A 6.8. A motor and cam arekinetic model kit required if the model has not

one built in

Tile White spotting P5 ForA6.20plastic orceramic

Tongs Crucible tongs, P 5 pairs200 mmlong

Toothpicks Wooden P 1-2 For model making LS(cocktail sticks) packs

20


Translucent screen 1 mXO.7 m Tl For 6.1c, .6.9, and .8.6approximately,NP item 46/1

Tripod P5

Trough Polythene, P3 For 3.4. Alternative:300 mm X 200 mm washing-up bowlX 100 mmapproximately,black

Two dimensional PI kit See Appendix 1 for details.kinetic theory kit NP item 12 may help.

U-tube Approximately T1 For 6.26100 cm-'

Van de Graaff NP item 60/1 T1 ForL-8.4 and 8.5generator and 60/2

(accessories)

Visking tubing Cellulose dialysis P 15 ForL-6.13 and.6.6.20 GGPHtube, 14 mmdiameter X150 mm length

Watch glass Hard glass (e.g. P5 For .6.18, 6.24, .7.3 and 8.19Pyrexjdllmmdiameter

*Solid; maximum P5 For A3.7b40mmX40mm(embryo cup)

Water bath **500 cm3 P5 For .6.20. Alternative:400 ern3 beaker

Wax pencil e.g. Chinagraph P5 For 3.4,.4.6 and.6.20. Forlabelling glass and plastic

Wire Bare copper, PI-2m For 7.7b22 s.w.g.

Wood block *Sets of 5 sizes P 2 sets NP item 1Materials Kit LSmay be useful. The blocksmust all be of the same typeof wood

Wooden cube 10 X 10 X 10 mm P 160 For 4.3. Alternative: Centicube BFEAe.g. Tillich blocks plastic interlocking, 1 cm3 X 1 g ES

W -tube 50-100 cm3 T1 For ~.9. Alternative is U-tube GG

21

Biological materials

This list contains the biological materials which are suggested inthe sample scheme. They are by no means exclusive and manyalternatives exist which would be equally suitable for the worksuggested. To this extent, then, all the materials in the list couldbe regarded as optional.

Specimens are classified according to common names, butlatinised names are also given. Where no common name exists onlythe latinised version is used.

Item Quantity Notes Source

Agar T 100-200 g Powder for making culture media.Blackened for "'4.11, glycerol nutrientfor .64.1O,plain nutrient for .64.10. Alsofor Drosophila culture medium. Nutrientagar tablets or ready mixed powder canalso be used for .64.10 - see Appendix 2'Agars and broths'

Amoeba T 1 culture Live for A5.2 - see Appendix 2

Barley seeds T 1 pack **Alternative to tobacco, must contain DESGGalbino mutant for "'4.11 - Xantha PH

T 250 g advance preparation for 9.1 Patterns 2 LS

Black treacle (see molasses) T 100 cm3 **Alternative to soft brown sugar, for LSDrosophila culture medium

Canadian pondweed Supply Suggested for 5.1. Culture in GHLS(Elodea canadensis) freshwater aquarium

Charlock, seeds T 10+ g **Advance preparation for 9.1, Patterns 2. LS[Synapis arvensis) Suggested for growing in competition

with barley. Alternative to mustard.Collect from environment

Coleus sp. Supply Suggested for 4.9 - see Appendix 2'Clones'

Compost, potting T25 kg For 4.9, e.g. John Innes No.1. LSBuy in bulk

Compost, seed T 25 kg **For "'4.11. Advance preparation for 9.1 LSPatterns 2. Buy in bulk. Alternativepotting compost

Dandelion Supply Suggested for 4.9 - see Appendix 2 LS

(Taraxacum officinale ) 'Clones'

22


Duckweed (Lemna sp) Supply For 8.19. Stock culture can be kept in LSa freshwater aquarium

Flour beetle, wild type 1 culture **ForA3.7 Either T. castaneum or GGGH(Tribolium castaneum) of each T. confusum will suffice. PH[Tribolium confusum) species For 3.8 both species are required - see

Appendix 2 for culture details

Fruit fly, wild type 1 culture ForJ..3.7 - see Appendix 2 for culture GGGH(Drosophila melanogaster) details PH

Fruit fly, containing 1 culture *For 4.9 GGGHreadily observable mutant PHcharacteristics, e.g. whiteeye or short wing

Gerbil T1 **Suggested organism for L-A4.5 if GHLSavailable

Grass seed T 500 g **Vsed to grow patches of turf in seed LSboxes for L-A8.20

Hamster T1 **Suggested organism for .6.6.4.5if available LS

Hay Supply See Appendix 2 'Mice'. Buy in bulk LS

Hay infusion T 1 infusion Suggested culture medium forParamecium - see Appendix 2

Leaf mould Supply In addition to mud from the. margin LSof a pond for 3.4

Meat extract T 10 g **For making nutrient agars, e.g. Brand's LSEssence, as alternative: nutrient agartablets or powder

Mouse, Jan strain T 1 pair *Breeding pair of unrelated mice for PH6 4.13 -see Appendix 2 for culturedetails. Also suggested organism forL-A4.5

Mouse food Supply *Rat cake pellets from pet shops, or EDGGMouse diet F from E Dixon, or Oxoid GHLS41B diet. Buy in bulk. E. Dixon suppliesin 25 kg (Ih cwt) sacks.

Mud Supply Dried mud from the edge of a pond for LS3.4

Mustard, seeds T 10+ g **Advance preparation for 9.l,Patterns 2. LS(white mustard - Suggested for growing in competitionSynapis alba) with barley. Alternatives are charlock or

poppy. Collect from environment

23


Oatmeal (breakfast oats) T 1 packet For Drosophila culture medium LS

Onion, red skinned variety P 2-3 bulbs **For 5.1 andD.6.12, alternative to rhubarb LS

Paramecium caudatum T 1 culture For.6.3.7b and 4.1 - see Appendix 2 GGGHfor culture details PH

Pea P 10-20 g *For66.14 a selection of peas preserved LSby different methods, e.g. canned(garden and processed), dried (split),fresh, frozen, freeze dried (Batchelor'sSurprise)

Peat Supply *For mouse culture, buy in bulk LS

Peptone T 50-100 g **For preparation of nutrient agar. BDHAlternative: nutrient agar tablets orpowder

Photographic Generally preferred to prepared GGGHtransparencies microslides which can be used as MOPH

alternatives SWT 1 of Suggested items for 5.3.

each bone, longitudinal and transverse sections;cheek cells (squamous epithelium); leafepidermis and cuticle, vertical section;nerve, transverse section;nerve cell showing axon; sperm; tendon,longitudinal section; xylem tissue,longitudinal and transverse sections;

Pond water, boiled Supply For 3.4 and 8.19, from pond known to LSand filtered grow Lemna

Poppy, seeds T 5-10 g **Advance preparation for 9.1, Patterns 2. LS(Papaver sp.) Suggested for growing in competition

with barley.Alternative to mustard.Collect from environment

Prepared microslides T 1 of each Photographic transparencies can beused as alternatives.

P5 For 4.1: any slide with a smallorganism

P2-3 For 5.1: cartilage; gut, transverse section;of each red blood cells

P5 For .6.5.2; mould showing myceliumP5 **For.6. 5.2; A mocha alternative to live

culture

24


Prepared micro slides P 2-3 For 11.5.4;Helianthus (sun flower) stem,(continued) of each transverse sections;

Lamium (dead nettle) stem, transversesections

P 2-3 **Hippuris vulgaris (mare's tail) stem,transverse sections

Protein-containing P 20 g For 7.21 and 11.7.22. LSmaterials of each Suggested materials are beans, fish,

hair, horn, lean meat

Rabbit T1 **Suggested organism for l':IJ.4.5 if available LS

Rat T1 **For dissection of alimentary canal for GGGH11.6.21 PH

Rhubarb, petiole P 2-3 For.l':IJ.6.12 - alternative: onion LSsticks

Sawdust Supply **Alternative to peat for mouse culture LS

Seaweed, e.g.Ascophyllum, P 5-10 g For 2.11 for iodine extraction. Collect LSFucus or Laminaria dried a large quantity and dry it

Serratia marcescens T 1 culture *For 64.10 - see Appendix 2 GGGHnon-pa thenogenic PHbacteria

Sugar, soft brown T 50-100 g For Drosophila culture medium LS

Tobacco, seeds T 1-2 For M.11, must contain albino mutant GHPHpackets

Turf Supply **For l':IJ. 8.20. Best to grow seed in trays LS

Water culture solutions Supply See Appendix 3 'Plant Culture Kit' GG

Wheat, seeds TlOg **For preparing culture solution for LSParamecium

Wholemeal flour T 500 g For Tribolium culture medium LS

Wood shavings Supply **Alternative to hay for mouse culture LS

Yeast, dried T1X For culture requirements and for yeast LS125 g culture - see Appendix 2(40z)tin

Zebrina (Tradescantia) Supply Suggested for 4.9 - see Appendix 2 LSsp 'Clones'

25

ChemicalsThe chemicals are listed according to their systematic names.However, since systematic nomenclature ds not yet fully used, someitems have been categorised according to semi-systematic or evencommon names. In all cases where other commonly used namesexist, these are included in the 'other names' column of the table.Where italics occur in this column they are systematic names.

To help in ordering chemicals, the source refers to the minimumquantities supplied. Most chemicals are available from all suppliers.When chemicals are generally supplied in the minimum quantitystated, no supplier codes are included in the 'source' column. Shouldonly a small quantity of a particular substance be required it mayprove cheaper and more convenient to purchase analytical qualityrather than general purpose reagents.

Hazards are coded in the 'hazard' column. Where the code letteris in upper case (capital), a reference will be found in Appendix 4.The codes used are

a or A = alergy hazard/ carcinogenicc or C = corrosivef or F fire riskg or G gas cylindero orO oxidising/reducing agentp orP poison

The absence of a code for any particular substance does notimply that there is no hazard associated with it, but that if handledproperly any hazard is minimal.

27

Name Formula Other names Hazard Quantityrequired

Acetone (CH3hCO Propanone; dimethyl f P 250 cm3ketone, DMK

P 200 cm-'

Albumen Egg albumen PSg

Aluminium A12(S04h· Alum, soda-alum T 20 gsodium sulphate Na2S04·24H20

Ammonium NH4CI Sal ammoniac TID gchloride

Ammonium NH40H Ammonia 0.880 s.g. C P T 1500hydroxide cm3

Ammonium (NH4hS04 P 12 gsulphate

Azolitmin Tlg

Baking powder Supply

Barium chloride BaC12·2H20 P T 122 g

Benedict's T 1000solution cm3

Bismuth Bi T 1-2pieces

Bromine Br CF T 1-2

Calcium carbonate CaC03 Marble chippings P 25 g

Calcium carbonate CaC03 T 10-20 g

Calcium chloride CaC12 T SOg

Calcium chloride CaC12·2H2O PSg

Calcium hydroxide Ca(OH)z Slaked lime T 100 g

Carbon dioxide CO2 G T 1 cylinder

28

Notes Minimum Sourcequantitysupplied

**For'" 8.7b - alternative to 500 cm-' GGMBtetrachloromethane PHFor electrode cleaning in 8.11

**Alternative to casein for'" 7.22 25 g GH

*Crystals for 68.14 SOD g

**Used as saturated solution for 250 g GH"'8.17

For 6.1b, 6.1 c and 7.21 2250 cm3 MB

*For 6A 8.20 used as 0.09 M 250 g GHsolution

For making litmus indicator 1 gsee Appendix 3

Household, in unlabelled LSjar for'" 1.3. Sodium hydrogencarbonate can be used asan alternative.

Used as 0.5 M solution for 8.19 250 g HWPHDispense one dropper bottle,use analytical quality

Buy ready made or make from 250 cm3 GHingredients, see Appendix 3

*For 68.14. Cast sticks, 100 g BDHalterna tive is cast zinc HW

For 6.1c. 1 cm3 capsules 12 cm-' HWPH

For .6.1.4 1 kg GGGH

**Powder for adjusting pH of 500 g GHculture solutions

Anhydrous for 6.26 250 g GH

For"'7.3 250 g GH

For lime water production 500 g GH

Ordinary cylinder, not siphon 1 cylinder BDHtype, for producing gas not solid BOC

29


Casein P5g

Charcoal C Carbon P 5-10 g

Cobalt (II) COC12 Cobaltous chloride T 1 bookchloride paper

Cobalt (II) CoS04.7H20 Cobaltous sulphate P 30 gsulphate

Copper Cu P 5 piecesP 5 piecesP 10 pieces

Copper (I) oxide CU20 Cuprous oxide; red T5gcopper oxide

Copper (II) CUC03 Cupric carbonate P 50 gcarbonate

Copper (II) CUC12·2H20 Cupric chloride P 5-10 gchloride P 20 g

Copper (II) CuCr04 Cupric chromate T 20-50 gchromate

Copper (II) oxide CuO Cupric oxide; black P 10-20 gcopper oxide

PlOD g

Copper(1I) CUS04 Cupric sulphate T 1-2 gsulphate

Copper (II) CuS04.5H20 Cupric sulphate; P 20 gsulphate hydrated copper (II) P 30 g

sulphate P 60 g

Cornflour Supply

Detergent e.g. Teepol Supply

Diethyl ether (CH3CH2hO Ethoxyethane, ether F T 100 cm-'

30


For·7.22 25 g BDH

=For 8.16b, granules for 500 gdecolourising

For 6.26 12 books BDWHW

For 1.1 and.0.6.11b 100 g GGMB

Foil Zf) mm X 20 mm for. 7.3 250 gFoil 20 mm X-10 mm for.8.7aFoil 80 mm X 30 mm for 8.11

For 2.4 250 g BDH

For 1.1 and .1.2 100 g

For .8.7a 25 g BDH**Used as 0.5 M solution (see

Appendix 3) for 2.6

Used as saturated solution with 100 g BDHadded urea for "8.9 - see GGAppendix 3

Analytical reagent for. 7.19 100 g BDHGGHW

General purpose reagent for 100 g GHMB2.4,.7.3 and 8.16

Anhydrous for water testing 250 gin 6.26 can be prepared fromhydrated salt

Used as 0.05 M solution in 8.11 250 g GHHW*Several uses as solid and solution MB

**Several uses including makingBenedict's solution

Household, in unlabelled jar for LS·1.3

Washing up liquid, several uses, LSTeepol is recommended

Mainly used for etherisers 500 cm3 HW

31


Ethanol CH3CH2OH Ethyl alcohol; meths; f P 100 cm-'methylated spirit; IMS

Fly spray p T I spray

Glycerol CH20H.CH Propan-I ,2,3-triol T 50 cm3

(OH).CH20H

Graphite C Carbon: colloidal T 1 jargraphite (Aquadag)

Household Supplymaterials

Hydrochloric HCl Spirits of salts C P 500 cm3

acid

Hydrogen H2 G T I cylinder

Hydrogen H202 0 P 50 cm3

peroxide

Icing sugar Supply

Iodine CP T 75 g

Iron (II) FeS04·7H20 Ferrous sulphate; PSgsulphate iron (II) sulphate

- 7 - water

Lead Pb P 5 pieces

Lead (II) acetate (CH3COOhPb Sugar of lead P P 38-190 g

Lead (II) PbBr2 P P 200 gbromide

Litmus indicator PI bookpaper of each

32type


For 8.11 and for diluting 2250 cm3 BDHethoxyethane in etherisers. GGIMS (industrial methylatedspirit) will suffice.

**Used for dealing with escaped 1 can LSDrosophila

Mainly for glycerol nutrient 250 cm3 GGHWagar - see Appendix 2'Agars and broths'

**For 8.5, coating spheres to give SOg GGPHa conducting surface

*For 68.15, examples could LSinclude foods, flavourings,washing substances and otherpowders and solids

The quantity includes all uses 2500 cm3

Mainly required for 5 Msolution

1 cylinder BDH

For 2.11, 20 vol. solution see 500 cm3 GGHW- Appendix 3

Household, in unlabelled jar LSforA.1.3

Mainly for preparation of iodine 25 g GHin potassium iodide solution -see Appendix 3

*For66.11b 500 g GGGHMB

Foil, 20 mm X 10 mm for 250 g GH"S.7aFor 7.7a 250 g ·GGGH

HW

Mainly for electrolysis in 100 gAS.1Oreclaimable

Red and blue papers for 7.21 12 books

33


Lycopodium AF P 10 g

Magnesium Mg F T5g

Magnesium oxide MgO Magnesia T5g

Mercury Hg Quicksilver P T 1-5 kg

Mercury (II) HgS04 Mercuric sulphate P T 100 gsulphate

Methyl cellulose e.g. Poly cell T 1 packet

Methylene blue PIg

Millon's reagent P P 100 cm3

Naphthalene C10HS f P 5-10 gNickel (II) NiC03 P 25 gcarbonate

Nickel (II) NiS04·6H20 PSgsulphate

Nipagin C6H4(OH). Methyl p-hydroxy- p T 5 gCOO.CH3 benzoate

Nitric acid HN03 CO P 350 cm3

Olive oil P 10 cm3

Paraffin wax candle wax T 1 kg

Perspex P 5-10 g

Petroleum oil Crude oil . f P 20 cm3

Petroleum spirit Petrol; octane; f P 250 cm3

gasoline; gas

Polystyrene P 10-20cm3

Potassium bromide KBr TlOg

Potassium chlorate KCI03 0 T 10 g

34


**For use with oil film kit for 25 g GGHW6.15 - alternative: talc PH

For 2.4 powder 100 g

For 2.4, light 500 g

**For work on pressure 100 g BDHGHHW

**For making Millon's reagent 25 g

**For slowing micro-organisms LS

For A.1.7b and 5.1 5g GHPH

For A7.22 100 cm-'

*For66.23 250 g GGFor 1.1 100 g GHHW

PH

*For ~.l1b 100 g GHMB

For Drosophila culture 100 g BDHmedium - see Appendix 2

Used mainly as 5 M solution - 500 cm3 BDHsee Appendix 3 HW

**For use with oil film kit 250 cm-' GGHWPHLS

For use with oil film kit and 500 gfor A8.7b

ForA8.7b, chips 250 g GG

ForA6.18 1000 cm3 PH

**For A8. 7b, alternative to xylene LS

Foamed (expanded) for AB.7b LSpackaging material

**Used as saturated solution 100 g GHfor A8.17

**Used as a saturated solution 250 g GHfor A8.17

35


Potassium KCl PSgchloride

Potassium K2Cr207 Potassium bichromate T 20 gdichromate T 10 g

Potassium 14Fe(CN)i5. Potassium ferro cyanide PSghexacyanoferrate 3H2O(II)

Potassium KOH Caustic potash C P 65 ghydroxide

Potassium iodide KI T 300 g

Potassium nitrate KN03 Salt-petre; nitre 0 T 20 g

Potassium KMn04 0 PIgpermanganate

Rocksil Supply

Sand P 25 g

Silica gel T500 g

Silver nitrate AgN03 c p P 100 g

Sodalime P 50-100 g

Sodium carbonate Na2C03 Washing soda T 100 g10H2O

Sodium chloride NaCI Common salt P 20 g

Sodium hydrogen NaHC03 Sodium bicarbonate T5gcarbonate Supply

Sodium hydrogen NaHS04. Sodium bisulphate T 10 gsulphate H2O

Sodium NaOH Caustic soda C P T 250 ghydroxide

36


For&7.3 250 g GH

*Crystals for68.14 100 g GH**Used as saturated solution

for &8.17

*For66.11 100 g GHMB

**Used as 1 M solution for &7.22 100 g GH- pellets, 90% or pure

For preparation of iodine in 25 g GHpotassium iodide solution

**Used as saturated solution for 250 g GH& 8.17

For&8.9 100 g GH

Used in place of asbestos or LSglass wool for&6.18

**For &7.10 LS

Used as desiccant for 2.4 and 250 g GH"in desiccator. Self indicating, HW6-20 mesh

Used mainly as 0.1 M solution 25 g

For 7.21, not self indicating 500 g

**For preparing Benedict's 500 g GHsolution

Various uses as solid and SODg GHin solution

*For66.13 500 g GH**Alternative to baking powder

for &1.3

**Used as saturated solution for 500 g& 8.17

Used as 5 M solution. Pellets, 100 g GH90% or pure

"}'7


Sodium nitrite NaN02 0 TSg

Sodium silicate Na2Si03 Water glass P 500 g

Sodium Na2S203- Sodium hyposulphite; T 20 gthiosulphate 5H2O hypo

Stains Supply

Starch P 10 g

Starch-iodide PI-2paper books

Strontium SrC12_ P5gchloride 6H2O

Sucrose C12H22011 Sugar (cane sugar) P 5-10 g

P 200 gT 300 g

Sugar Supply

Sulphur S f P 500 g

Sulphuric acid H2SO4 CO T 200 cm3

P 56 crn-'

Talc, powder French chalk P 10 gSupply

Tetrachloromethane CC14 Carbon P P 350 crn-'tetrachloride

Trichloromethane CHC13 Chloroform P T 5 crn'Trilead tetroxide Pb304 Triplumbic tetroxide: P 20 g

red lead oxide;dilead (II) lead (IV)oxide

38


**For preparing Millon's reagent 250 g GH

*Used as a 2 M solution for 500 g BDHL-6.11b - alternative: sodium PHmeta silicate

*Crystals for 68.14. Also used for 500 gsplashes of bromine and iodineon the skin

**Stains may be used foridentifying mice - seeAppendix 2 'Mice'

Used as 1% solution. Analytical 250 g BDHgrade, soluble HW

For 2.6 and A8.10 10 books MB

ForA7.3 100 g GHPH

ForA8.7a - free from 500 g BDHreducing sugars HWMB

*For 66.11e and ~6.12*For66.13

*Crystals of household varieties LSfor 68.14

Roll sulphur for 6.24 and A 7.4 500·g GH

**For Millon's reagent

For 2.5 M and 1 M solutions 1000 cm-' GHHW

For use with oil film kit 1 kg HWIn unlabelled jar for A 1.3

For 2.11, A6.10, 66.23 and 500 cm-' GGHWA8.7b PH

**For stabilising starch solution 100 cm3 GH

For &2.7 250 g GH

39


Trisodium citrate Na3C6Hs07· T 200 g2H2O

Turmeric paper P 1 book

Universal P 1 bookindicator paper

Urea NH2·CO.NH2 T 20 g

Vegetable black C Carbon T 20 g

Vinegar CH3COOH Acetic acid P 500 cm3

Wood splints P 1 pack

Xylene C6H4(CH3h f P P 400 cm3

Zinc Zn T 1-2specimensP 5 pieces

P 30 g

Zinc carbonate ZnC03 P 30 g

Zinc sulphate ZnS04·7H20 P 5-10 g

40


**For making Benedict's solution 500 g BDHGGHW

**For 7.21 12 books BDH

For 2.6, 6.24 and A-7.4 - pH 12 books BDHrange 1 - 14

For ..s.9 250 g BDH

For making blackened agar 250 g GGPHand blackened paraffin wax

ForA-1.3 - household LSGG

For 6.24 andA-S.7b, used as 500 cm3 BDHa solvent GGPH

**Cast zinc, alternative to 250 g HWbismuth for 6. 8.14 PHFoil strips 150 X 5 mm for 7.7a 250 g GHHWand 20 X10 mm for A8.7a PH

*Granulated, technical quality 250 g GHfor 8.166c

For 1.1 100 g GH

ForA8.7a 250 g GH

41

Geological specimens

SourceItem Quantity Notes

GGPHCalcite T 1-) **Large crystals for demonstratingcleavage

Rock set 1 P 2 sets For 2.3. Granite is also required for68.14. Contents of kit:1 basalt1 granitellimestone1 marble1 sandstone1 slate

RP

42

Teaching aids

Item SourceDescription

Chart

Duplication

Film

**Selection on diamonds, also booklets for 67.6 ID*Selection on industrial processes, examplesare: iron to steel, making a plastic,manufacture of an acid, Solvay process; for62.8Selection on iron and steel for 2.5Selection on teeth and dental care for"'6.21

**Outline map of Britain for 1.5Outline map of school grounds for 3.2

**Between the Tides for 3.2**Crystallisation for62.8**Distillation for62.8**Filtration for 62.8*Life in the Desert for 3.2Rocks that Originate Undergroundfor 2.3

Film loop, 8 mm **Alpha Particles for 67.18cassette type **Chlorine Manufacture NC f-14 for 2.6

**Chlorine Uses NC 1-15 for 2.6**Digestive Action in the Small Intestine

for ~.21**Dissection of a Rat; Alimentary Canal

for ~.21**Iodine Manufacture NC 1-17 for 2.11**Io.dine Uses NC 1-18 for 2.11

Iron Extraction NC 1-8 for 2.5**Laboratory Precautions for 64.10**Movement of Molecules NC 2-7 for 1.6

and 6.5**Pouring and Streaking for 64.10**Structure and A ction of the Stomach

for "'6.21**Sulphur Crystals NC 2-3 for 6.24**The Breeding of Roses for 64.13**The Results of the Selective Breeding

of Two Types of Hen for 64.13

Film loopprojector

This is an 8 mm cassette film loop projector. LSCare must be taken that Super-8loops are notshown on a Standard-S projector, andvice versa.

e.g.ICI MBINUnileverBSCCCHE

LSLS

BTICIICIICIRank

EB

MacmillanNCNCMacmillan

Gateway

NCNCNCNSSNC

NCNSSNSS

43

Item Description Source

Film projector A 16 mm projector is required LS

Jackdaw ** Volcanoes, Cape, for 2.3 LSpublications **The Discovery of the Galaxies, LS

Cape, for A7.3Jackdaws are available through mostbookshops. Several of each may beadvantageous

Mathematics aid **Rates and Gradients 1and 2 NMMSlide projector For showing 35 mm photographic LS

transparency slides and for experiment onobserving crystal growth

44

Books for Pupils and teachers

Background books for pupils, class sets requiredChemical formulae and equations IS, for.&.7.10 and 7.20

* * Chemicals from nature NC, 1966 for 2.3**Dalton and the atomic theory NC, 1966 for 7.23**Fertilizers and farm chemicals NC, 1966 for 6.&.8.20**Food preservation booklets from Batchelors and Smedley's

for 6 6.14**Growing crystals NC, 1966 for'" 8.17

Length and its measurement IS, for Section 2 onwards**Making diamonds NC, 1966 for 67.6**Materials LPT, 1966 for 2.11

The importance of patterns IS, for 1.5 and s Ll lPatterns of reproduction, development and growth IS,for "'3.7, 4.3, 4.9 and 5.1

**Project brief No. 10 SCPT, for 6.26Rocks and minerals IS, for 2.3

**The structure of substances NC, for.&.8.10**Varieties of cereals, Farmers Leaflet No.8 NIAB, for 64.13

Reference books suggested for class library. Several 0/ each arerequired

**Around the world Philip, London, 1969, for 2.1**Books and magazines such as Farmer and Stockbreeder and

nurserymens' catalogues, for 4.12**Guiness book of records, for6.&.4.2**Moore, P. Moon flight atlas Philip, London, 1969, for 2.1

Shell Let's collect rocks for 2.3Zim, H.S. and Shaffer, P.R.S. Rocks and minerals. Hamlyn1965, for 2.3

Books of dataAtlases or economic geography text books giving data on mineraldistribution, and world climate. For example, Oxford EconomicAtlas, for 1.5,2.9 and sLl

Three-figure tables for modern mathematics and science. Blackie &Chambers, for e Z.S and 7.16

Books for teachers**Bracegirdle, B. and Miles, P.H.An atlas of plant structure

vol. 1, Heinemann, 1971**Clarke et al. Biology by inquiry, book 1, Heinemann, 1972

45

Books for teachers continued

**Freeman, W.H. and Bracegirdle, B. An atlas of histologyHeinemann, 1967.

**Hallerton, T. (ed) Antarctica MethuenHandbook for teachers, ch. 10 NC

**Indices and molecules NMM**Kirkaldy, 1.F.Minerals and rocks in colour 2nd edn.

Blandford, 1968**NB Text and teachers guide III ch. 5 1966**NB Text and teachers guide IV eh. 2 1966

NC Sample scheme stage II, topic 11 1966NP Teachers guide III, Section 4 1966NP Teachers guide IV, Section 2 1966NSS Theme 2 1971NSS Theme 81971The importance of patterns. IS

**Planetaryastronomy, LPT 1 1969**Rowett, H.G.Q. Dissection guide III; The rat. Murray**Speed and Gradient. NMM**Starting geology. Shell**Stonehouse, B. Penguins. A. Barker, 1968

Teacher's handbook. IS**The artificial kidney. NAB Topic Review**The start of X-ray analysis. NC

The structure of substances. NC**Tolansky, S. Revolution in optics. Penguin

46

Preparation guide

IntroductionThe guide presents in tabulated form the requirements for the workof Sections 1--8 of the sample scheme. Short notes are includedwhere there seems a need and longer or more general points areexplained in the appendixes.

If information is given in the appendixes concerning individualpieces of equipment listed in the column headed 'Item', then afigure code is placed directly opposite the items, in the columnheaded 'App. ref.'( appendix reference). The figures used relatedirectly to the four appendixes.

Appendix IAppendix 2Appendix 3Appendix 4

Notes on apparatusNotes on biological materialsChemical preparationsHazards and precautions

The 'Reference' column lists all the pieces of work in the order inwhich they appear in the Teachers' guide and Pupils' manual;although, in many cases there is no equipment required.

The column marked 'Group', describes the nature of theworking group using a particular item of equipment. 'T' representsteacher (i.e. demonstration) requirements. 'P' represents pupilrequirements. This letter is usually followed by figures showing thenumber of pupils expected to be in a single work group. The letter'A' indicates that access is required by teacher or pupil to a limitednumber of items shared between all the groups working.

Asterisks occur in the 'Item' column to show optional pieces ofequipment.

Advance preparations are noted in the guide at appropriatetime intervals before the investigations to which they refer. Thetime has been estimated at seven periods (one fifth of the schoolweek) per week. The warnings will be incorrectly placed if more orless time is given to the course, or if a modified scheme is followed .

. These advance warnings are printed on half-tone strips across thecolumns of the table.

47

CalendarThis calendar is designed to aid technicians to prepare work forwhich materials are required in advance. Generally such materialsare biological.

It is assumed that the time allowance for the course is one fifthof the timetable (seven or eight periods) and that a term consists often full weeks.

Asterisks indicate optional organisms.

Week

Autumn term

1~ Section 2 'Galaxies, planets, and the Earth' (1~ weeks)

3 Section 3 'Communities and populations' (2 weeks)

4 Required specimens: Drosophila, *Paramecium, "Tribolium,*yeast for" 3 .7bTribolium castaneum and T. confusum for 3.8

5 Section 4 'Looking at organisms' (2~ weeks)Required specimens: Paramecium for 4.1Small mammals (as available) for 611.4.5

6 Required specimens: Drosophila and clones for 4.9Serratia marcescens for64.10

7 Required specimens: Barley or tobacco seedlings for •. 4.11*Mice for 64.13

48

Week7Yz Section 5 'Cells and more cells' (1 week)

Required specimens: Elodea for 5.1Amoeba for & 5.2

8Yz Section 6 'Molecules' (3Yz weeks)

10 Required specimens: Rhubarb or onion for ~ 6.12

11 Beginning of winter holiday

Spring termo Section 6 'Molecules' continued (1 remaining week)

2 Section 7 'Atoms and giant structures' (3YZ weeks)

5Yz Section 8 'The electron, ions and giant structures (3 weeks)

8 Required specimens; Lemna cultures for 8.19Turf for 6&8.20

8Yz _ Section 9 - The calendar is continued in Technicians'manual 2.

49

Section 1 Patterns and problemsTime required: 1Yz weeks

Reference Group Reqd Item App.no./q. ref.

1.1 P2 Dropper (teat) pipetteThe pattern of acids P2 **Hypodermic syringe, 2 cm3

and carbonates and needleP2 SpatulaP2 1 Stirring rodP2 1 Test tube, 125 mm X 16 mmP2 100 cm3 Hydrochloric acid, 5 M 3P2 1 bottle Lime water in dropper bottle 3P2 100 cm-' Nitric acid, 5 M 3P2 5g Cobalt (II) carbonateP2 5g Copper (II) carbonateP2 5g Nickel carbonateP2 5 g Zinc carbonate

.&.1.2 P2 1 Dropper (teat) pipetteMaking a prediction P2 1 **Hypodermic syringe, 2 cm3

and needleP2 SpatulaP2 1 Stirring rodP2 1 Test tube, 125 mm X 16 mmP2 1 bottle Lime water in dropper bottle 3P2 25 cm3 Sulphuric acid, 2.5 M 3P2 5g Copper (II) carbonate

50

Notes

Testing for the evolution of carbon dioxide maybe carried out by lowering a drop of lime wateron the end of a glass rod into the test tubeduring the reaction. Alternatively the drop maybe suspended from a dropper pipette or from ahypodermic syringe.The other method of carrying out this test is toextract the gas from the test tube using thedropper pipette or hypodermic syringe and thenbubbling it through lime water in a second testtube.

The pupils predict that sulphuric acid will releasecarbon dioxide from copper (II) carbonate, andthen test their prediction.

51


A1.3 P2 1 Dropper (teat) pipetteHunting the baking P2 1 Spatulapowder P2 1 Test tube, 125 mm X 16 mm

P2 100 cm3 VinegarP2A 4 jars Unlabelled jars containing

household materials

Al.4 P2 1 Dropper (teat) pipetteThe problem of P2 1 **Hypodermic syringe, 2 cm-',marble and needle

P2 1 Stirring rodP2 1 Test tube, 125 mm X 16 mmP2 25 cm3 Hydrochloric acid,S M 3P2 1 bottle Lime water in dropper bottle 3P2 25 cm3 Sulphuric acid, 2.5 M 3P2 5g Marble chips

1.5 PI **Duplicated outline map ofWeathering Britain

PI AtlasPI Patterns topic book, The

importance of patterns

1.6 P2A Two-dimensional kinetic modelMarbles as models kit:

40 marbles, approximately 16 mm1 shallow tray1 wooden partition to fit tray

T 1 **Film loop, Movement ofMolecules. N.C.

T **Film loop projector

52

Notes

Effervescence of the unknown solids withvinegar, an acid, is taken as indicating the presenceof a carbonate.

The jars should contain four different whitepowders which may need to be ground in a mortarwith a pestle in order to give them identicalappearances.

Suggested materials are: jar 1, cornflour;jar 2, french chalk (unscented talc);jar 3, icing sugar; jar 4, baking powder.

Baking powder will react with water because itcontains tartaric acid as well as sodium hydrogencarbonate. The baking powder used in thisexperiment could be sodium hydrogen carbonaterather than real baking powder.

The marble chips are shown to be a carbonate bythe action of hydrochloric acid on them. Whensulphuric acid is added, however, any reaction isshort lived owing to the formation of calciumsulphate on the surface of the chips.

53


AI.? P2 Hypodermic syringe, 10 cm3

Predicting pushes

c-DiscussionHydraulic brakes

6.1.8 P2A Selection Blocks of different materialsComparing solid and of differing sizesmaterials P2A 1 Balance, 1 place

PI 1-2 Graph papersheets

PI 1 Rule, 300 mm

1.9 P2 Forcemeter, 0-10 NPulling rubber PI 1 sheet Graph paper

P2 1 Metre ruleP2 1 Retort standP2 2 Bossheads and clampsP2 **Rubber band, 6-12 mm wideP2 550 mrn Rubber cord, 6 mm diameter

or square sectionP2A 1 ball String

.6.1.10 P2 Forcemeter, 0-10 N, or set ofPredicting pulls slotted masses on hanger

P2 Metre ruleP2 Retort stand, bosshead, clampP2 5 Rubber bands

.AI. 11 PI Patterns topic book - TIleProportionality importance of patternsagain

DiscussionPatterns and problems

54

Notes

No apparatus required.

Suggested materials are: aluminium, glass,iron and wood.Other materials can be used. At least 5different sized blocks of each material arerequired.The pupils plot mass against volume for eachmaterial and use their graphs to find the density.

The rubber band is a suggested alternative to therubber cord.It is suggested that the pupils might construct apush-pull forcemeter as a follow-up to thiswork. Details of a simple forcemeter are given inAppendix 1 'Push - pull forcemeter'.

The rubber bands should be of the same lengthand thickness.The arrangement of the apparatus by the pupilsforms part of the problem.

The topic book may be used at an early stage ofthe course.This investigation is not a piece of practical work.

No apparatus is required for this discussion of theimportance and uses of patterns.

55

Section 2 Galaxies, planets, and the EarthTime required: 172·weeks

Reference Group Reqdno./q.

Patterns topic book PI

2.1 PA SeveralEarth, a planet of life PA Several

"'2.2Planets in motion

Item App.ref.

Patterns topic book,Length and its measurement

**Books, Around the World**Books, Moon Fligli t Atlas

DiscussionThe Earth and its placein the Universe

2.3Looking at rocks

P4-6PI

1 of each1

PI 1

PA Several

PA Several

T

TT

11

Rock specimens**Background book, Chemicalsfrom Nature NCPatterns topic book, Rocksand mineralsBooks,Lets Collect Rocks.ShellBooks Zim and Shaffer.Rocks and Minerals HamlynFilm, Rocks that OriginateUnderground EBFilm projector**Jackdaw, VolcanoesCape

56

Notes

This book may be used at any stage during Part 1of the sample scheme.

A series of experiments is suggested in NSS Theme8, Field 2. The work described in this referenceincludes the use of a model of the solar system, theuse of photography in simulating the effects seenin astronomical photographs, evidence for themotion of the Earth using Foucault's pendulum,the use of polystyrene spheres in understandingthe phases of the moon, and the building and useof a simple astronomical telescope. Any practicalwork carried out here is considered so optional thatno further details are given in this Manual.

The specimens required are: basalt, granite,limestone, marble, sandstone and slate.

57


Item App.ref.

Advance preparation: Place the required reactants for Investigation 2.4in a desiccator now.

2.4 T 2 Beaker, 100 em 3

Getting copper T 1 Bunsen burner, matfrom its oxide T 1-2 Crucible,8 cm3

T 1 Filter funnel and paperT 1 Pipe-clay triangleT 1 Retort stand, bosshead, clampT 1 Safety screenT 1 SpatulaT 1 TripodT 50 cm3 Hydrochloric acid, 2 M 3T 2g Copper (I) oxideT 2g Magnesium powder 4T 2g Magnesium oxide

2.5Extracting iron fromiron ore

TTT

11Selection

Film loop Iron Extraction NCFilm loop projectorWallcharts on steel and iron

58

Notes

This demonstration is carried out in two parts. Inthe rust part a mixture of approximately 1 g eachof copper (I) oxide (red copper oxide) andmagnesium powder is heated in the crucible. Aviolent reaction occurs and the mixture tends tospew out of the crucible, which may crack in theviolence of the reaction. It is essential to placesafety screens between the apparatus and the classand between the apparatus and the teacher.

In the second part of the experiment an equivalentquantity of the reaction mixture is moderated bythe addition of up to 2 g of magnesium oxide. Thereaction is now much less violent and lumps ofcopper may be obtained by cleaning the crucibleand its contents in the beaker of hydrochloric acidand then filtering the acid. Before this secondreaction is carried out check that the crucible is notcracked and replace it if necessary.

The reaction can be carried out successfully usingcopper (II) oxide (black copper oxide) instead ofcopper (I) oxide. All substances used must be driedby placing in a desiccator a few days beforehand.If copper (I) oxide is to be used it must not beheated strongly to dry it because it differentiatesinto copper (II) oxide and copper metal. For noteson cleaning crucibles see Appendix 2 'Cleaningapparatus' .

59

Reference Group Reqd. Item App.no./q. ref.

2.6 P2A L.t. supply, 4-6 V d.c.Obtaining a useful gas P2 2 Connecting leads, 0.5 m fittedfrom salt with crocodile clips

P2 Electrolysis cellP2 1 Bunsen burner, matP2 1 Retort stand, bosshead, clampP2 30 cm3 **Copper (II) chloride, 0.5 M 3P2 30 cm3 **Copper (II) sulphate, 0.5 M 3P2 30 cm3 **Silver nitrate, 0.5 M 3P2 30 cm3 Sodium chloride, 0.5 M (or sea 3

water)P2A 1 book **Starch - iodide paperP2A 1 book Universal indicator paperP2 2-3 Wood splintsT 1 **Film loop Chlorine:

Manufacture. NCT 1 **Film loop Chlorine: Uses.NCT 1 **Film loop projector

.2.7 a P2A Asbestos paper, 50 mm X 30 mmLead from its oxide P2 Bunsen burner, mat

P2 1 pair TongsP2 1 g Charcoal powderP2 3g Trilead tetroxide (red lead oxide)

b P2A L.t. supply, 4-6 V d.c.P2 2 Connecting leads, 0:5 m fitted

with crocodile clipsP2 1 Electrolysis cell 1P2 2 Test tube, 100 mm X 16 mmP2 10 cm3 Hydrochloric acid,S M 3P2 3g Trilead tetroxide (red lead oxide)

60

Notes

rimless test tubes ------.75mmx10mm

test tube support

If the pupils have electrolysed sea water prior tostarting the Patterns sample scheme it issuggested that they should attempt one of theoptional salts listed.An accumulator will be adequate as the Lt. supplyrequired for this work.Notes on the construction and manipulation ofelectrolysis cells are given in Appendix 1.

clamp

connecting wire--- ....•

The pupils are asked to devise their own methodof extracting lead from its oxide. The apparatuslisted will be sufficient for two of the methodswhich they may choose (reduction with carbon orelectrolysis of the chloride). It is possible thatother methods which will entail other apparatusmay be suggested.Methods involving the use of magnesium powderor similarly active metals MUST be demonstratedby the teacher. See the notes to Investigation 2.4for details of this type of demonstration.

4-6Vd.c.

61

Reference Group Rcqd. Item App.no./q. ref.

.•.2.8 PI Selection Wallcharts and booklets dealing

The scale and economics with one industrial process

of some industrial T **Film selected from: Filtrationprocesses or Crystallization or

Distillation leIT **Film projector

2.9 PA Several Reference books and atlasesDistribution of giving data on the distributionminerals of minerals

2.10The effects on thecountryside of man'suse of materials

DiscussionThe diversity of livingthings

2.11 P2 1 g Dried seaweedIodine from seaweed P2 1 Beaker, 100 cm3

P2 1 Bunsen burner, matP2 1 Filter funnel and paperP2 1 Test tube, 150 mm X 25 mmP2 1 Tripod, gauzeP2 10 cm-' Hydrogen peroxide, 20 vol. 3P2 2cm3 Sulphuric acid, 1 M 3P2 3cm3 Tetrachloromethane (carbon 4

tetrachloride)

T Evaporating basin, 75 cm3

T Separating funnel, 100 cm-'T **Film loop, Iodine:

Manufacture NC.T Film loop, Iodine: Uses. NCT **Film loop projectorPI **Background book

Materials. LPT

62

Notes

Suggest processes for investigation are:iron ore to steel; making a plastic; manufacture ofan acid; Solvay process.

The pupils are invited to investigate world sourcesof copper, gold and uranium, and also to find outwhich minerals are available in Britain.



Laminaria, the ribbon seaweed, is recommendedfor this work but Fucus or Ascophyllum willalso work.The seaweed is boiled gently with about 10 cm3

of distilled water in the beaker for several minutes.The solution is filtered and the iodine is liberatedby addition of acidified hydrogen peroxide. Onshaking with tetrachloromethane, the iodine formsa purple solution in the organic solvent.There is insufficient iodine for pupils to separateout crystals from their own solutions so theteacher uses the funnel to separate off thetetrachloromethane layers produced by the class,and crystallises it at room temperature in a fumecupboard.A second method of extraction uses seaweed ash.It may be more convenient for inland schools toash a large quantity of dried seaweed and to usethe ash for this work. The ashing process shouldbe carried out in a fume cupboard since the smellcan be unpleasant. Heat the dried seaweed in airon a metal plate (e.g. a sand tray) or in a largeopen can (e.g. a 2500 cm3 paint tin). Stir the ashoccasionally during heating.

63

Section 3 Communities and populations

Time required: 2 weeksRequired organisms: For Investigation. 3.7 the Drosophila cultureswhich were set up at the end of the summer term and at one weekintervals are required; or the experiment may be set up in.A 3.7, inwhich case a stock culture of Drosophila will be required.Alternative organisms for Investigation. 3.7 are: Tribolium sp.,Paramecium caudatum or yeast. If Paramecium or yeast is used, itis likely that the experiment will be set up in .•.3.7 rather than inadvance of it.For Investigation 3.8 stock cultures of Tribolium castaneum andT. confusum are required. Each culture must be able to withstandwithdrawal of ten adults of each sex,


Item App.ref.

·3.1The Earth's greenmantle - A patternof distribution

PI 1 Book: Atlas

3.2Looking atcommunities

P2PI

T I

Compass (plotting)Duplicated outline map ofschool grounds**Film, Between the TidesBritish Transport**Film, Life in the DesertRank**Film projector

T

T I

3.3The schoolcommunity

DiscussionInequalities in humancommunities

64

Notes

The atlas should contain data on world-widepatterns of climate.

This is an exercise in sampling.No apparatus is required.

No apparatus is required.

65


3.4 PA Boiled, filtered pond water.Patterns of change PA Dried mud from the edge ofin a community a pond

PA Leaf mouldPA 3 Troughs, or plastic bowlsPA 1 Wax pencilPA Rain water or distilled water

a3.5Measuring thesize of populations b P2 4

P2P2A

21ball

c P2P2P2

122

P2P2T

12-6

Laths, 1 m long X 25 mm X10 mm wooden, marked at250,500 and 750 mm distancesStakes, wooden, or meat skewersString or garden twine

Beaker, 50 cm3

Dropper (teat) pipettesHand lens,X 8 or X 10,foldingMicroscope and lampMicroslides and coverglassesSquared paper for wall chartconstruction

6.&. 3.6

Measuring the size ofthe human population

66

Notes

Three troughs are prepared by covering the bottomwith dried mud and then adding a few handfuls ofleaf mould. The troughs are filled to two-thirdswith filtered pond water and the level of the wateris marked with the wax pencil. The troughs aresited out of doors in a place where they areunlikely to be tampered with, upset, overfilledby heavy rainfall or dried out by strong sun.

In order to decrease the extent of algal growthin the troughs they can be painted black, or blackpolythene washing-up bowls could be used. Fromtime to time it may be necessary to make up thevolume of water in the trough to the wax pencilmark. Distilled water or rain water should beused for this as chlorinated tap water is likely tokill any organisms in the troughs.

An alternative method for this experimentconsists of observations of a fenced-off area ofbare soil or lawn which is allowed to grow wild.

No apparatus is required for part a.

In b a lawn is divided into lanes one metre wideusing the stakes and string. The laths are used toconstruct quadrats one metre square.

An alternative method of sampling plants onopen grassland consists of throwing a metalquadrat square (made from heavy gauge galvanisedwire; sides approximately 250 mm) over one'sshoulder in an attempt to gain a random sample.

Part c will be carried out approximately onemonth later than parts a and b and the samplingwill occur at regular intervals over the next twoyears by one small group of pupils.


67


JJ. 3.7 PI **Patterns topic book PatternsThe growth of of reproduction, developmentpopulations and growth

a PI Large Small objects such as matchnumber sticks, beads, Tillich blocks,

Centicubes, etc.PI 1 sheet Graph paper

b PA The series of Drosophilacultures set up progressivelyfrom the end of the summerterm.

P4-6 1 Emergency etheriserP4-6 1 **EtheriserPI 1 sheet Filter paper, 100 mm squarePI 1 Hand lens, X 8 or X 10, foldingPI 1 Mounted needlePA 1 **Carbon dioxide cylinder, 4

fitted with rubber tube andsyringe needle

P2-6 1 bottle Ethoxyethane (diethyl ether) 4in dropper bottle

PA **Culture medium, stockculture of Drosophila,culture bottle and associatedapparatus required to set upexperiment b if it has notbeen prepared in advance

PA *The series of Triboliumcultures set up at the end ofthe summer term

P2 1 *Petri dish and lidP2 1 **PooterP2-4 1 *Sieve, 1 mm apertures (wire

mesh tea strainer or floursieve)

P2 1 *Soft hair brush

PA *Culture of Paramecium 2caudatum

68

Notes

The large number of small objects is used as amodel for population growth. The objects are to acertain extent optional.

For full details concerning the handling and cultureof Drosophila see Appendix 2.

Each of the cultures should have been set upin a one-third pint orange juice or milk bottle.Each of the bottles (containing food medium) isinitially established with five pairs of male andfemale flies, or with ten to twenty flies to ensurethe presence of both sexes. The bottles are keptin an incubator at 25°C and the flies transferredto identically sized bottles during the course ofthe culture so as to keep the cultures free ofdead flies. This transfer becomes especiallyimportant if fungal growths appe~r in the foodmedium.

Flies may be made unconscious by placingthe culture bottles on their side in a refrigeratorfor up to half an hour, or in the freezercompartment for a few minutes. Alternativemethods are etherisation or using carbon dioxide.If carbon dioxide is to be used, a slow stream ofthe gas is injected into the culture jar througha hypodermic syringe needle inserted through thestopper. The needle is connnected to the gascylinder with a length of rubber tubing.

Tribolium is used as alternative orin additionto Drosophila. Details concerning the culture andhandling of Tribolium are given in Appendix 2.

Paramecium can be used instead ofDrosophila. con tinued

69


.3.7 continued PA 100 cm3 *Infusion, hay in a conical 2flask 250 cm3

P2 1 *Dropper (teat) pipetteP2 1 **Microscope, binocular, or

hand lensP2 *Watch glass, solid

PA *Culture of yeast 2P2 1 *Dropper (teat) pipetteP2 1 *Microscope and lampP2 1 *Microslide and coverglassP2 1 bottle **Methylene blue in dropper 3

bottlec

.6d PI 1-2 Logarithmic - linear graphsheets paper (log-lin or semi

logarithmic)

e

3.8 T 50-100 Adult Tribolium castaneum 2Growing populations T 50-100 Adult Tribolium confusum 2together TA Food medium for Tribolium 2

T 1 Incubator set at 35°C andcontaining a dish of water

T 3 Jar, Kilner type, 500 g capacitywith fine muslin lid

T 1 Microscope, binocular, or handlens

T 1 Petri dish and lidT 2 **PootersT 3 Sieve, 1 mm apertures (wire

mesh tea strainers or flour sieves)T 1 Soft hair brush

70

Notes

Yeast may be used instead of Drosophila.

No apparatus is required for c.

t:, d is an exercise in representing data onlogarithmic graph paper rather than on theusual linear graph paper.

No apparatus is required for e.

The jars used in this experiment are filled to adepth of approximately 30 mm with food medium.Ten to twenty adult T. castaneum and ten totwenty adult T. confusum are put in one jar.This number should ensure approximately equalnumbers of each sex of each species. Sexing ofTribolium is difficult but could be carried outif so desired. Into the second jar are put 20-40adult T. castaneum; and 20-40 adultT. confusum are placed in the third jar. Jars 2and 3 are controls. Beetles are separated from thestock cultures by sieving them free of eggs andculture medium. When counting the controlpopulations a separate sieve must be used foreach container to prevent cross contaminationdue to eggs sticking to the mesh of the sieves.

The incubator should be checked morningand night and the dish of water kept topped upto maintain humidity.

Full details concerning the culture andhandling of Tribolium are to be found inAppendix 2.

71

Section 4 Looking at organisms

Time required:2% weeks

Required organisms:For Investigation 4.1 Paramecium caudatumis suggested as a live specimen rather than as a prepared microslide.For Investigation 6.IJJ. 4.5 a selection of small mammals is suggested.Organisms might include gerbils, hamsters, mice and rabbits "butthe choice will depend on their availability.

For Investigation 4.9 cultures of Drosophila showing typicallong-standing variations, such as vestigial wing and long wing, orwhite eye and normal eye, are suggested for examination. This is anoptional exercise.

For Investigation 4.9 clones of dandelions, Coleus or Zebrinaare suggested for examination. This is an optional exercise.For Investigation M.I0. A culture of Serratia marcescens isrequired.

For Investigation .&4.11. Tobacco or barley seedlings with albinomutants present are required.

For Investigationc 4.13. A breeding pair of unrelated mice isrequired to start a breeding experiment.


4.1 P2A Culture of Paramecium 2Measuring the cauda tumsize of small P2 Prepared microslide with smallorganisms organisms

P2 1 Dropper (teat) pipetteP2 1 Microscope and lampP2 1 Microslide and coverglassP2 1 Mounted needle or fine forcepsP2 1 Ruler, transparent plastic

with millimetre scale;

bo.& 4.2 TPA 1 **Book: Guinness Book ofInvestigating patterns Recordsin the size of organisms.

72

Notes

This investigation is essential for pupils who areunfamiliar with the use of a microscope, otherwiseit may be considered as an optional piece of work.

A suitable ruler is the oil film kit graticule.A transparent self adhesive scale (e.g. Scalafix)may be used instead of the transparent ruleror a piece of graph paper may be stuck to theside with self adhesive tape (e.g. Sellotape).

73


4.3 P2A Balance, 1 placeComparing measurements P2 32 Wooden cubes, l cm-'of linear dimensions, (Tillich blocks) or Centicubesmass and area as PI **Aid:Speed and Gradientorganisms grow 1 and 2 NMM

PI **Patterns topic book,Patterns of reproductiondevelopment and growth

6A4.4The influence ofshape

6A4.5 PA Small mammals as availableCan the pattern be P2A Balance, 1 placeextended to real P2A Newspaperorganisms? P2A Personal weighing machine

(bathroom scales calibrated inNewtons)

P2 Rule, 300 mm

A4.6 P2 1 Beaker, 1000 cm3

An investigation into P2 1 Bunsen burner, matkeeping warm and P2A 1 pack Cotton wool; non-absorbentcooling off P2 1 Flask, 100 cm3, round

P2 1 Flask, 500 cm-', roundPI 1 sheet Graph paperP2A 1 Measuring cylinder, 500 cm3

P2 2 Retort stands, bossheads, clampsP2 1 Stopwatch or stopc1ock or

watch with seconds handP2 2 Thermometers, -10 to +110oCP2 1 Tripod, gauzeP2 1 Wax pencil

74

Notes


Suggested mammals are: gerbils, hamsters, mice,rabbits, pupils and teachers.

The mass of the organisms and their surfacearea and approximate volume are estimatedand compared.

The pupils are asked to devise an experiment toinvestigate the effect of size on cooling. Theapparatus listed is the most likely to be selectedfor this work, but it is possible that pupils maywish to keep the size constant and experimentwith the effects of insulators such as fur orfeathers. Cotton wool may be stuck to flasks tosimulate fur, using a rubberised adhesive such asEvostick. If feathers are also used theymay be attached to flasks in the same way asthe fur but should be sterilised in an autoclavebefore use. Soft downy feathers are suitable andbest results are obtained if they are carefullystuck on in layers.The round part of the flask is unlikely to containthe nominal volume of water. An appropriatevolume of water is measured into each of theflasks used and this level is marked on the glasswith a wax pencil. In the most suitable flasks themark will be a short way up the neck. The flasksare emptied, supported by the retort standassemblies, refilled to the pencil mark with hot(70°C) water, and fitted with thermometerswhich are held in place with loose cotton wool plugs.

75

Reference Group Rejd Item App.no. q. ref.

4.7 PI 1 sheet Graph paperSearching for patterns PA 2 Metre rules or measuring tapeof variation

64.8 PI 1-2 sheets Graph paperA further look atvariation patterns,orHow to be honestlydishonest

4.9 PA *Cultures of Drosophila and 2Why are you like you clones of dandelions, Coleusyou are? and Zebrina

PI Patterns topic book, Patternsof reproduction, developmentand growth

64.10 P2A Culture of Serra tia 2Inheritance, environment marcescensand variation P2 Petri dish containing glycerol 2

nutrient agarP2 Petri dish containing nutrient 2

agar

P2 1 Bunsen burner, matP2 1 Inoculating loop 0 1P2A 1 Incubator set at 37 C

76

Notes

The metre rules may be mounted on a wall so thatpupils may measure their height.

Long-standing cultures of Drosophila arerequired. The cultures should be 'pure' andcontain flies with a readily observablecharacteristic such as vestigial wing or white eye.For full details concerning Drosophila seeAppendix 2.

The clones suggested will contain individualswith identical 'heredity'. Any variation in thesecircumstances is due to environmental factors.Several pots of each should be prepared. Oncethe clones are established the environmentalconditions of each pot from a set should bevaried, e.g. i kept very moist, ii kept almost dry,iii kept in bright light, iv kept well shaded. Thecompost mixture could also be varied. Fordetails of the suggested clone cultures seeAppendix 2, 'Clones'.

Suggested work for this investigation includesthe pupils gathering data about discontinuousvariations among their own relatives. Somereferences use the ability to taste phenylthiourea(PTU, also called phenylthiocarbamide, PTe)as an example of such variation, however, there isa health risk with this substance and it should notbe used.

In this investigation streak plates of Serratiamarcescens are made on two different types ofagar.

When incubated at 37°C the organism gives rise tored colonies on the glycerol nutrient agar and tothe normal white/translucent variety on nutrientagar.

continued

77


6. 4.10 continued T **Film loop, LaboratoryPrecau tions. NSS

T **Film loop, Pouring andStreaking. NSS

T 1 **Film loop projector

·4.11 P4-6 Supply Tobacco or barley seeds,The problem of mixture containing albinothe yellow plants mutants

P4-6 Petri dish containing blackened 2agar for tobacco seeds

P4-6 Plant pot, 100 mm diameterP4-6A Supply Seed compost for barley seeds

4.12 Selection **Books and magazines such asMaking use of Farmer and Stockbreederinherited variation and nurserymen's catalogues

6. 4.i3 TPA 1 pair Mice, unrelated breeding 2Breeding from pair e.g. 'Jan' strainselected organisms TPA Balance, e.g. top pan reading

to one or two placesTPA 5 Cages for miceTPA Supply Food for miceTPA Supply PeatTPA Supply Straw or wood shavingsT 1 **Film loop, The Breeding

of Roses. NSST **Film loop, The Results of the

Selective Breeding of Twovarieties of Hen. NSS

T **Film loop projectorPI **Leaflet, Varieties of

Cereals, Farmers Leaflet No.8

78

Notes

Tobacco seeds are sown on blackened agar andincubated in the dark at 20-2SoC. Theseedlings are transferred to the light after about aweek and will segregate into the albino and greenforms over the next few days. Light is requiredfor the formation of chlorophyll, the cause ofthe green colour. Albino seedlings will die offbecause they lack chlorophyll, when they haveused up the food resources of the seeds.

The procedure is almost identical for barleyseeds but these are grown on seed compost.

Perpetuation of stocks of seeds may be carriedout by allowing the seedlings to mature, and toself pollinate. The flowering heads are enclosedin bags to prevent accidental cross fertilization.This crop should be grown out of doors.

The experiment involves breeding the mice overa one-year period.

Selection of the mice is made by mass, sothat heavy and light strains are produced bythe end of the work.

Full details concerning the breeding ofmice are to be found in Appendix 2.

79

Section 5 Cells and more cells

Time required:1 weekRequired Organisms:For Investigation 5.1 Elodea (or other thin-leaved plants) and onion are required.For Investigation A 5.2 Amoeba is suggested as a live specimen ratherthan as a prepared microslide.


5.1 P2A Elodea or other thin-leavedInvestigating the plantstructure of P2A 2 bulbs Onion or other bulb 2organisms P2A Selection Prepared rnicroslides or

transparenciesP2 2 Dropper (teat) pipettesP2A 1 pack Filter paperP2 1 pair ForcepsP2 1 Microscope and lampP2 2-4 Microslides and coverglassesP2 1 Mounted needleP2 1-2 Tooth picks (wooden cocktail

sticks)P2A 1 bottle **Iodine in potassium iodide 3

(I2/KI) in dropper bottleP2A 1 bottle Methylene blue in dropper 3

bottleT 1 **Slide projectorPI 1 Patterns topic book,

Patterns of reproduction,development and growth

AS.2 P2A Culture of Amoeba 2The structure of P2 1 Prepared rnicroslide orAmoeba and a transparency of a mouldmould showing the mycelium

P2 1 Dropper (teat) pipetteP2A 1 pack Filter paperP2 1 pair ForcepsP2 1 Microscope and lampP2 1 Microslide and coverglassP2 1 Mounted needleT 1 **Slide projector

80

Notes

Suggested microslides (or photomicrotransparencies)are: cartilage; gut, transverse section; red blood cells

12/Kl is suggested as an alternative to methyleneblue.

If photographic transparencies are usedinstead of prepared micro slides only one ofeach will be needed.

The slide projector is required only iftransparencies are used.

A prepared micro slide (or transparency) ofA moeba is suggested as alternative to the liveorganism.


81

Reference Group Rejd Item App.no. q. ref.

5.3 PT Selection Photographic transparenciesStructure and PTA 1 Slide projectorfunction in cellsand tissues

.6.5.4 P2 2 Prepared microslides (orStructure and function transparencies) of the stemin an organ of a hind plant

P2 2 **Prepared microslides of thestem of an aquatic plant

P2 Microscope and lampT **Slide projectorT **Forcemeter, 0-10 NT 1 **G-clampT 1 **Glass rod, 200 mm X 5 mm

diameter approximatelyT **Glass tube, 200 mm X 5 mm

overall diameter approximatelyT **Retort stand, bosshead, clampT 1 pair **Safety gogglesT 1 **Safety screenT 1 **Swab or duster

82

Notes

The transparencies suggested are: cheek cells;nerve cell showing axon; sperm; tendon,longitudinal section; xylem tissue, longitudinaland transverse sections; leaf epidermis andcuticle, vertical section; bone, longitudinaland transverse sections.

Suggestions for the land plant are: Helianthus(sunflower), transverse section; Lamium (deadnettle), transverse section.

Suggestions for the aquatic plant are: Hippurisvulgaris (mare's tail), transverse section.


An optional demonstration involves breakinga glass rod and tube of equivalent size. Thearrangement of the apparatus is shown in thediagram. A safety screen should be placedbetween the apparatus and the class. A dusteror swab is wrapped around the glass to preventsplinters from flying off.

retort stand ------<11

t

forcemeter

glass tube orrod

G-clamp

'-------------swab wrappedaround glass

bench

83

Section 6 Molecules

Time required: 3~ weeksRequired organisms:For Investigation t::,.A 6.12 rhubarb or red skinnedonion is required for plasmolysis experiments.For Investigation A.6.21 a rat may be required for dissection of thealimentary canal. This is an optional but desirable requirement.

Reference Group Reqd Item App.no./q~ ref.

6.1 a P2 1 Bunsen burner, matExperiments with gases P2 2 Gas jars and covers or test

tubes, 150 mm X 25 mmP2A Supply Carbon dioxide 4P2 1 bottle Lime water in dropper bottle 3P2 Supply Town gasP2 1-2 Wood splints

b TA 1 pack Cotton wool, absorbentT 1 Glass tube, 1 m X 20 mm

diameter, with solid corks tofit

T 2 Retort stands, bossheads, clampsT 1 pair TongsT 20 cm3 Ammonia, s.g. 0.880 4T 20 cm3 Hydrochloric acid, concentrated 4

c T 1 Bromine diffusion kitTA 1 Fume cupboardT 1 pair PliersT 1 Retort stand, bosshead, clampT 1 pair Rubber glovesT 1 Translucent screen and 60 W

lampT 2500 cm3 Ammonia, 2 M in plastic 3

bucketT 500 cm3 Ammonia, ~-strength in 3

1000 cm3 beakerT Bromine capsule, 1 cm3 4

84

Notes

This is a traditional diffusion of gases experiment.Each gas jar is filled either with carbon dioxide ortown gas (or hydrogen) and the covers are put on.One gas jar is inverted over the other one and thecovers are slid out leaving the mouths of the twojars in contact. After some minutes each jar istested for the presence of carbon dioxide usinglime water, and for town gas by igniting thecontents with a wood splint.

The glass tube is supported horizontally usingthe retort stand assemblies. A wad of cotton woolsoaked in concentrated hydrochloric acid is placedin one end, and a similar wad soaked in theconcentrated ammonia is placed in the other end.The bungs are inserted and the apparatus isleft to stand for some time until a white ring ofammonium chloride is seen to form. Ammoniadiffuses faster than hydrogen chloride (from theacid) and so is inserted into the tube last. Thedemonstration is best carried out in front of adark background.

Full details concerning the use of thisequipment are to be found in Appendix 1Before assembling the apparatus check thatall rubber bungs and tubing are not hard orperished due to previous exposure to bromine.Replace them if necessary.The beaker of ~-strength ammonia is used toneutralise any accidental spillages of bromine

After the experiment open the tube under the2 M ammonia in the bucket. Wear rubber glovesfor the cleaning operation. If a fume cupboardr----'-~ __,is available it should be used while cleaning is L...- ---'

carried out.

10---- diffusion tube

stopcock

continued

thickrubber tube

bromine capsule

85


Item App.ref.

6.1 COil tinued

Discussion a T Watch glass, 50 mm diameterDiffusion of gases T 2 cm3 Ethoxyethane (ether) 4

b T 3-4 BalloonsT 1 * * Pump, vacuum/compression 1T 1 Carbon dioxide cylinder 4T 1 Hydrogen cylinder 4

6.2 P2A Two-dimensional kineticUsing the kinetic model kit:theory model 6 marbles, approximately 16 mm

1 marble, approximately 25 mm1 shallow tray

DiscussionThe kinetic theory

.6.3 P2 1 Chalk, soft blackboardGas diffusion P2 2 Glass tube, 100 mm X 8 mm

external diameterP2 Plastic tube, 100 mm X 8 mm

internal diameter, transparentP2 1 Retort stand, bosshead, clampP2A 1 Hydrogen cylinder 4P2 5 cm3 Soap solution 3

86

Notes

Ammonia is corrosive and must not be used onthe eyes - see Appendix 4.

Some bromine diffusion experiments use gas jarsas in a above. Due to the hazardous nature ofbromine it is inadvisable to use this technique.

The ether (or scent) soon vaporises and diffuses.The class is made aware of it by the smell.In the second experiment balloons are filled withdifferent gases. Air may be pumped directly into aballoon and town gas is led through the intakeof the vacuum/compression pump and the outletis attached to the balloon. Balloons may be filleddirectly from gas cylinders.


The apparatus is assembled as shown in thediagram.

glass PVC glass

diffusion tube assembled

The chalk may be filed to the correct diameter byplacing in the chuck of an electric drill supportedin a drill stand. Hold the flat file gently against the continued

87

Reference Group Reqd.no./q.

Item App.ref.

A6.3 continued

T 1 **Beaker, 250 cm3

T 1 **Beaker, 1000 cm3

T 1 **Porous pot fitted with singlehole bung and glass tube,200 mm long

T 1 **Retort stand2 **Bossheads and clamps

T 1 **Hydrogen cylinder 4

A6.4 P2A L.t. supply, 12 Va.c.Brownian motion P2 1 Whitley Bay smoke cell

P2 1 Bunsen burner, matP2 2 Connecting leads, 0.5 mP2A 1 pack CoverglassesP2A 1 pack Drinking straws, wax paper typeP2 1 Dropper (teat) pipetteP2 1 Microscope

88

Notes

chalk with the drill running at slow speed(300-1000 r.p.m.), The chalk should fit snuglyinto the plastic tubing.

Care must be taken when filling the tube withgas to prevent soap films breaking and runningdown onto the chalk, since this will cause failureof the experiment. Should the chalk become wetit must be replaced. It is advisable to have a supplyof spare sets of apparatus ready prepared.

The flow of gas from the gas cylinder shouldbe as slow as possible. The delivery of gas is easiestthrough a fine glass jet - see Appendix 1'Jets'.

For the optional demonstration the apparatus isarranged as shown in the diagram. Thisdemonstration is an alternative to the classexperiment described above.

Microscopes with fairly low power objectives(e.g. X 4) but large apertures are required. Theremust be sufficient clearance. between the stageand the objective to take the smoke cells. Afocal length for the objective of about 18 mm isideal and a X 10 eyepiece is used.

A suitable source of smoke is a lighteddrinking straw. The smoke is drawn through thestraw using the dropper pipette (see diagram) oris allowed to descend into the smoke celldirectly from the unlit end of the straw.

flame

t-----hvnroln"nin1000 cm3 beaker

~----glass tube

----water in250cm3 beaker

optionaldemonstrationapparatus

.~ jPiPette

.~

89


6.5 P2A Two-dimensional kinetic modelModel of Brownian kit:Motion 24 marbles, approximately 16 mm

2-3 marbles, approximately 25 mm1 match box, approximately

50 mm X 35 mm X 20 mmshallow tray

T **Film loop Movement ofMolecules NC


~6.6 P2A Two-dimensional kinetic model kit:Making a prediction 24 marbles, approximately 16 mm

shallow traywooden partition to fit tray

6.7Compressing a gas

TT

11

Boyle's law apparatusFoot pump and adaptor

90

Notes

91

Reference Group ReJd Item App.no. q . ref.

• 6.8 T 1 Three-dimensional kineticA three-dimensional model kitmodel

·6.9Warming the airinside a tin can

P2P2

P2

Bunsen burner, matCan with lever-top lid atleast 100 mm diameter (c.g,treacle tin)Tripod

Discussion T 1 **Barometer tubeAtmospheric pressure T 1 **Mercury tray

T 1 **Mercury troughT. 1 **Metre ruleT **Retort stand, bosshead,

clampT **Translucent screen and

60 WIampT 1-5 kg **Mercury 4

.6.10 T Test tube, 150 mm X 25 mmExperiment with a with solid bungcoloured crystal T 30 cm3 Tetrachloromethane (carbon 4

tetrachloride)T 2g Iodine crystals 4

66.11 a P2 1 Beaker, 100 cm3

Diffusion in liquids: P2 50 cm3 Copper (II) sulphate, 0.25 M 3Osmosis P2 0.5 g Potassium hexacyanoferratc (11),

one crystal the size of a pea

b P2 1 Beaker, 250 cm3

P2 130 cm3 Sodium silicate, 2 M 3P2A Selection Crystals

c T 1 Beaker, 250 cm3'T 1 Dropper (teat) pipette

92

Notes

This model consists of a transparent tube at thebottom of which is a vibrating diaphragm. Smallspheres are placed in the tube and when inmotion form a model of molecules moving in thetube. Various forms of the apparatus may bebought, anyone of which will be suitable forthis demonstration.

If the lid is not pressed on too hard sufficientpressure builds up inside the can when it isheated to force the lid off. If the lid is too tightthe can may leak at the joints and becomeunusable for repeat experiments.

A small quantity of water in the canproduces satisfactory results when heated.

This demonstration is the traditional work on thesimple mercury barometer. See Appendix 1'Cleaning apparatus' for notes on cleaningbarometer tubes.

Pour the tetra chloromethane carefully into thetest tube to avoid disturbing the crystal placed inthe bottom. This is easily accomplished by usinga dropping funnel for the solvent, which is addedslowly as the funnel is removed.After setting up the experiment should be leftundisturbed for 24 hours for the diffusion to becompleted.

Suggested crystals are: cobalt (II) SUlphate,copper (II) sulphate, iron (II) sulphate,nickel (II) sulphate.

The main problem with this experiment is inattaching the membrane to the thistle funnel so

continued

93


6.6.11 con tinued T Membrane, cellulose (jamjar cover)

T 1 Retort stand, bosshead, clampT 2 Rubber bandsT 1 Thistle funnel, 250 mm stemT 50 cm3 Sucrose, 50% 3

l\A.6.12 P2A 1-2 bulbs Onion (red-skinned variety) or 2Plant cells and rhubarb petiole (stick)solutions P2 1 Beaker, 100 cm3

P2 1 Dropper (teat) pipetteP2A 1 pack Filter paper cut to 50 mm X

20 mm stripsP2 1 pair Forceps, fineP2 1 Microscope and lampP2 2 Microslides and coverglassesP2 1 Soft hair brushP2 5 cm3 Sucrose, 50% 3P2A Tap water

94

Notes

that there are no leaks. The easiest method is tofit a rubber band to the funnel neck, attach themembrane, and hold it in place with a secondband which is fitted very tightly over it:- seethe diagram below. The first rubber band shouldbe 5-1 0 mm wide and be smaller in diameter thanthe neck of the funnel.

thistle funnel ----I

first rubber band

membrane

The funnel is inverted and can be filled to thestart of the stem by running the sucrose solutiondown t~e stem with a dropper pipette, or it canbe filled by plugging the end of the stem, inverting,filling and finally fitting the membrane.

The effects of immersing cells in strong sucrosesolution and water are investigated in thisexperiment.

95


6. 6.13 T 1 Balance, beam or torsion withUsing cell models beam

T 2 Beakers, 400 cm3

T 1 Bunsen burner, matT 4 Rubber bandsT 1 Test tube, 150 mm X 25 mmT 1 reel ThreadT 3 Visking tubing, 150 rnm long,

with one end sealed with a solidrubber bung (or thumb knot)and the other end with a bungcarrying a short capillary jet andscrew clip

T 1 bottle Benedict's solution in dropper 3bottle

T 5 cm3 Hydrochloric acid, 1 M 3T 30 cm3 Sucrose, 50% 3

96

Notes

r\·----screw cliporsmallstopcock

rubberbungSee Appendix 1 for making jets.

It is advisable to prepare a duplicate set ofapparatus before the lesson in case the Visking continued

97

Reference Group Reqd. Item App.no./q. ref.

c: 6.13 continued T 300 cm3 Sucrose, 75% 3T 5g Sodium hydrogen carbonate

c: 6.14 P2 30 g Batchelor's Surprise peasComparing preserved P2 30 g Dried peas (split peas)foods P2 30 g Fresh peas (if available)

P2 30 g Frozen peasP2 2-4 Beakers, 250 cm-'P2 1 Bunsen burner, matP2 1 Tripod, gauzePI 1 **Booklets - Food Preservation

Batchelors Ltd. and Smedley's Ltd.

6.15 P4A Oil film kit:How big are 1 beaker, 10 cm3

molecules? 4 mounted wire loops, holders,graticules

1 sponge1 sprinkler of Lycopodium 4

powder1 tray with wax surface, levelling

wedges, metal booms2 cm3 olive oil

P4 1 BucketPI 1 Hand lens, X 8 orX 10 foldingP4 1 Metre ruleP4A Detergent for washing up

l:::..A6.16 P2 1 strip HDPE (high densityBending polyethylene polyethylene)

P2 1 strip LDPE (low densitypolyethylene)

.A 6.17Some physical propertiesof alkanes

98

Notes

tubing develops a leak or is not securely sealed.The outside of the tubing should be washed cleanof any sucrose solution spilled during filling.The sucrose used should be free of reducing sugars.

In this experiment peas which have been preservedin different ways are cooked and compared againsteach other (and against fresh peas if available). Itis suggested that the home economics departmentmay help with this work.

Cans of processed and garden peas may also beincluded for comparison.

This experiment is optional for pupils who havepreviously carried it out.

Full details concerning the oil film kit and itsmanipulation are given in Appendix 1.

Check all trays and booms before the kit isissued, by running cold water over them. Wetpatches. on them after draining indicates tracesof detergent which will spoil the results.


99


A 6.18 P2 1 Beaker, 100 cm3

Separating molecules P2 1 Bunsen burner, matof different sizes P2 1 Dropper (teat) pipette

P2 1 Retort stand, bosshead, clampP2 4 Test tubes, 75 mm X 12 mmP2 1 Test tube, 125 mm X 16 mm

with side arm and fitted withbent 150 mm delivery tube andsingle holed cork.

P2 1 Thermometer, 0 to 360°CP2 1 Watch glass, 50 mm diameter,

hard glassP2 3 cm3 Crude oilP2A RocksilP2 1-2 Wood splints

6.19 P2 1 **Bunsen burner, matDialysis P2 1 Crystallising dish, 375 cm3,

100 mm minimum diameterP2 1 **Flame test wireP2 1 Graham dialyser and membraneP2A 1 bottle Iodine in potassium iodide

(l2/KI) in dropper bottle 3P2A 1 bottle Silver nitrate, 0.1 M, in 3

dropper bottleP2 50 cm3 Sodium chloride, 0.1 M 3P2 50 cm3 Starch,l% 3

100

Notes

In this experiment the pupils fractionate crude oiland investigate the properties of the fractions.

At the end of the experiment some test tubes maycontain tarry deposits. For methods of cleaningsoiled glassware see Appendix 1 'CleaningApparatus'.

heatt

Dialysers are expensive. The experiment can becarried out using Visking tubing in beakers.

101

Reference Group Reqd Item App.No./q. ref.

• 6.20 P2 Beaker, 400 em3 or waterHow does food get bathinto the body? P2 1 Bunsen burner, mat

P2 1 Dropper (teat) pipetteP2 1 Hypodermic syringe, 10 cm3,

disposableP2 3 Paper clipsP2 1 Rubber band for chewing onP2 1 Spotting tileP2 3 Test tubes, 75 mm X 12 mmP2 3 Test tubes, 125 mm X 16 mmP2 1 Test tube rackP2 1 Thermometer, -10 to -no'cP2A 1 reel ThreadP2 1 Tripod, gauzeP2 3 Visking tubing, 150 mm long,

14 mm diameterP2 Wax pencilP2 1 bottle Benedict's solution in dropper 3

bottleP2 1 bottle Iodine in potassium iodide 3

(Iz/KI) in dropper bottleP2 6 cm3 Sodium chloride, 0.1 M 3P2 30 cm3 Starch, 1%, analytical quality, 3

soluble

.6.21 T **Rat for dissection of 2The digestive system abdominal viscera

T 1 set **Dissecting instruments andboard

T 1 **Book: Rowett DissectionGuide III: The Rat. Murray

102

Notes

The Visking tubing is cut to length before opening.The tubing is easily opened by soaking in waterfor a few minutes and then rubbing it betweenthe thumb and forefinger.The Visking tubes are filled as follows:tube 1, starch solution only; tube 2, salivasolution only; tube 3, starch and saliva mixture.

thermometer-----o/

theat

The starch solution as used in this experimentconsists of 70 cm3 of 1% starch solution mixedwith 30 cm3 of 0.1M sodium chloride solution.After a meal the enzyme concentration in salivatends to be low so it is advisable to dilute thestarch solution with its own volume of water(i.e. to produce a 0.5% solution).

The rat may be dissected before the period ratherthan the dissection being carried out in front ofthe pupils.

continued

103


.&.6.21 continued T Selection Charts on teeth and dental care,CCHE

T **Film loop Digestive Actionin the Small Intestine.Macmillan

T **Film loop, Dissection of aRat A limentary Canal.Gateway

T **Film loop, Structure andA ction of the StomachMacmillan


6.22The artificial kidney

b. 6.23 P2 1 Dropper (teat) pipetteMolecular crystals: P2 1 Microscope and lampNaphthalene P2 2 Microslides and coverglasses

P2 1 SpatulaP2 2 Test tubes, 100 mm X 16 mmP2 10 cm3 Tetrachloromethane (carbon 4

tetrachloride)P2 1-2g Naphthalene

6.24 P2 1 Beaker, 250 cm3

Molecular crystals: P2 1 Bunsen burner, matSulphur P2A 1 pack Filter paper

P2 1 Flask, 100 cm3, conicalP2 2 Hand lens, xs or XI0 folding;

or microscope, lamp, microslide,coverglass

P2 1 Mortar and pestleP2 1 Paper clipP2 1 Test tube, 100 mm X 16 mm

and holderP2 1 pair TongsP2 1 Watch glass, 50 mm diameterP2 25 cm3 XyleneP2 50 g Sulphur, rollP2A 1 book Universal indicator paperT 1 Model of sulphur (S8) molecule 1T 1 **Film loop, Sulphur Crystals.

NCT **Film loop projector

104

Notes


The pupils attempt to dissolve naphthalene inwater and in tetrachloromethane. They then usethe solution obtained in tetrachloromethane towatch the formation of crystals of naphthaleneas the solvent evaporates from a micro slide.

In this work crystals of rhombic and monoclinicsulphur are produced.Rhombic sulphur is crystallised from solutionin xylene.

Monoclinic crystals form as molten SUlphurcools in a cone of filter paper. When a crust ofsulphur has formed on the paper, the cone isopened allowing excess liquid sulphur to dropinto the beaker.

Sulphur is heated in a test tube during thisinvestigation. To avoid the problem of cleaningthe soiled tubes it is well worth keeping a classset which is used only for this work.

105

Reference Group Reqd. Item App.no.jq. ref.

6.25 P2A L.t. supply, 4-6 V d.c.Breaking up water P2 2 Connecting leads, 0.5 m fitted

with crocodile clipsP2 1 Electrolysis cellP2 1 Bunsen burner, matP2 1 Dropper (teat) pipetteP2 1 Retort stand, bosshead, clampP2 1 Test tube, 100 mm X 16 mmP2 1 bottle Lime water in dropper bottle 3P2 30cm3 Sulphuric acid, 1 M 3P2 1-2 Wood splints

6.26 T Beaker, 250 crn-'Making water from T Bunsen burner, matits elements T Delivery tube, right angled,

bore 6-8 mmT 1 Filter pumpT 1 Jet, from Bunsen burnerT 2 Retort stands, bossheads, clampsT 2 Rubber connecting tubing,

0.3-0.5 mT 1 Safety screenT 1 Test tube, 100 X 16 mm,T 1 Test tube, 125 X 16 mm,

with side arm, fitted withsingle-holed bung

T Thermometer, -10 to +110oCT Thistle funnel, 300 mm stem

with two right angled bendsT U-tube filled with calcium chlorideT book Cobalt chloride paper or anhydrous 3

copper (II) sulphateT Hydrogen cylinder 4PI **Background book, Project

Brief No.1 o. SCPT

106

Notes

Hydrogen is identified by the 'pop' test.Oxygen may be shown to be present by therelighting of a glowing splint, but tends to behidden by carbon oxides produced by the reactionof the oxygen with the graphite electrodes. Limewater is used to test for the presence of carbondioxide.

Hydrogen is passed from a cylinder fitted witha non-return valve through a drying tube (U-tubefilled with calcium chloride) and is burnt underthe thistle funnel as shown in the diagram. It isimportant to ensure that the now or hydrogenpassing through the jet is free from air, beforelighting the hydrogen flame. Allow the gas toflow for one or two minutes through the wide-bore delivery tube before fitting the jet, let thegas flow for another minute, then light it.Adjust the height of the flame, turn on the filterpump and move the thistle funnel over the flame.When turning off the jet take care that the flamedoes not burn back. Turn the hydrogen [lamedown and blow it out before turning offthe hydrogen [low.

clamp

coldwaterin 250 ern? beaker

107

Section 7 Atoms and giant structuresTime required.Szi weeks


7.1 P2 1 Circuit board and connectorsSeeing patterns P2 1-2 Dry cells (U2) 1.5 Vindirectly P2 1 MES bulb, 1.5 V 0.25 A, and

holderP2A 1 set Diffraction gridsP2 1 Microscope and lamp

7.2Looking at electronmicrographs

·7.3 P2 1 Bunsen burner, matSpectroscopic P2 1 Evaporating basin, 75 cm3

evidence for the P2 1 Filter funnelatom P2A 1 pack Filter paper

P2 1 Flame test wireP2 1 Retort stand, bosshead, clampP2 1 SpatulaP2 1 Spectroscope, direct visionP2 1 Test tube, 100 mm X 16 mmP2 1 pair TongsP2 1 Tripod, gauzeP2 1 Watch glass, 50 mm diameterP2 5 cm3 Hydrochloric acid, concentrated 4P2 5 cm3 Hydrochloric acid, 5 M 3P2 5 cm3 Nitric acid, 5 M 3P2 5 cm3 Sulphuric acid, 2.5 M 3P2 0.25 g Chlorides of calcium,

of each potassium, sodium, strontiumP2 1 piece Copper foil, 20 mm X 20 mmP2 1.5 g Copper (II) oxideT 1 **Jackdaw, The Discovery of

the Galaxies. Cape

.7.4 P2 1 Beaker, 250 cm3

Another look at P2 1 Bunsen burner, matsulphur P2 1 Mortar and pestle

P2 1 Test tube, 100 mm X 16 mmP2 1 Test tube holderP2 25 g Sulphur, rollP2A 1 book Universal indicator paperP2 1-2 Wood splints

108

Notes

The microscope is used with a low power objectiveto verify the pattern on the diffraction grids.


After seeing that the chlorides of differentsubstances emit different spectral lines, groupsof pupils prepare copper (II) chloride, nitrate orsulphate and investigate the emission spectrum ofthe three copper salts.

Only one-third of the class will use anyone ofthe dilute acids.

Notes concerning the handling of direct visionspectroscopes are given in Appendix 1'Spectroscope' .

After examining the behaviour of sulphur as itstemperature is raised, the pupils ignite the vapourgiven off when the sulphur is boiling. Dampindicator paper is used to test the gas producedby the burning vapour by holding it above theflame. Finally the liquid sulphur is poured fromthe test tube into a beaker of cold water. Theplastic sulphur produced is kept for at least24 hours. continued

109


Item App.ref.

&7.4 call tinued

&7.5 P2 1 kit Diamond structure kitGiant structures P2 1 pair Compasses or dissecting needle

T 1 Model of diamond structureT 1 Model of graphite structure

b. 7.6 PI **Background book, MakingA study of charcoals Diamonds. NC

T Selection **Charts and booklets from theIndustrial Diamond InformationBureau

7.7 a P2 Flask, 100 cm-', conical, orCrystals of metals test tube, 150 mm X 25 mm

P2 40 cm-' Lead acetate, 0.1-0.5 M 3P2 150 mm Zinc foil,S mm wide

b P2 Flask, 100 cm-', conical ortest tube, 150 mm X 25 mm

P2 40 cm-' Silver nitrate, 0.1 M 3P2 150mm Copper wire, 22 s.w.g.P2A Polystyrene spheres, 25 mmT **Kit, Investigating the

Properties of A luminiumAlloys. AF

& 7.8 PI Book of DataComparing themelting points andboiling points ofmolecules andgiant structures

67.9The extraction ofsulphur

110

Notes

It is essential to have adequate ventilationduring this work because of the sulphur oxideswhich are produced when sulphur is burned.

The pupils construct a model of diamondstructure using the compasses or dissectingneedle to bore the polystyrene spheres. SeeAppendix 1 'Molecular models' forconstruction details.


III


&7.10 P2A **Asbestos paper, 50 mm X 30 mmGiant structures from P2 1 **Beaker, 100 cm3

different atoms P2 **Bunsen burner, matP2 1 pair **TongsP2 1 **Tripod, gauzeP2 5g **SandPI 1 Patterns topic book,

Chemical formulae andequations

7.11Calculating thenumber of atoms

7.12 P2A Mole kit: 1Weighing in 'units' 1 balance, lever

1 sphere, blue1 sphere, red10 spheres, white1 sphere, yellow

7.13 P2A Mole kit:Weighing bags of 1 bag empty, opaquespheres 1 bag, opaque, containing blue

spheres1 bag, opaque, containing red

spheres1 bag opaque, containing white

spheres1 bag, opaque, containing yellow

spheres1 balance, leverStock spheres, white

112

Notes

The pupils are asked to devise and carry outexperiments to classify sand and water asgiant structures or molecules.

The apparatus listed is the most likely tobe required by the pupils. Thermometers arenot included since it is likely that they wouldbe broken by pupils trying to measure thetemperature of sand.A thermocouple and internal light beamgalvanometer could be used in this experimentas a demonstration by the teacher.

No apparatus is required.Investigations 7.11 - 7.20 inclusive may be

left until Section 10 'Particle interactions',sample scheme, Patterns 2.

Each opaque bag should contain equal butunknown numbers of appropriately colouredspheres.

113


7.14 P2A Mole kit:Finding the number 1 bag, empty, opaqueof spheres 1 bag, opaque, containing spheres

balance, leverStock spheres, white

P2 1 Rule, 300 mm

7.15 P2A Mole kit:Weighing in grammes bags, opaque, as in 7.13

Spheres, as in 7.12

P2A Balance, e.g. top pan

7.16 P2A Mole kit:From spheres to atoms bag, empty, transparent

bag, transparent, containingcalciumbag, transparent, containingcarbon

1 bag, transparent, containingmagnesiumbag, transparent, containingsulphur

P2A Balance, e.g. top panPI 1 Book of Data

7.17Avogadro constant

67.18 T **Film loop, Alpha ParticlesCounting atoms and Macmillanmeasuring volumes T **Film loop projector

"7.19 P2 1 Asbestos paper, 50 mm X 30 mmPatterns of P2A 1 Balance, 3 or 4 place (eg top pan)combination of P2 1 Bunsen burner, matatoms P2 1 Retort stand, bosshead, clamp

P2 Rubber connecting tubing,0.3-0.5 m

P2 Test tube, 125 mm X 16 mm,combustion type fitted withsingle-holed bung and straightdelivery tube, 70 mm long

P2 2g Copper (II) oxide, analytical gradeP2A Town gas

114

Notes

Any of the opaque bags containing spheres willsuffice for this experiment:


burning excess gas

slightly sloPingtesttube 1

town gas or hydrogen

heat

continued

115


Item App.ref.

.•. 7.19 continued

7.20 PI Patterns topic book,Formulae of compounds Chemical formulae and

equations

7.21 P2 1 Bunsen burner, matTesting for Nitrogen P2A Fume cupboard

P2 1 SpatulaP2 1-2 Test tube, 100 mm X 16 mmP2 Test tube holderP2A 1 bottle Ammonium hydroxide, 5 M 3P2 1 g of each Common high-protein

substancesP2 1 book Litmus paper, red and blue

of eachP2 10-20 g SodalimeP2 1 book **Turmeric paper

.7.22 P2 1 Bunsen burner, matTesting for protein P2 1 Mortar and pestle

P2 1-2 Test tube, 100 mm X 16 mmP2 1 Test tube holderP2 1 bottle **Copper (II) sulphate, 0.04 M, 3

in dropper bottle.P2 1 bottle Millon's reagent in dropper 3

bottleP2 1 bottle **Potassium hydroxide, 1 M, 3

in dropper bottleP2A Water, distilled or de-ionised 3

116

Notes

The c0J'per (II) oxide may be dried in an oven setat 110 C and stored in a desiccator until required.

In the interests of safety rubber bungs shouldbe used rather than corks.

The use of asbestos paper between the testtube and the copper oxide should avoid copperstains on the glass. For removal of copper stainsand traces of rubber see Appendix 1 'Cleaningapparatus'.

If only natural gas or butane is availablethen hydrogen must be used as the reductant.For notes on the use of hydrogen see Appendix 4'Gas cylinders' and Investigation 6.26.

The reduced copper oxide must be allowedto cool with the gas passing over it to preventreoxidation.

Suggested high-protein materials are: beans,fish, hair, horn and meat (lean).

Proteins release ammonia when heated withsodalime. The damp indicator paper will indicatethe presence of the alkaline ammonia althoughits smell may not be noticed in the fumes given off.

If no fume cupboard is available then theexperiments should be carried out near an openwindow since the smell can be most unpleasant.

Turmeric paper turns brown in the presenceof ammonia.

The copper (II) sulphate and potassium hydroxidesolutions are used in the biuret test for proteins,which is alternative to the Millon's test.

Biuret test: Make the protein extract alkalinewith a few drops of potassium hydroxide solution.Add copper (II) sulphate solution drop by drop tothe protein solution. Shake after each drop is added.A violet colour confirms protein, but if thecopper (II) sulphate is added too quickly this maybe masked by the blue colour of the copper salt. con tinued

117

Reference Group Reqd Item. App.no./q. ref.

.7.22 continued P2 0.5 g Casein and! or albumenP2A 1 g of each Common high-protein substances

as in 7.21

7.23 PI **Background book,Atoms, molecules Dalton and the Atomicand giant structures: Theory. NCFor good or ill

118

Notes

119

Section 8 The electron, ions and giant structures

Time required:3 weeksRequired Organisms:For Investigation 8.19 Petri dishes containingLemna growing in distilled and pond water are required. The dishesshould have been set up one or two weeks prior to the start ofSection 8.For Investigation D.. 8 .20 grass seed is required for growth in seedboxes. Turf can be used for this experiment. Grass seed may besown in advance of this work.

Reference Item App.ref.

Group Reqdno./q.

Advance preparation: If grass seed is to be used for Investigation 6IJ;. 8.20it should be sown in seed trays now.

8.1Electrostatic forces

P2P2P2P2P2

12211

Bunsen burner, matCellulose acetate stripsPolythene strips or rodsRetort stand, bosshead, clampWire stirrup on nylonmonofilament suspensionWoollen (flannel) cloth150 mm X 150 mm minimumsize

8.2How many sortsof charge?

P2

P2AP2AP2AT

SelectionSelection1

Apparatus as in 8.1Cloths,Rods or strips**Electroscope

·8.3Making a prediction

Apparatus as in 8.1P2A

120

Notes

The main problem with electrostatic experimentsis dampness, therefore, items like cloths,electroscopes, rods, etc. should be kept as dryaspossible. It is useful to fit a 60 Wor 100 W lampin the bottom of the electrostatics storage cupboardand to turn on this lamp overnight before theequipment is used. It is also necessary to keep allequipment clean and dust free. A line of dust mayact as a direct short and ruin an experiment.Certain cloths may become charged and these canbe discharged by passing them quickly through aluminous Bunsen flame.

During the investigation the room needs to bewell ventilated, and flames kept low to keep thehumidity to a minimum. Investigation 8.1-.&8.3are best not done on damp days.

Suggested rods or strips are: brass, copper,ebonite, glass, polystyrene and PVC.

Suggested cloths, minimum size150 mm X 150 mm, are: cotton, nylon and silk.

The pupils answer the question, What happenswhen a woollen cloth, charged by rubbing on apolythene strip, is brought near a suspendedcellulose acetate strip?

121


DiscussionCharge transfer

68.4 T Van de Graaff generator 4The Van de Graaff and accessoriesmachine

8.5 T 3 Connecting leads, 0.5 m longMoving charge and T 2 Electrophorus discs, 150 mmcurrent diameter

T 1 Internal light beam galvanometerT 2 Retort stands

3 Bossheads, clampsT 1 Sphere, conducting on nylon

mono filament suspensionT Van de Graaff generator 4

Discussion T 2 **Connecting leads, 0.5 m longElectrons T 1 **E.h.t. power supply 5 kV 4

T 2 **Electrophorus discs, 150 mmdiameter

T 2 **Retort stands3 Bossheads, clamps

T **Sphere, conducting on nylonmonofilament suspension

122

Notes


Accessories might include the 'head of hair' ,conducting sphere on nylon suspension, and otheritems at the teacher's discretion.

The sphere conducts well if coated with colloidalgraphite (Aquadag). Aluminium paint is notusually effective.

123


"8.6 T E.h.t. power supply,S kV 4Charge carriers in T Candlea flame T 1 Compact light source

T 2 Electrophorus discs, 150 mmdiameter

T 2 Retort stands, bossheads, clampsT 1 Translucent screen

.• 8.7 a P2 1 Circuit board and connectorsCharge carriers in P2 1-2 Dry cells (U2) 1.5 Vsolids and solutions P2 Ammeter, 0-1 A d.c.

P2 1 Beaker, 100 cm3

P2 2 Connecting leads, 0.5 mfitted with crocodile clips

P2 2 Electrodes, graphiteP2 1 MES bulb, 1.5 V 0.25 A, and

holderP2 SpatulaP2 Switch, push typeP2A Water, distilled or de-ionised 3P2 1 piece Copper, lead, zinc foil,

of each 20 mmX 10 mmP2 1 g Copper (II) chloride, lead (II)

of each bromide, sodium chloride,starch (soluble), sucrose,zinc sulphate

b P2A Circuit board and connectors andother electrical equipment asused in part a

P2 50 cm3 Tetrachloromethane (carbon 4

124

Notes

The e.h.t. supply to the discs is shown in thediagram. The candle is placed midway betweenthe discs which should be 100-150 mm apart.The screen and light source should be at least2 m apart with the candle midway between them.Blackout will be required for best results.The shadow shows two streams of ions from theflame towards the discs. This is not normallydirectly visible.

1.5Vdrycell+

switch ammeter A 0 - 1 A

,----,-crocodileclips

The same circuit is used as in part a.Paraffin wax will dissolve slightly in xylene orpetrol. It is not excessively soluble and less than2 g of wax is likely to dissolve in this experiment.

continued

125


A. 8.7 continued tetrachloride) or propanone(acetone)

P2 SOcm3 Water, distilled or de-ionised 3P2 SOcm3 Xylene or petrolP2 2g Paraffin waxP2 1 g Perspex chipsP2 2 cm3 Polystyrene, foamed

c P2A Apparatus as in part aP2 1 Bunsen burner, matP2 1 Dropper (teat) pipetteP2 Test tube, 100 mm X 16 mmP2 1 bottle Lime water in dropper bottle 3P2 1 bottle Silver nitrate, 0.1 M, in 3

dropper bottleP2 1-2 Wood splints

8.8 T Dry cell (U2) 1.5 VA closer look at water T 1 Beaker, 100 cm'

T 3 Connecting leads, 0.3-0.5 mT 2 Crocodile clipsT 2 Electrodes, graphiteT Intemallight beam

galvanometerT SOcm-' Water, distilled or de-ionised 3T 5g Sodium chloride

DiscussionCharge carriers insolution

126

Notes

Perspex and polystyrene will dissolve intetra chloromethane.

In part c the products of electrolysis areexamined.

Chlorine can be indicated by passing a sampleof gas through silver nitrate solution.

Oxygen may be detectable (relighting aglowing splint) but it is more likely that anyoxygen evolved will react with the graphiteelectrode to give carbon dioxide which can betested with lime water.

1.5Vdrycell

+

switch A internal lightbeam galvanometer

L "---.--crocodile clips

. ----f'--=:J

graphite electrodes


127


A 8.9 T 1 L.t. supply, 20 V d.c.Conduction by T 2 Connecting leads, 0.5 m, fittedcoloured salts with crocodile clips

T 2 Electrodes, graphiteT 1 Pipette, 25 cm-'T 1 Retort stand, bosshead, clampT 1 W-tube or U-tubeT 30 cm3 Copper (II) chromate/urea 3

solutionT 30-50 cm3 Hydrochloric acid, 2 M 3

P2P2

11

L. t. supply, 24 V d.c.Connecting leads, 0.3-0.5 mfitted with crocodile clipsFilter paper cut to 30 mm X20 mm stripsMicroslidePotassium permanganate, smallcrystal

P2P2 2

P2A 1 pack

DiscussionIons and giantstructures

128

Notes

demonstration W-tube

f--h""I.".-hloricacid

L-.-,..""",,,. (ll)chromate

Hydrochloric acid is poured into the W-tube untilit is about a quarter filled. The copper (II)chromate solution is then added through the centrelimb until it forms a clear division between twolayers of acid.

The filter paper is dampened with tap waterand fitted to the microslide. A small crystal ofpotassium permanganate is placed in the centreof the paper and the ends of the paper aregripped to the slide with the crocodile clips.When the supply has been switched on for aboutten minutes the colour of the permanganate can beseen to have moved towards the anode.

filter paper

pupil experiment


129

Reference Group Reqd Item App.no./q . ref.

.• 8.10 P2A L.t. supply, 6 V d.c.Charge carriers in P2 1 Bunsen burner, matmolten salts P2 2 Connecting leads, 0.3-0.5 m,

fitted with crocodile clipsP2 2 Electrodes, graphite, 200 mmP2 1 Retort stand, bosshead, clampP2 1 Test tube, 150 mm X 25 mmP2 25-30 g Lead (II) bromide 4P2A 1 book Starch iodide paperPI 1 **Background book

The Structure of SubstancesNC

8.11 P2A L.t. supply, 6 V d.c,A more detailed look P2 1 Ammeter, 0-500 rnAat what happens at the P2A 1 Balance, 3 or 4 placeelectrodes (e.g. top pan)

P2 1 Beaker, 100 crn-'P2 4 Connecting leads, 0.3-0.5 mP2 2 Crocodile clipsP2 2 Electrodes, copper foil

80 mm X 30 mmP2 1 Rheostat, 10-15 nP2 30 cm3 Copper (II) sulphate, 0.05 M 3P2A EthanolP2A Propanone (acetone)P2A Water, distilled or de-ionised 3

130

Notes

Ensure that the room is well ventilated.Heating must be carried out gently with analmost flickering flame and if excessive fumes areproduced heating should be stopped completely.The passage of the electric current has a heatingeffect on the melt, so the electricity itself mayalso need to be switched off until no furtherfumes are evolved.

The tubes in this experiment should be storedcarefully after use so as not to waste the remaininglead (II) bromide, which is expensive.

Electrodes should be removed from the meltbefore it has cooled to a solid or they may be keptwith the tubes.

The electrodes are supported bybending the top 10 mm over thelip of the beaker.

0-1 A(0-0.5 A) A ammeter

The water, ethanol and propanoneare used for cleaning the ·electrodes.

I+--!-----nraphite electrode

---lead (II)bromide

1heat qentlv

rheostat10-15 Q

6Vd.c.

beaker---

---copper (II)sulphate

131


8.12An application ofelectrolysis

A8.13Size of ions

68.14 PI 1 Hand lens, X8 or XI0, foldingExamining P2 1 Microscope and lampcrystals P2 1-2 Microslides

P2A Selection Crystals

68.15 P2 2 Hand lens, X 8 or Xt 0 foldingLooking for crystals P2A A wide range of householdat home materials

8.16 6a P2 1 Beaker, 100 cm3

Making crystals P2 1 Bunsen burner, matP2 1 Evaporating basin, 75 em3

P2 1 Filter funnel and paperP2 1 SpatulaP2 1 Tripod, gauzeP2 50 cm-' Sulphuric acid, 1 M 3P2 15 g Copper (II) oxide

6b P2 1 Beaker, 100 cm3

P2 1 Bunsen burner, matP2 1 Evaporating basin, 75 cm3

P2 1 Filter funnel and paperP2 1 Measuring cylinder, 25 em3

P2 1 Stirring rodP2 1 Tripod, gauzeP2 30 cm3 Hydrochloric acid, 5 M 3P2 1 bottle Litmus indicator in dropper 3

bottleP2 30 em3 Sodium hydroxide, 5 M 3P2 I g Charcoal, granular

6C P2 Beaker, 100 cm-'P2 Bunsen burner, matP2 Evaporating basin, 75 em3

P2 Filter funnel and paperP2 Test tube, 100 mm X 16 mm

132

Notes


Suggested crystals are: castor sugar, Demerarasugar, granulated sugar, icing sugar, aluminiumsodium sulphate, copper (II) sulphate,potassium dichromate, sodium thiosulphate,specimen of granite with unweathered faces andspecimen of cast bismuth or cast zinc.Other specimens might include galvanized metal,old brass and other minerals as available.

A wide range of materials is suggested. These maybe powders and could include foods, flavouringsand washing substances.

It is suggested that the pupils are divided intogroups for this work, so that one-third of thepupils will carry out preparation a, one-third band one-third c.

In c the rate of the reaction is greatly acceleratedby the addition of a small quantity of copper (II)sulphate solution (one small crystal). If pure zincis used the addition of copper (II) sulphatebecomes essential. continued

133


8.16 continued P2 1 Tripod, gauzeP2 25 cm-' Sulphuric acid, 2.5 M 3P2 1-2 Wood splintsP2 6g Zinc, granulated

A8.17 T 1 Beaker, 400 cm3

Watching crystals T 3-4 Dropper (teat) pipettesgrow T 1-2 Photographic transparency

slides 35 mm X 35 mrn, glassT 1 Slide projector, 35 mmT 3-4 Test tubes, 100 mm X 16 mmTA Detergent, liquid, e.g. TccpolTA Selection Saturated salt solutionsPI 1 **Background book,

Growing Crystals NC

A 8.18 P2 30 Polystyrene spheres, 25 mmUsing polystyrene T 1 **Hammerspheres to understand T 2 **Razor blade, hard backedcrystal shape T **Calcite crystal

T Model of body centred cubiclattice

T Model of hexagonal close-packed lattice

T Model of simple cubic lattice

8.19 T 3-4 Petri dish or crystallising dishPlant growth containing Lemna growing

in distilled water; labelled A.T 3-4 Petri dish or crystallising dish

containing Lemna growingin pond water; labelled B

P2 Beaker, ioo cm3

P2 Bunsen burner, matP2 1 Hypodermic syringe, 2 cm 'P2 1 Tripod, gauzeP2 1 Watch glass, 75 mm diameterP2 1 bottle Barium chloride, 0.5 M, 3

in dropper bottleP2 1 bottle Hydrochloric acid, 5 M, 3

in dropper bottleP2 1 bottle Nitric acid, 5 M, in dropper 3

bottleP2 1 bottle Silver nitrate, 0.1 M, in 3

dropper bottleP2A 1 set **Water culture solutions 3

134

Notes

The salt solutions stay in place on the slide best ifthe slide is first smeared lightly with detergent.

Suggested salts are: ammonium chloride,copper (II) sulphate, potassium bromide, potassiumchlorate, potassium dichromate, potassium nitrate,sodium hydrogen sulphate.

The warm saturated solutions of the saltsrequired can be kept in test tubes standing in a beakerof hot water.

Three or four pairs of dishes need to have beenset up approximately 4 weeks previously. Eachdish should contain ten plants when set up andduring the course of the experiment any loss ofwater should be made up with pond water orwith distilled water as appropriate. The dishesmust be scrupulously clean for this experiment.Cover the dishes to prevent contamination bydust. Do not put cultures in direct sunlight.

The beaker is used as a water bath on top ofwhich a watch glass of solution can be evaporated.

The reagents are used to test the culture mediafor the presence of chloride and SUlphate ions.

The water culture solutions are used in anoptional extension to this work in which theeffects of ion deficiencies on the growth ofLemna are investigated.

135

Reference Group Reqd Item App.no./q. ref

.<0.£.8.20 P2A 2 Seed trays containing grassUsing fertiliser P2A Ammonium sulphate, 0.09 M 3

PI **Background book, Fertilizersand Farm Chemicals NC

8.21Fluoride ionsand dental health

136

Notes

At least 2 seed trays should be set up for thisexperiment. Either equal masses of grass seedshould be sown in each tray about three weeksbefore the investigation or equivalent sizedpieces of turf should be placed in each.

One of the trays is watered with distilledwater and the other has ammonium sulphateadministered as part of its water intake.The rate of addition of the ammonium sulphatesolution is 500 cm3 m-2 monthly. Best results arelikely if grass seed is used and sown in sand whichhas been leached in the rain.


137

Appendix I Notes on apparatus

In addition to notes concerning the construction and use ofapparatus, this appendix includes information about individualitems and kits used in the Patterns scheme. It is not intended thatthe appendix should be a training manual for laboratory technicians,but it does include some elementary techniques which may berequired by them.

Bromine diffusion experimentThis is experiment 6.l c.The following notes refer to Nuffield Physics item 8, 'Bromine

diffusion kit' .

Contents of the kit6 Bungs, to fit stopcock and diffusion tube1 Brush, for cleaning stopcock2 Diffusion tubes, approximately 450 mm X 50 mm, with 25 mm

entry tube12 Rubber tubing lengths to connect test tube to stopcock2 Stopcocks,8 mm bore (Interkey) with bungs fitted6 Test tubes, rimless, hard glass (e.g. Pyrex)

12 Bromine capsules, 1 ern> (NP item 8A)Paraffin grease (Vaseline), small tin for lubricating stopcocks

Other apparatus requiredBeaker, 1000 cm> , containing 500 cm-' ~-strength ammoniumhydroxide - see Appendix 3Bucket, containing 2500 cm ' 2 M ammonium hydroxide -see Appendix 3

1 pair Pliers for crushing bromine capsules1 pair Rubber gloves1 Translucent screen and 60 W lamp

One kit and associated apparatus is required per school.

138

Warning

Bromine is a dangerous substance - see Appendix 4.If liquid bromine splashes onto the skin it causes severe blisters.

Bromine vapour will also attack the skin and will cause a sore throatif used carelessly. In general, bromine attacks skin, finger nails,metals, plastics, rubber and most other substances except glass andparaffin wax. Great care must be taken with bromine diffusionexperiments.

Bromine is obtained in small sealed capsules (ampoules) made ofglass, which are broken inside the apparatus to release bromine. Thecapsules should be handled carefully since the glass is very thin.

Safety precautionsBefore and during the experiment a beaker of quarter strength

(3.7 M) ammonium hydroxide should be at hand. Ammoniacombines with bromine to form harmless ammonium bromide.

If bromine splashes onto the bench or skin pour ammonia onto itat once. Ammonia must not be used near eyes. Wash affected eyeswith plenty of cold water and obtain medical attention - seeAppendix 4.

The apparatusThe main diffusion tube is a hard glass tube tube approximately

450 mm long by 50 mm diameter, with only one opening to a sidetube. A rubber bung fits into the side tube and carries the glass tubeof the stopcock. This glass tube from the stopcock extends throughthe bung and ensures that only bromine vapour comes into contactwith it. Bromine attacks rubber, and to have liquid bromine incontactwith the bung could lead to a hazardous situation. The bung shouldbe replaced with a new one as soon as bromine has hardened its face.The same bung can be used for several experiments but if it is keptfor a week or two after use the rubber will harden and may crack. Anew bung must then be used. The glass tube that continues out fromthe stopcock carries a short piece of thick walled rubber tubing whichmust be flexible and wide enough to admit the capsule or its snout.The other end of the rubber tubing is attached to a hard glassrimless test tube which is used to hold the bromine capsule until theexperiment is performed.

The stopcock should be of good quality, such as Interkey, withbore at least 8 mm. It is not necessary to use a special high vacuumquality stopcock but its tap must be spring held for safety.

139

The rubber tubing must be sufficiently flexible for it to besqueezed with pliers so as to crush the bromine capsule, which slidesinto it from the test tube, and it must be long enough not to pull offthe glass connections when squeezed.

With this arrangement, the breaking of the capsule to releasebromine is carried out separately, before the stopcock is opened toadmit bromine into the main tube. This enables the experimenter toconcentrate on the crushing of the capsule first and then to pay fullattention to the main experiment.

\o----diffusion tube

ithickrubber tube

stopcock test tube

bromine capsule

rubber bung

Procedure1. Check all rubber bungs and connections, before assembling theapparatus, by squeezing them. If a cracking noise is heard or ifcracks are seen the items must be replaced.2. Clamp the diffusion tube in a vertical position using a retort stand,two bossheads and two clamps.3. Set up the translucent screen and 60 W lamp behind the diffusiontube so that the tube is silhouetted against a bright background.

4. Fit the stopcock to the diffusion tube and make sure that it is inthe closed position.S. Fit the rubber tubing to the stopcock.6. Put the bromine capsule in the test tube and attach this to therubber tubing.

140

7. Tilt the test tube and tap it so that the capsule slides into therubber tubing. Crush the capsule with the pliers to release thebromine.

8. Open the stopcock to allow the bromine to enter the diffusiontube.

Cleaning the apparatusAfter the experiment the whole apparatus is put into a bucket,

half filled with 2 M ammonia solution - see Appendix 3. Theapparatus is taken to pieces under the solution in the bucket.

The lower end of the apparatus is plunged in first. The bung isremoved from the diffusion tube and the stopcock and other itemsare separated. The apparatus can later be washed, dried andreassembled. Paraffin grease (e.g. Vaseline) should be used tolubricate the stopcock, Do not use tap grease. .

It is sensible to wear rubber gloves for this cleaning process.Rubber gloves are not necessary during the main experiment as thiswould only invest the experiment with an air of danger which itdoes not deserve if carried out as suggested.

BungsA problem in using rubber bungs is boring them and then putting

glass tubing, glass rods, thermometers and electrodes through theholes.

If a cork borer is used for making the holes a lubricant such aswater, Teepol, glycerol or talc should be applied, and the bung shouldbe placed on a wooden surface to avoid injury and damage tobenches. The borer should be one size larger than the hole required.A dormer bit of the required diameter will drill through the bungquite successfully if used carefully.

When electrodes, tubes, etc. are inserted through a bung, a corkborer which is just large enough to slide over the item to be inserted,is lubricated with water or glycerol or talc and is pushed through thehole in the bung. The item to be inserted is pushed through theborer which is screwed out, leaving the item in place.

Removal of items from bungs, and adjustments to items in bungsis carried out by inserting a cork borer along the item beforeattempting to move it.

Cleaning apparatusBarometer tubes

Barometer tubes are easily cleaned by using 5 M nitric acid - see

141

Appendix 3 - for the first wash to remove traces of mercury. Afteremptying the acid, wash the tube successively with tap water,distilled water, ethanol or propanone (acetone), and ether (in thecase of ethanol) or more propanone. Dry by clamping the tube openend downwards by an open window or in a fume cupboard.

In the case of narrow-bore tubes (4 mm diameter) the cleaningsolutions may be applied via a glass hypodermic syringe fitted with aneedle. The tube is held at an angle as the cleaning liquids are runinto it. These narrow-bore tubes often give trouble when beingemptied. They may be supported at an oblique angle, open enddown, with a piece of swab against the open end to act as a wick.Stubborn mercury stains may be removed with 60% nitric acid - seeAppendix 3.

Copper stainsAny copper remaining firmly fixed to glass after reduction of

copper oxides will dissolve readily in a little 60% nitric acid - seeAppendix 3. Brown fumes of dinitrogen tetroxide N204 (nitrogendioxide N02) may be produced if a quantity of copper is present,so this cleaning operation is best carried out in a fume cupboard.

Magnesium residuesWhen heated in a crucible, magnesium will react with the

porcelain producing black stains which cannot be completelycleaned off. If the crucible is lined with asbestos paper the degreeof blackening will be reduced.

Crucibles which have been blackened by the reaction withmagnesium should be soaked in 5 M hydrochloric acid - see Appendix3 - which removes magnesium silicide, oxide, carbide, and nitride,but does not remove the black stains of silicon. During the cleaningprocess silanes produced from magnesium silicide ignitespontaneously on contact with air giving out flashes of light anda crackling sound.

Check that crucibles used with magnesium have not becomecracked and throwaway those which cannot be salvaged as brokenporcelain.

Rubber and organic materialBungs generally give a better seal to glassware than do corks and

are recommended for use, particularly when hydrogen or town gas ispassing through apparatus. When used with combustion test tubesthe bung may melt slightly leaving traces of rubber on the glass.

142

These traces may be removed from the glass by the use of scouringpowder or a suitable solvent such as propanone (acetone).

Hard carbon deposits in apparatus can usually be removed withscouring powder or steel wool.

Tarry deposits which are not removed by washing methodsmay respond to the use of organic solvents such as propanone(acetone) or cyclohexane. Soaking in proprietary cleaners suchas RBS 25 is effective for removing most organic substances.

Compact light sourceThis is Nuffield Physics item 21. It is required for Investigation

~8.6This is a 12 V 100 W tungsten halide (or quartz halide) lamp.

Note that when operating the lamp will draw a current of just over8A.

The lamp housing is designed so that when correctly positionedthe lamp filament can be seen sideways on through one opening andend on through the other. The lamp housing tends to become veryhot when in use and the connecting leads should not, therefore, besoldered on but be securely held by connecting terminals. Allow thelamp to cool down before moving it after use.

It is essential not to touch the quartz envelope as any grease on itwill appreciably cut down the light output and will shorten the lifeof the lamp. The envelope may be cleaned with ethanol (IMS) butgreat care must be taken not to jar the lamp, nor to add more greaseby touching it. If cleaning is not carried out carefully the effect maybe to spread grease already present rather than to remove it.

Electrolysis cells

There are two main criticisms of the commercially producedapparatus: the electrodes are thin and erode rapidly, and the glasssleeve tends to crack at the bung. The following construction methodsof which there are many variants, overcome these problems and canalso lead to a larger cell which can be used for volumetricdetermination of gas volumes if test tubes are replaced by graduatedtest tubes. Gas burettes can also be used for this purpose and havethe advantage of easy filling by drawing up the electrolyte with a20 em" plastic hypodermic syringe connected to the gas burette tapby a piece of plastic tubing.

Construction methodsIn both cells described gas collection is made in rimless 75 mm X

10 mm test tubes which may be filled with electrolyte and then

143

inverted over the electrodes without the electrolyte running out, andwithout the necessity for covering the open end. Test tubes withrims are very likely to spill out when inversion takes place. It is aswell to check the test tubes before issue to the pupils. The retainingability of the test tubes is enhanced by grinding their mouths planeon an oil stone and then lightly flame polishing the ground edge.

Method 1

polypropylenebeaker with holesbored in basewith a hot cork borer

II-----r--nraph ite electrodesmounted in rubber bungs

The beaker (or similar vessel) needs to have a fairly thick base.Method 2 This method makes use of a sleeve similar to the one produced

commercially but the diameter of the sleeve can be chosen to fitspecial requirements.

sleeve

rubber bung carryingtwo graphite electrodes

If glass tubing is used it is cut to length using the hot wire glasscutting technique - see Appendix 1 - and both ends of the cutsleeve must be carefully flame smoothed. Old fluorescent strip

144

lights are not suitable since the glass is too thin and fragile.The same principle of construction can be applied using plastic

tubes of suitable diameter and which are easily cut using a hacksaw.Perspex tubing is expensive but has all the advantages of the glasstype apparatus. Plastic water piping is relatively cheap but has thedisadvantage of being opaque.

Both methods use graphite electrodes which are bought in200 mm lengths. One electrode may be cut in half and will providethe two electrodes required per cell. For insertion of electrodesthrough bungs see Appendix 1 'Bungs'.

Test tube supports are easily made from 3.25 mm (1/s inch)marine plywood. Cut two strips of requisite length about 7-10 mmwide, so that the ends will overlap the edges of the electrolysis cell.Separate the strips with a hard wood spacer block. Use a round fileto make locating grooves on the inside faces of the strips. The testtubes are supported by the springiness of the plywood.

~-----------~~----------~or------------~~~--------~test tu be support

If the tubes are required close together replace one centralspacer with one at each end.

Electrical connections are made to the electrolysis cells bymeans of crocodile clips and stranded PVC coated wire.

Flame test wires and inoculating loops

Flame test wires are mounted lengths (25 mm) of, ideally,platinum wire about 26 s.w.g. - see Appendix 1 'Standard wiregauge'. Nichrome wire of similar thickness makes a good substitutefor platinum wire and is much cheaper. If a loop is made in the end ofa flame test wire by using a 5 mm rod as a former, an inoculatingloop is prod uced.1. Mount the wire in a needle holder. This method is the mostexpensive but has the advantage of easy renewal of wires and thereis no problem of cracking glass if the holder is accidentally heated.

2. Cut hard glass (e.g. Pyrex) rod to 100 mm lengths. Flame smoothone end and heat the other end strongly until very soft. Push thewire into the soft glass, remove from the flame, and allow to cool.

145

Note that glass remains hot for some time, so leave for ten minutesbefore handling.

nichrome (or platinum) wire ('-----------

glass rod

3. This method gives a much stronger joint than method 2. Fuse asoda glass melting point tube onto the end of the wire. Insert thetreated end of the wire into a length of glass tubing chosen to givea tight fit. Finally heat and fuse the glass together at the point ofcontact.

~==================~====wire very thin glass tube glass tube

146

4. Drill a piece of dowel as shown in the diagram and thread thewire through the holes. Make fast by circling the dowel and insertone end of the wire into the transverse hole.

[:~:~----------Hot wire glass cutting technique

Wide-bore glass tubing may be cut as follows:Wrap a length of 24-26 s.w.g. - see Appendix 1 'Standard

wire gauge' - nichrome wire round the tubing at the point of cuttingand hold it tightly in place while a current of 13-15 A is passedthrough for the required time. Make sure that there is a small gap sothat the ends of the loop of wire are not touching. The time will beapproximately 15-30 seconds depending on the type and thicknessof the glass used. In stubborn cases a splash of cold water round theplace at which the wire had been applied should effect a break.

Hard glass tubing is not easily cut by this method.

Internal light beam galvanometer

These instruments usually contain a moving coil and, instead of apointer, the movement of the coil is shown by a reflected spot oflight on a scale.

In order to increase the sensitivity of the meter the suspension ofthe coil is usually a thin strip of phosphor bronze to which themirror is attached. Such meters are extremely sensitive to smallchanges of current and are susceptible to mechanical shocks. Alwayshandle these instruments very carefully and before moving themensure that they are switched to shorted (or direct) on the rangecontrol knob. The current induced when the coil moves, stronglydamps the motion of the coil when the meter is switched in thisway.

JetsTwo jets can be made from a 250 mm length of glass tubing.Cut a length of tubing from stock by scoring round the tubing

at the point where it is to be broken, using a glass cutter or smalltriangular file. Wet the point to be scored and score the tube byplacing it on a mat and rolling it away under the glass file. Cover thetube with a cloth to prevent personal injury from glass splinters andbreak it at the score mark by pulling apart while bending it against athumb placed behind the mark.

Heat the length of tubing at its centre over a batswing burner,revolving the tubing all the while it is being heated. When pliabledraw the ends steadily apart while rotating to ensure uniformcooling. If drawn too fast a short jet tends to form and if tooslowly the jet may be of too large diameter. Finally the jets areseparated by scoring and breaking the thin section in half. The twojets should be lightly flame polished as should the cut ends of theglass tubing.

MatsHardboard squares about 0.3-0.5 ill square have been used

successfully as an alternative to the traditional asbestos mats. Thehardboard mats do not scratch the benches, are less brittle than theasbestos cement type of mat, and they are less likely to break upthan the soft asbestos mats (which, in any case, should never be used).Against the advantages is set a slightly increased fire risk. For thisreason it is inadvisable to use a sealant on the hardboard although avarnish or similar finish will increase the life of it. A fire resistantfinish is obtained by painting the mats with sodium silicate solution.

If asbestos cement type mats are to be used it is best to buythem ready cut. Asbestos dust, which develops when sawing asbestosis readily taken into the lungs where it causes damage to thetissues.

'Molecular' modelsExpanded polystyrene spheres are useful for making models of

crystal and molecular structures. The instructions given are forsimple tangential contact models. Instructions for more accuratemodels are given in the references.NC: Handbook for Teachers. Longman/Penguin, 1967NC: Sample Scheme Ill: A Course of Options, Appendixes toOptions 2 & 7. Longman/Penguin, 1967 .Platts, C.V. Instructional Booklet. Griffin & George Ltd.

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Sanderson, R.T. Teaching Chemistry with Models. D. Van Nostrand,1962.Tetlow, K.S.L. Modelling of Chemical Structures with ExpandedPolystyrene Spheres. Royal Institute of Chemistry Reprint, Vol. 1No.1 January 1964, Education in Chemistry.

The polystyrene spheres can be fixed together by dabbing thepoint of contact with trichloromethane (chloroform), propanone(acetone), amyl acetate or a number of other organic solvents andthen pressing together. A glue made of a polystyrene sphere dissolvedin a minimum quantity of amyl acetate may be used. Use theseorganic solvents and glues sparingly as they tend to dissolve thespheres. Commercially produced expanded polystyrene adhesive(EPA), obtainable at home decorating shops, does not dissolve thespheres but takes 24 hours to dry. Alternatively the spheres may bewired together or joined by toothpicks (wooden cocktail sticks),pipe cleaner, etc. A combination of physical linkage and glue makesa very firm permanent structure.

Make the linkages by cutting approximately 15 mm of connectingmaterial. Bore the points of contact using an awl or similar pointedinstrument and force the linkage into one sphere before forcing theother sphere onto the free end of the linkage. A dab of glue orsolvent applied before the spheres are finally pressed together thenfinishes the joint.

If spheres of different colours are to be used in the model, preparethem by making any holes needed and then colour them beforeassembling the model. Probably the easiest method of colouring thespheres is to use plastic emulsion paints or plastic emulsion whitebase and colourisers. Metallic substances may be indicated by usingaluminium paint mixed with appropriate colouriser. If in doubtabout any paint it is worth testing a sample on a spare piece ofpolystyrene to ensure that the paint does not contain a solventwhich will dissolve the plastic. Spheres may be dyed. Details aregiven in the Nuffield references.

Construction of body centred cubic lattice for Investigation A 8.18

This model is produced by making alternate layers 4 X 4 and3 X 3 spheres. When assembled the spheres of the 3 X 3 layers fitexactly over the spaces between the spheres of the 4 X 4 layer.

If the second 4 X 4 layer is displaced to make one 'side' a slopingflat face, this face is seen to be hexagonally close packed (see below).

An alternative construction produces a pyramid by using layers

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4 X 4,3 X 3,2 X 2, 1 XI, in which case the sloping faces arehexagonally close packed.

It is suggested that for permanent demonstration models 50 mmspheres may be used and the separate layers should be wired andglued.

Construction of diamond structure for Investigation 7.5

Fourteen tetrahedrally marked spheres are required for thisconstruction. The marks are mutually at 109.5° in tetrahedralstructures.

This is not the easiest of models to construct accurately and atemplate of some kind will be necessary in order to mark the spheresaccurately. The simplest template is the protractor type as illustratedfor the SUlphur (S8) model below, but marked at 109.5° and at120° .

Mark each sphere at 120° intervals around the equator (the seam)and then make marks for the connectors at the pole and on thelongitudinal lines passing through the pole and the equatorial 120°marks.

The diamond structure kit contains sufficient spheres forindividual pupils to construct a 14 sphere model or for pairs ofpupils to construct a larger model of 30 spheres.

Contents of the kit

3 m Pipe cleaner150 Polystyrene spheres, 25 mm diameter

Polystyrene glue5 Templates marked at 109.5° and 120°

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After marking the sphere, holes are bored using a compass pointor dissecting needle, and the spheres are connected using lengths ofpipe cleaner and polystyrene glue.

Construction of graphite structure for Investigation A 7.5The construction of this model is similar to that of ABA

hexagonal close packing. In this case, however the hexagonal ringsare made without a sphere filling the hole in the centre. Constructthree layers as shown in the diagram and connect the layers withtoothpicks so that the space between each layer is approximatelyequal to the diameter of the sphere being used.

graphite

Construction of hexagonal close packed lattice for Investigation A 8.18hexagonal close packed

layers 1 and 3 layer 2

It is worth joining only layers 1 and 2, keeping layer 3 separateso as to demonstrate both ABA and ABC packing systems. In thiscontext differently coloured layers will also be found to beadvantageous.

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Construction of simple cubic lattice for Investigation .4 8.18Make four layers each of 4 X 4 spheres. When placed directly

above each other the simple cubic lattice is produced. If displacedso that the layer above covers the spaces between the spheres of thelower layer, the body centred lattice is produced.

Construction of the S8 sulphur structure for Investigation 6.24Two models are useful; a chain of eight spheres joined by rubber

cord as shown in diagram A, and a 'rigid' ring structure as indiagram B. The rigid structure may also be joined with rubber cord.

(a) (b)

In order to produce these models a template is made as shown inthe diagram below. The cut-out semicircle is equal in diameter tothe size of sphere used in the construction.

template for sulphur

Mole kitThe mole kit is used in Investigations 7.12 - 7.16 inclusive.

Contents of the kit per pair of pupils1 Polystyrene sphere, coloured blue, 18 mm diameter1 Polystyrene sphere, coloured yellow, 25 mm diameter

Polystyrene sphere, coloured red, 32 mm diameter100 Polystyrene spheres, white, 12.5 mm diameter

Polythene bag, opaque, containing 6 blue spheres1 Polythene bag, opaque, containing 6 red spheres1 Polythene bag, opaque, containing 6 white spheres

Polythene bag, opaque, containing 6 yellow spheresPolythene bag, opaque, empty, of same size as the full bags.

Polythene bag, transparent, containing 6 g carbon1 Polythene bag, transparent, containing 12 g magnesium1 Polythene bag, transparent, containing 16 g sulphur1 Polythene bag, transparent, containing 20 g calcium1 Polythene bag, transparent, empty, of same size as the full bags.

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The polystyrene spheres must all have been bought from the samesupplier since there are slight differences in the density ofpolystyrene used by different manufacturers.

The empty bags are used to compensate for the mass of the bagwhen full bags are weighed.

Other apparatus required

Access to a balance reading to 2 places (e.g. top pan)Balance, simple lever type, Nuffield Physics item IOc, fitted withtwo light scale pansRetort stand, bosshead, and clampRule, 300 mm

Oil film kitThis kit is required for Investigation 6.15 and is based on the

Nuffield Physics Oil Film Kit, item 7.Note that the Nuffield kits were designed for class sizes of 32

pupils. Some firms produce quarter class kits which apply well tothe groups of ten pupils on which the required quantities ofequipment for the Integrated Science Project are based.

Contents of the oil film kit required per 10 pupils4-6 Booms, metal, 350 mm long, coated with blackened paraffin

wax10 Graticules, 20 mm scale X 0.5 mm (NP item 7 E)10 Hand lens holder with clips for graticule and mounted wire

loop (NP item 7G)10 Mounted wire loops (NP item 7 F), 44 s.W.g. (see Appendix 1

'Standard wire gauge') steel wire, 75 mm long, mounted oncard.Powder sprinkler containing Lycopodium or talc

2-3 Sponges, for mopping up spillages and cleaning trays2-3 Trays, minimum size 300 mm square, black polythene, or

metal coated with blackened paraffin wax8-12 Wedges, rubber, plastic or wood, for levelling trays10 em- Olive oil

Other apparatus required2-3 Beakers, 10 crrr' or solid watch glass to contain the oil2~3 Buckets, for filling and emptying trays10 Hand lenses, X 8 or X 10 folding2-3 Metre rules

Detergent, for washing up

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The apparatusEssentially the experiment requires an oil drop of measured

volume to be spread on a water surface. The oil drop is producedusing mounted wire loops held in the composite hand lens holder.The diagram shows a simple construction for such a holder. Allsizes are approximate, as actual dimensions depend upon thecharacteristics of the equipment used. The clip for the wire loop ismounted on the upright wooden block so that the loop isimmediately above the graticule when mounted. The exact positionof the large Terry clip depends on the focal length of the hand lensused. It must be possible to see both the graticule scale and the oildrop on the wire loop in focus when the hand lens is in place.

bulldog clip to hold ----+mounted wire loop

Terry clip to holdhand lens

composite hand lens holdersmall Terry clip to hold graticule

0.5 mm diameter oil drops may spread to over 300 mm whenplaced on the water surface so the tray should ideally be wider thanthis minimum. Any traces of oil or detergent on the tray will ruinthe experiment so both it and the metal booms must be scrupulouslycleaned. To determine when the tray is completely clean, and toshow up the surface, it is coated with paraffin wax coloured blackby mixing with vegetable black. This coating is applied to both thetray and the metal booms by painting on molten wax with a paintbrush. Irregularities in the surface can be flame smoothed by using aBunsen burner, providing this is done carefully and the tray is notallowed to become too hot. Black polythene or polypropylene traysdo not need to be wax coated.

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Two or three attempts may be made at a time providing thewater surface is swept clean using the wax covered booms. Effectivecleaning of the surface is only possible if the level of the water isabove the edge of the tray. The wax coating helps to preventspillage of water.

The tray is cleaned with a detergent such as Teepol which is thenwashed off with running water until no wet patches appear on thewax surface. Patches which do not wash off with water are caused byoil and need to be treated with detergent and washed again. Caremust be taken not to touch the tray or water surface with thefingers.

Only a sufficient quantity of powder used to show up the watersurface should be sprinkled over it. Too much powder will hinderthe experiment. Sprinklers for the powder are easily made by holdinga double thickness square of.butter muslin over the end of a specimentube containing the powder and fixing the muslin in place with arubber band.

Personal weighing machinePersonal weighing machines are sets of bathroom scales calibrated

in newtons.

Recalibration of bathroom scales

1. Invert the scale so that the platform is in contact with the bench.

2. Use a screw driver to release the loops of the springs (or screwsif fitted) which hold platform and base together.

3. Remove the base, invert it and place it beside the platform. Notethat in some types the balance assembly is permanently mounted onthis base and is removed with it.

4. Remove the balance assembly and place it on the base plate lugs,ifit is not-already attached to the base.

S. Remove the metal scale disc by unscrewing the nut at its centreand cut a card disc to the same size.

6. Calibrate the card using the table appropriate to the balance,.andsecure it to the metal disc, ensuring that the zeros coincide.

7. Replace the recalibrated disc on the balance assembly makingsure that the lugs pass through the holes in the disc and that thepointer is above it and near zero on the new scale. Secure the discassembly.

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8. Pass a loop of string through each of the spring loops used to holdbase and platform together.9. Invert the balance assembly and replace it on the free lugs insidethe platform.10. Invert the base plate, Pass the string loops through the holes init and replace it on the balance assembly using the string loops tohold the springs taut.11 . Use the string loops to pull through the spring loops and securethem to the base plate.12. Remove the string. Invert the balance and reset.the zero.

Conversion tables for balance reading to 20 stones (1240 N)Note that in some balances the scale occupies 3500 of the dial and not 3600

Reading in newtons 0 AO 80 120 160 200 240 280 320Angle in degrees 0 12 23 35 46 58 70 81 93

Reading in newtons 360 400 440 480 520 560 600 640 680Angle in degrees 104 116 128 139 151 163 175 186 198


Reading in newtons 1080 1120 1160 1200 1240Angle in degrees 314 326 337 348 360

Conversion tables for balance reading to 18stones (1120 N)Note that in some balances the scale occupies 3500 of the dial and not 3600

•


Reading in newtons 360 400 440 480 520 560 ·600 640 680Angle in degrees 116 128 141 154 167 180 193 206 219

Reading in newtons 720 760 800 880 920 960 1000 1040Angle in degrees 232 244 257 270 283 296 309 335

Reading in newtons 1080 1120Angle in degrees 348 360

Propagator

Living materials are frequently seasonal. The use of a heatedgreenhouse can do much to free a course from seasonal influences.

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The propagator described should help overcome some of theproblems of obtaining plants out of season if a greenhouse is notavailable.

The propagator consists essentially of a water-tight trough about100 mm deep with a simple framework above to support a polythenecover and the lighting system. About 0.7 m2 (8 square feet) ofgrowing space should be provided by this trough. The apparatuscould be made to stand on a bench or table or could be madefree-standing by fitting legs. Since the propagator will be sitedindoors, the temperature is likely to rise slightly higher than that ofthe room in which it is placed due to the heating effect of the lights.The best position will probably be in a shaded, cool part of thework area, or in a suitable store room.

The propagating frame's trough and legs can be built from60 mm X 35 mm (2~ in X 1~ in) Handy angle or Dexion girder ineither alloy or steel, with the top construction of 35 mm X 35 mm(I ~ in X 1~ in) angle girder; or, from softwood using 25 mm X25 nun (1 in X 1 in) for the top frame, 75 mm X 25 mm (3~ in X1 in) or 100 mm X 25 mm (4 in X 1 in) for the trough, 50 mm X25 mm (2 in X 1 in) for strengthening the frame and legs, and50 mm X 50 mm (2 in X 2 in) for the legs.

The floor of the trough may be made from a variety of materials,Alloy or steel shelving bolted to the angle girders or equivalentwooden sides, or tongued and grooved 125 mm (5 in) floorboarding

156

should need no other support; but if corrugated PVC roofingmaterial, or hardboard is used then struts will need to be fittedunder the shelf. In any case, unless a glass fibre trough is made, thewater proofing is ensured by means of a sheet of polythene whichwill overlap the edges of the trough.

The covers are made from polythene sheeting which is securedon three sides and the roof but left loose for access on the fourthside. If the propagator develops too high a temperature (above24°C) it may be necessary to perforate the top cover and even tofit a small fan.

After construction the trough should be filled to a depth of40 mm with clean gravel and topped up with 25 mm of sand. If acoffee can or polythene bottle with base and lid removed is placedin the trough (diagram B) the method of capillary watering may beemployed.

Strip lighting is recommended for use but it is expensivecompared with tungsten filament lamps. Three 1.22 m (4 ft) 40 WGrolux tubes plus one 40 W tungsten filament lamp will be ideal forthis sized frame (diagram A) and if mounted in a separate subframethe lights could be lowered for seed germination experiments and forlow growing plants. Two 100 W tungsten filament lamps connectedin series could replace a single 40 W lamp and when connected in thisway would supplement the light emitted in the red end of thespectrum. The sub frame for the lights is made about 50 mm longerthan the main frame and is supported on the top frame. The heightcan be adjusted by the insertion of additional cross battens (shownas broken lines in diagram A) across the sides of the main frame atappropriate heights.

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The length of the simulated day is important and is easiestcontrolled by a 24 hour electric clock timer. The photoperiod(the length of time for which the plants are illuminated) has animportant influence on flowering, the size and colour of leaves andthe elongation and branching of stems. Different photoperiods arerequired for different types of plant. Most of the popular houseplants grow well with 16 hours of illumination. Ultraviolet light isharmful to plants but may be filtered out by the insertion of a sheetof glass between the light sources and the plants.

References

Apparatus Guide. NSSTechnology brief 44, Gardening Under Lights. Schools CouncilPublicationsLeaflet on Grolux tubes. Thorn Lighting Ltd.

Pumps and associated apparatus

Vacuum pump

In order to protect the pump a water trap should be insertedbetween the apparatus and the pump. An easily assembled form oftrap consists of a u-tube held by a retort stand, bosshead, and clampadjacent to the pump. Freshly roasted calcium chloride or silica gelacts as the desiccant and this is prevented from being drawn into thepump by the insertion of rocksil plugs between it and the u-tubeoutlet.

Water in the pump leads to corrosion of metal surfaces and alsoimpairs the efficiency of the vacuum oil. Water traps should befitted whenever the pump is to be used in the presence of water orwater vapour (e.g. when filtering solutions through a Buchner funnel).

For most efficient usage the pump should be regularly checkedand maintained according to the manufacturer's instructions. If thepump has been unused for some time it should be specially checkedbefore it is required in case it has corroded. Failure to start isprobably due to corrosion. Switch off immediately to protect themotor. It is sound practice to run vacuum pumps regularly (e.g. forten minutes once a week).

158

Filling balloons with gasesIf gas cylinders are not available connect the pump by its inlet to

a source of the gas ( a large polythene bag, not a gas generator) andinflate the balloons which are connected to the pump outlet. Gasesshould be dried before entering the pump. Do not use this methodfor corrosive or oxidising gases.

Push-pull forcemeter construction

The forcemeter described here may be suggested for the pupils toconstruct in Investigation 1.9.

broom handle

""'''I--Iarge cuphook

scale

![.~~<,~~~~=~I

I <--\_ ----"",I.

_ 400mm

The diagram shows the simplest way of assembling this instrument.The range will depend on the number of rubber bands employed, andthe calibration needs to be checked before use as the elasticity of thebands varies with age and usage. Refinements such as the use ofsprings instead of rubber bands, and stops made from hardboarddiscs (40-50 mm diameter) might be employed for a few laboratorymodels but it is suggested that with these refinements the instrumentbecomes too expensive for the pupils to make and take home.

A smaller model which may be regarded as suitable for pupilmanufacture employs a 150 mm length of 7.5 mm dowel with asmall screw hook, a sleeve made from a cardboard thermometercase, and rubber bands.

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Standard wire gaugeThe standard wire gauge (s.w.g.) is related to metric and imperial

measures as shown in the table.

s.w.g. Diameter Diameterfinch fmm

10 0.128 3.2512 0.104 2.6414 0.080 2.0316 0.064 1.6318 0.048 1.2220 0.036 0.91422 0.028 0.71124 0.022 0.55926 0.018 0.45728 0.0148 0.37630 0.0124 0.31532 0.0108 0.27434 0.0092 0.23436 0.0076 0.19338 0.0060 0.15240 0.0048 0.12242 0.0040 0.10244 0.0032 0.08146 0.0024 0.061

Two-dimensional kinetic model kit

This kit is used in Investigations 1.6, 6.2, 6.5, and'" 6.6. It is basedon the Nuffield Physics Kit, item 12.

The numbers of items required are applicable to groups of tenpupils.

Contents of the kit per ten pupils400 Marbles, approximately 16 mm diameter

20-30 Marbles, approximately 25 mm diameter5 Match boxes, approximately 50 mm X 35 mm X 20 mm5 Trays, approximately 300 mm X 200 mm X 20 mm,

cork lined5 Wooden partitions to fit width of tray

Note that if Nuffield kits are purchased there will be insufficient16 mm marbles.

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Spectroscope handlingIt is difficult to hold the direct vision spectroscopes steady

enough to observe flames from flame test wires. The flame persistsfor a short time only. If the spectroscope is clamped it is possible tolook through it at the flame before the flame test wire bearing thetest substance is inserted into it.

The duration of the flame can be extended by using the apparatusshown in the diagram.

I-"-----ll----catdboard thermometercaseaswick(or asbestospaper)

"---glass tubing

---salt solution

---rubber bung

"---barrel ofBunsenburner

If possible, hard glass tubing (e.g. Pyrex) should be used in theconstruction of this apparatus. Glass tubing may be cut using the hotwire technique - see Appendix 1 'Hot wire glass cutting technique'.Boring of bungs is described in Appendix 1 'Bungs'.

By using saturated salt solutions a persistent and reliable flame isproduced. If several solutions are to be used it is worthwhile settingup a separate set of apparatus for each solution and allowing theclass to circulate to see each one, rather than having one set in whichthe solution and cardboard wick have to be changed.

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Appendix 2 Notes on biologicalmaterials

This appendix is mainly concerned with hints for the culture andmaintenance of organisms. It is helpful to have a special animalroom, apart from the main work areas. A greenhouse is advantageousfor the culture of plants, but in its absence some sort of propagatorwill be found useful - see Appendix 1 'Propagator'.

The point needs making that organisms are alive and aresusceptible to disease and death. They need constant care andoverseeing, and will not survive long periods without attention,such as occur over holidays. When organisms are diseased it isusually more humane to kill than to try and cure them. The killingprocedures described should not cause distress to the organismsconcerned.

It is worth checking all cultures daily and where incubationprocedures are involved the setting of the incubators should bechecked frequently. Strict cleanliness should be observed whenhandling cultures in order to prevent cross contamination or selfinfection through handling them. Always wash hands well withsoap and water after dealing with animals.

The information given concerning culture methods has beentried and tested, but it is not claimed that the methods areinfallible nor that they are the only correct ones. There are oftenvariations on these methods and different technicians are likely tohave their own favourite and effective procedures.

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Agars and brothsBroth media are mixtures of nutrients in water. They remain

liquid when prepared and organisms grow throughout the medium.Agars are mixtures of nutrients made into a jelly with agar and

water. Organisms usually only grow on the surface.Media are usually in powder or tablet form. All that is required

is to add appropriate quantities of water according to the directionswhich are usually printed on the bottle label. The medium is mixedthoroughly and then sterilised.

The necks of containers should be sterilised by flaming in aBunsen burner flame after the top has been removed and before themedium is poured from them. Petri dishes should be uncovered foronly as long as it takes to fill them with medium. Allow 10-15ern> of medium for each 90 mm diameter Petri dish.

Take care to keep media sterile during transfer.Condensation can be avoided by pouring the agar as cool as

possible and stacking plates on top of each other. Any condensationwhich forms on the plates or the covers can be removed before useby drying them in an oven or incubator without a fan. Set the ovenfor 37-40°C. Open the Petri dish quickly and place both halvesopen side down. Place the bottom half on the oven shelf and rest thetop half over it. Leave until most of the cloudiness disappears.Dried plates cannot be stored for later use.

, incubator shelf

diagram showing position of dish during drying

Prepared plates can be stored in a refrigerator until required. Putthe plates in a polythene bag which can be sealed. Mark all plates withthe media initials, e.g.

NA = nutrient agar,GNA = glycerol nutrient agar.

Incubate plates infected with bacteria with the lids down andwith lids up for fungal cultures.

Infected medium should be burned after use and the containersmust be sterilised. Medium can also be rendered harmless by

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autoc1aving (or soaking in disinfectant for 24 hours) beforewrapping and disposing by burying or in the dustbin.

Making streak plates

Sterilise an inoculating loop (see Appendix 1 'Flame test wires')by making it red hot in a flame and allow it to cool. Open the stockculture bottle quickly and pass the opening two or three timesthrough a flame. Touch the inoculating loop to the material (usuallya broth or a slope culture) which is to be streaked out. Colonies ofbacteria should be visible on a slope.

Lift the lid of a prepared Petri dish and keep it above the bottomto protect the medium from falling dust. Pass the loop through thegap between the lid and bottom of the dish and lightly touch theagar surface making a zig-zag movement across it. Try not to breakinto the agar. Replace the lid and turn the dish through 90°Repeat the procedures described; resterilise the loop, pick up moreof the culture, open the dish and repeat the zig-zag movement toproduce a criss-cross pattern of streaks.

Incubate the plates by stacking the dishes, lids down, in anincubator set at 37°C for 24-36 hours. Colonies should be growingover the areas touched by the loop.

Note that ultraviolet (u.v.) light kills bacteria, so keep all culturesout of direct sunlight and preferably in complete darkness.

MediaMedia should be made up exactly as directed. Tap water is often

better to use than distilled or de-ionized water as it affects the pH(degree of acidity/alkalinity) less. Resterilisation of media should beavoided as each heating tends to make them more acid, and alsocauses darkening due to sugars becoming caramelised.

Blackened agarThis is used for Investigationa 4.11 for the growth of tobacco

seedlings.Add 30 g of agar and 3-5 g of vegetable black to 1000 ern> of

water. Mix the ingredients while boiling. This provides sufficientmedium for 50-75 dishes.

Sterilise at 105 N rrr? (15 p.s.i.) for 15 minutes in an autoclave.When cool, but not solid, pour into sterile glass or plastic Petri

dishes, putting 15-20 em> of medium into each dish.

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Glycerol nutrient agarThis agar is used in Investigationo 4.10 for the growth of the

bacterium Serratia marcescens.To produce sufficient medium for ten dishes mix;

2 g Agar6 em" Glycerol0.3 g Meat extract (e.g. Brand's Essence)1 g Peptone0.5 g Sodium chloride (analytical quality)

100 em> WaterBoil the ingredients to dissolve the agar and adjust the pH to 7.2

using 1 M sodium hydroxide solution - see Appendix 3.Filter through cotton wool and sterilise at 105 N rrr? (15 p.s.i.)

for 15 minutes in an autoclave.Pour 10-15 crrr' into Petri dishes when cool but not solid.An alternative preparation uses nutrient agar pellets or powder

which are made up according to the manufacturer's instructions.Before sterilising add 6 ern" glycerol to each 100 ern" prepared.

Glycerol nutrient brothThis broth is used to grow broth cultures of Serratia marcescens

ready for transfer to agar. Make up as for glycerol nutrient agar, butomit the agar from the recipe.

Sterilise by autoclaving at 105 N rrr? (15 p.s.i.) for 15 minutes.

Nutrient agarThis agar is required for Investigatioric-a.I O.Make up according to the instructions for glycerol nutrient agar,

but omit the glycerol.In both of these agars an alternative and easier method is to use

the commercially available nutrient agar tablets or powders and inthe case of the glycerol nutrient agar to supplement the mixturewith glycerol at the rate of 6 em> per 100 cm-' of water added.

Nutrient brothThis broth is used to grow cultures before transfer to agar plates.

Make up as for nutrient agar, but omit the agar.

Sterilisation with chemicalsProprietary disinfectants should be used according to the

instructions supplied with them. Lysol and carbolic (phenol) basedsubstances are generally used in 5% solution. Items to be sterilised

165

should be soaked for 24 hours. Care should be taken with phenolbased disinfectants that they are not too dilute because micro-organisms can use the dilute phenol as food.

Chlorine derivatives such as sodium hypochlorite (e.g. Milton,Brobat, Voxan) are usually used as 10% solutions and act morequickly than phenol based disinfectants. Soak for 12 hours to ensuresterilisation.

Cetrimide (e.g. Cetavlon) is used as a 1% solution for 24 hours.Generally chemicals are used to sterilise used dishes, instruments,

plates, etc. If used to sterilise glassware prior to work care must betaken in rinsing, draining and drying before use. This method can beused on plastic Petri dishes which cannot be autoc1aved.

It is useful to have a bucket containing disinfectant available forsessions using micro-organisms, into which all apparatus and culturescan be dropped, by the pupils, after use.

Sterilisation by flaming and dry heatDip slides, spatulas and instruments in meths and burn off in a

Bunsen burner flame. Allow to cool before using.Heat loops and instruments in a Bunsen burner flame until they

are red hot. Allow to cool in a propped up position before use. Useimmediately on cooling.

A hot air oven is suitable for glassware. Plug pipettes, test tubes,etc., with non-absorbent cotton wool. Wrap them up in suitablysized pieces of aluminium foil, either individually or in convenientpackages. Place in a cold oven and raise the temperature to 160°C.Keep at this temperature for an hour and allow the oven to coolbefore removing the packages. Packaged glassware will remain sterilefor several weeks. Temperatures higher than 160°C will cause thecotton wool plugs to scorch.

Sterilisation by lightThe ultraviolet portion of sunlight will kill bacteria on surfaces

and in media. Bacterial cultures should not, therefore, be kept indirect sunlight.

Ultraviolet light can be used to sterilise plastic Petri dishes. Thedishes are spread under a TUV lamp (placed 0.5 m above them)which should be left on for 24 hours or more before the dishes areto be used. The lamps are harmful to humans and should be shieldedor only switched on when the room is empty.

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Sterilisation by moist heatBoiling for ten minutes will kill all sporing organisms but leave

their spores unaffected. If two parts per hundred of sodium carbonateare added and the boiling is continued for thirty minutes, sporesalso are killed. The method is suitable for instruments and can beused for media. Media are boiled in loosely closed containers. forthirty minutes on each of three successive days. Prolonged boiling(2-4 hours) may not kill all spores.

Steam under increased pressure in an autoclave or pressurecooker at 105 N rrr? (15 p.s.i.) produces a temperature of 121°C.Small items will be sterilised in fifteen minutes, bulky items andlarge quantities of media may take over thirty minutes.

Containers for media about to be sterilised should be no morethan half filled to allow for expansion. Plugs or screw tops shouldnot be tight. Conical flasks fitted with loose non-absorbent cottonwool plugs are useful for sterilising large quantities of medium.Autoclaves must be allowed to steam for five minutes to expel allair before bringing to pressure. Start timing when the autoclavereaches the required pressure. After the sterilising time theautoclave must be allowed to cool and the pressure must beequalised with atmospheric pressure before the instrument isopened.

AmoebaLive Amoeba is suggested as an organism for Investigation

~ 5.2. It is easiest to obtain fresh cultures from biological suppliersas required rather than maintaining cultures within the school.

Amoebae are more difficult organisms to keep than Paramecia.They require dim light, a temperature of IS-22°C, and boiled,filtered pond water or Chalkley's medium.

Culture mediumChalkley's medium is prepared by dissolving:

1.2 g Calcium chloride (analytical quality),0.8 g Potassium chloride (analytical quality),20 g Sodium chloride (analytical quality)

in 1000 em 3 of glass redistilled water.The food medium consists of boiled wheat grains which are

allowed to stand in the culture vessel with the culture medium forseveral days until they have a furry appearance. At this stage themedium is inoculated with Amoeba.Put 2-4 wheat grains into eachculture vessel and subculture once a month by dividing medium and

167

food between two dishes and making up the volume with freshmedium. Each subculture should have another wheat grain addedwhen it is set up.

Culture vessels

Crystallising dishes about 50 mm deep and up to 100 rrimdiameter make ideal culture vessels. They should be filled to a depthof 35 mm with culture medium and be covered with a glass plate.

Soil AmoebaeSoil Amoebae are easily obtained but are much smaller than

those obtained from suppliers. They can be obtained by placingloam soil in some water in a beaker and leaving for two weeks. Afterthis time remove some surface scum and some sediment and spreadit on an agar plate (1.5 g agar, 0.1 g peptone, 100 ern> water).Numerous Amoebae should be found among the bacteria whichdevelop and grow on the agar.

ClonesClones of Coleus, dandelion and Zebrina are suggested for

Investigation 4.9.A clone is a group of organisms which have been propagated

asexually (vegetatively) from a single parent.Clearly label all plants reproduced by vegetative means and keep

the parent plants for comparison.Coleus cuttings are taken from young shoots just below a node.

A node is the junction of stem and leaf. The cuttings are planted inpots containing a suitable compost. John Innes potting compost No.1is very satisfactory and is available from most gardening shops andchain stores which deal in gardening equipment. Use clay pots andplant near the side.

A suitable compost can also be made by mixing three parts ofgood sieved loam with one part of peat or leaf mould and one partof washed sharp sand.

Dandelions are dug out of the garden and the long tap roots arecut into approximately 35 mm lengths. It is important that eachpiece of root should have a side root(s) growing from it.

The roots are planted in compost in plant pots. The compost usedfor Coleus is suitable.

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cut end 5mmbelow leaf node

cutting of Coleus cutting of dandelion cutting of Zebrina

Zebrina [Tradescantia) is a popular house plant which makes rootreadily in water or in compost. Cuttings are taken just below nodesand the cuttings can then be potted or could be potted as soon asthey are taken. Compost can be the same as that described forColeus.

If no greenhouse is available a propagator will be useful forgrowing these plants - see Appendix 1 'Propagator'.

Drosophila melanogaster, fruit fly.The fruit fly, Drosophila is a small fly well known to amateur

winemakers as the vinegar fly. These flies are attracted to ripe andover-ripe fruit and will congregate around mashed bananas. Theflies can be collected by leaving a jar of mashed banana outside on a-summer's evening but with the availability of recognised strainsfrom biological supply houses the effort is hardly worth while. Theorganism is required for Investigations=Lfb and 4.9.

Culture mediumThere are many different formulations of culture media for

Drosophila ranging from simple fruit pulps to highly sophisticatedspecialities. The particular formulation given here has provedsuccessful in trials, as too have some of the commercially availableready mixed and sterile media. Fruit pulps are not recommended asthey have a tendency to rot and promote fungal growths whichresults in wastage of cultures.

169

The recipe given is sufficient for 20 one-third pint orange juice ormilk bottles.

30 g100 g50 g26 g

1000 em"

Agar powderOatmeal (breakfast oats)Soft brown sugar or 40 em? black treacle (molasses)Yeast, driedDistilled water

Mix the ingredients together and bring to the boil while stirring.Simmer until a uniform consistency is obtained, stirring continuously .

In order to help prevent the medium from growing moulds itshould be sterilised in an autoclave - (see Appendix 2 'Agars andbroths') - and may also be treated with Nipagin. Conflicting reportsconcerning the efficacy of this chemical' exist and the alternative,propionic acid, seems not to work. Nipagin (methyl-p-hydroxybenzoate or n-propyl p-hydroxybenzoate) is prepared bydissolving 0.5 g of solid in 2 ern> ethanol. This solution is dilutedto 80 em> with distilled water. The solution is added to the foodmedium just before it is added to the culture bottles.

Sterile culture media may be kept in a refrigerator for about sixweeks or in a deep freeze for about six months when protected fromdesiccation by storing in a sealed polythene bag.

Culture bottles and specimen tubes

Before use containers should be washed out well with hot waterand disinfectant such as Izal or Lysol (5% solution), but care must betaken with the hot disinfectant, which may be caustic. They thenneed to be rinsed well with clean water before filling with culturemedium and sterilising.

.--------cotltomll/Ool stopperenclosedin muslin

I+-!!----filter paperpushedinto culturemediumwith glassrod

30-50mm {deep --- culture medium

t pint milk bottle

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The culture medium is poured into the bottles whilst still hot andfluid. A 50-80 mm X 25 mm length of grade 3 filter paper is foldedin half lengthwise and pushed into the medium using a clean glass rod.The bottles are stoppered with non-absorbent cotton wool coveredwith muslin or with foam plastic stoppers.

One-third pint orange juice or milk bottles are suitable for stockcultures. For investigationA3.7b three or four sets of these cultureswill be needed. Each bottle should be labelled with the date andnumber of flies used to start the culture. New cultures should bestarted at weekly intervals up to the time required.

After sterilisation allow the medium to cool and then add alittle granular dried yeast to the medium in each bottle just beforeadding the flies. Since the flies will be unconscious when added tothe bottles the yeast is powdered and sprinkled over the surface ofthe food medium so that the flies do not become stuck. The yeastis also required so that the medium will ferment.

Handling of fliesIt is best to use at least five to ten pairs (male and female) of

flies to start a stock culture. Each female on average will produceabout 80 offspring. If sexing proves difficult an initial stock of10-20 flies should ensure the presence of males and females

There are three methods of immobilising flies for transfer:-using ethoxyethane, using carbon dioxide, and refrigeration. Thestandard method is to anaesthetise the flies using ethoxyethane(diethyl ether) in special etherisers. The ether is put on thecotton wool, inside the etheriser, so that it is damp but not saturated.When flies have been transferred to an etheriser the apparatusshould be rotated while watching the flies until none of them move.Quickly empty the flies onto a sheet of filter paper and sort out theones required using a brush. Place the unconscious flies on the filterpaper strip inside the new culture bottle. Close the bottle and lay iton its side (so that the flies do not fall onto the sticky medium) untilfully recovered.

If large quantities of flies are to be transferred by this method donot try to .make them all go into the etheriser at the same time butdeal with them in batches. The ethoxyethane can be diluted bymixing with ethanol so that there is less danger of over etherising.Notes on etherisers are given at the end of this appendix item.

Flies may also be rendered unconscious by treating. them withcarbon dioxide from a gas cylinder. Do not use a gas generator asthere is a chance of killing the flies with acid fumes from the

171

gas-producing reactants. The carbon dioxide treatment is safer thanetherisation and most of the flies will recover. An emergencyetheriser will be required in addition to the source of carbon dioxide.The gas is let into the culture jars by means of a hypodermicsyringe needle which is inserted through the stopper. The needle isconnected to the gas cylinder by means of rubber connectingtubing, and the gas must be supplied slowly.

If the culture bottles are placed in a refrigerator for up to half anhour the flies can be easily handled. Should they recover too quicklyduring sorting operations, have an emergency etheriser nearby.

In all cases it may be advantageous to keep the culture bottlesand tubes on their sides until the flies have recovered so that they donot become stuck to the food medium. Flies which escape into thework area may be trapped in a narrow necked jar fitted with afilter funnel and containing mashed banana. It is easier, however, touse a fly spray and write off the escaped organisms.

Keeping culturesKeep the stock bottles on trays holding six to twelve bottles

each. They may be easily stored, inspected and handled when onthese trays. Label each bottle with details of the strain, the date ofstarting the bottle and the genetic cross (if this is involved). In orderto reduce the risk of infection of cultures by mites it is ad visable tostand the bottles in Petri dishes containing motor oil (e.g. SAE 30).

Drosophila breed best at 25°C. They become sterile if kept above28°C for any length of time and the rate of reproduction isSignificantly reduced below 15°C. It is best to keep them in areliable incubator. Normal room temperatures are usually adequateproviding the cultures are not kept on window sills where thegreatest temperature fluctuations tend to occur. Rapid changes intemperature cause condensation in the culture bottle. Flies becomestuck to this and die.

Life historyAt 25°C the adult hatches from the pupa approximately nine

days after the egg is laid. Females can lay eggs twelve hours afteremergence (sometimes this is 48 hours if the flies have "beenetherised). Males are potent three hours after emergence. Theaverage length of adult life is 26 days for females and 33 days formales. Allow for a life cycle of 12-14 days in planning work. If thecultures are not kept in an incubator at this temperature the timesquoted are likely to be incorrect with all stages taking much longer.

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Sexing the fliesTo obtain virgin females all the adults are removed from a

culture. Any flies emerging in the next eight hours are likely to bevirgins. Under school conditions a suitable and reliable procedure isto remove the adults first thing in the morning and then remove thevirgin stock at lunchtime and again immediately after school.Separate the males from the females as soon as possible and keepthem separate until required. (Virgin flies are not required for.•..3.7b).

female male

dorsalview

ventralview

ventralview

sideview

'features to distinquish between male and female Drosophila

173

Young virgin females have a pale, almost white, body colour.They tend to hatch earlier than the males. When in doubt the absenceof the sex comb (see diagram) should be used to confirm identification.Other criteria for sexing are the brown chitinised claspers at the endof the abdomen 'of the male but absent in the female. The dorsalsurface of the male's abdomen is darkly pigmented at the posteriorwhile in the female this dark hind portion has lighter bands acrossit.

EtherisersEtherisers are easily prepared from specimen tubes and small

filter funnels as shown in diagram (A) below. Diagram (B) shows acommercially available etherizer in which the side arm may be usedeither for adding ethoxyethane or for pouring out the flies.

In either case the ethoxyethane may be diluted with ethanol andonly sufficient should be added to moisten and not soak the cottonwool.

---filterfunnel,---- ..•••.diameter65mm

l;;;'>j'~-- cotton wool soakedin ether

t----specimen tube150mmx25mm

A B

the ethershould moistenbut not saturatethe cotton wool

Emergency etherisers are easily made from the bottoms of plasticPetri dishes to which the cotton wool, dampened with ethoxyethane,will stick due to the solvent making the surface of the plastic tacky.These etherisers should be kept open side down on a surface notaffected by the ethoxyethane vapour.

174

Using etherisersAdd a few drops of ether to the cotton wool so that it is damp

but not saturated.Shake the culture bottle or knock it gently on a cork mat so that

the flies are kept away from the mouth of the bottle. Too muchshaking or knocking may make the culture medium fall out, andflies may then stick to the medium or to any moisture on the glass.

Quickly remove the bung from the culture bottle and place theopening of the bottle over the funnel of the etheriser. A gentle tapon the bottom of the culture bottle will make the flies pass into theetheriser.

I~--final position of t pintmilk bottle

putting flies into the etheriser; the movementsshould be performed as quickly as possible

175

As soon as the flies are removed from the culture bottle and arein the tube of the etheriser, remove the funnel and replace it with astopper. If large numbers of flies are to be etherised do not try totransfer them all at one go but take out several batches until thebottle is empty.

The flies are usually anaesthetised very quickly and are soonready for examination.

If at any stage flies are seen with their abdomens arched, theirlegs bunched together, and wings stretched over their backs it is asign that some flies are dead due to the use of too much ether.Immediately take the funnel off the etheriser and replace it with astopper. Shake any flies in the funnel back into the culture bottleand replace the bung. Start again using less ether.

Petridishbottom,

ethensedcottonwool------i I(_::=:_3 1l .. '-.=:~,J

Place one edge of the emergency etheriser just in front of theflies and quickly close it over them. Do not rush the movement orthe flies will be blown away.

Hay infusion

This infusion is useful as a culture medium for micro-organismssuch as Paramecium which is suggested as an optional organism forInvestigation a 3 .7b.

Nearly fill a plastic aquarium with water and add about twelvehandfuls of hay with some of the stalks protruding through thesurface into the air. After a few days inoculate the aquarium withseveral cubic centimetres of pond water.

176

The vegetation helps to preserve unbroken the surface film ofbacteria; such undisturbed conditions tend to promote the copiousgrowth of infusoria.

Should hay not be available then dead leaves of trees such as elmmay be used as an alternative.

Hay infusions may also be produced by autoclaving a mixture ofvegetation and water so producing a sterile medium. This procedureis not necessary unless the medium is required to be kept for sometime. For .A.3.7ba sterile medium is prepared which is reinfected byair borne bacteria by leaving it uncovered for several days. When abacterial scum has formed the medium is inoculated withParamecium.

Mice

Hands must be carefully washed with soap and water afterhandling mice in order to reduce the risk of transferring diseaseorganisms either to other animals or to oneself.

Keeping mice

Mice are best kept in shallow cages with separate areas for nestingand feeding.

The 'Cambridge' cage consists of a plastic (polypropylene) troughwith internal dimensions 275 mm X220 mm X 80 mm. It is coveredby a wire lid sloping down towards the centre of the trough. On thelid a metal plate acts as a cover to the nesting area. A half-pint milkbottle supplies water .

. Six to nine adults can be kept in one cage. For breeding, a trio oftwo does and a buck can be kept in a cage. The does can nurseseveral litters at the same time, but if the litters are of unequal age,and equally if one of the mothers tends to eat her young, it is best toseparate the does for parturition (birth) and nursing.

Cages can be kept on racking made of metal strips or woodenbattens fixed to a wall. A space of 165-180 mm is needed betweenshelves and a space of 50 mm between adjacent cages. Three shelvesof four cages each will occupy a wall area of about 1.2 m wide by0.6 m high and will project about 0.3 m.

A room temperature of around 20cC and reasonable ventilationwith no draughts is desirable. Each doe should have her own recordcard which is clipped to the cage by a spring clip. If these are to bepermanent records, writing in ball-point pen, Indian ink or spirit ink

177

will safeguard against accidental wetting. Pencil will not run on wetcard but is likely to smudge with handling.

It has been found that noise may impede breeding procedurespresumably by disturbing the does' oestrus cycles. The mothersdisturbed in this way are likely to eat their litters and adults arefrequently found to become vicious giving painful bites to thehandler and to prying fingers. Should mice become vicious only oneor two people should handle them, giving them time to become awareof their presence. All movements made near the mice when cleaningthem should be slow and gentle so as not to disturb them.

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CleaningMice urinate and defaecate during exercise and especially when

eating and drinking. They are extremely clean around the nestingarea. In the 'Cambridge' cage, the soiled bedding can be scooped outwithout disturbing the nest. If the mice are very active, a meshshield, shaped to fit the nesting corner, can be held over themduring cleaning. With particularly lively animals, the cage can be putin a large cardboard box, a dry sink, an aquarium, or the equivalent.It is particularly desirable not to disarrange the nest when birth isimminent or during nursing.

If the cages are cleaned and additional bedding is added at leastonce a fortnight, the smell of mice should not be objectionable andthe animals will remain healthy. Mice fed on cheese tend to smellstrongly. Mouse food as described below contains all the necessaryingredients and does not need a supplement such as cheese.

A layer of peat on the cage floor to a depth of about 5 mm plusa handful of hay provides a suitable bedding. The hay can betwisted into a rough sort of nest and put in the nesting area, butthis is not necessary as the mice will construct a nest without human.help.

Sawdust may be used as an alternative to peat but it may becontaminated by wild mouse droppings and should therefore besterilised by autoclaving for at least an hour. Peat is more steriletha-i sawdust and also absorbs the smell more effectively. Check hayfor the presence of mites and if necessary sterilise it by autoclaving.

It is a wise procedure to wash the troughs and other parts of thecages with hot water (75°C) once every 4-6 weeks. If a detergent crdisinfectant (e.g. Cetavlon, TCP) is used, the cages must be thoroughlyrinsed-out afterwards. The trough and the rest of the parts canwithstand boiling water and may be sterilised in an autoclave at5-6.7 X 104 N rrr? (8-10 p.s.i.). This is only necessary should themice become diseased.

Strongly smelling cages need cleaning. In warm, unventilatedconditions the cages will need cleaning more frequently than in coolwell ventilated conditions.

Feeding

Rat cake pellets obtainable from many pet stores make a goodfood. When placed on the cage cover they do not becomecontaminated with droppings and approximately 1-1.5 kg can beput there at a time. This will last about a fortnight with a maximum

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cage population. Use a smaller quantity if there are not many micein a cage so as to prevent the uncovered pellets becoming stale byprolonged exposure to the air. Other recommended foods areOxide 41B diet which is available in small quantities and Mousediet F available from E. Dixon Ltd. in 25 kg (~ hundredweight)sacks.

The water bottles have a single-holed bung through which is apiece of glass tubing (5 mm internal diameter) whose open end hasbeen heated until it has only a small hole (1 mm) in it. Capillarytubing 1.25-2 mm internal diameter and 6-8 mm external diameter,can be used but tends to become airlocked. The tubing protrudesfrom the bung about 15 mm and needs to be about 30 mm long,depending on the depth of the bung. The bottle is placed with thespout protruding through the hole below the two short horizontalbars, in the space left for it by the upright divider. It will then be atthe correct angle and distance from the cage floor. The bottle isfilled with water to within 25 mm of the top and the bung is pressedin tightly. The bottle is inserted gently into the cage so as not toshake any water into it. The water should be replenished when theinner projection of the tube is out of the water. A supply usuallylasts for a week.

Mice rarely flood the cage by building up their bedding againstthe water tube but they may do so if there is too much bedding. Aroutine daily check should be made that flooding has not occurredand that there is sufficient water in the bottles. Algae grow in thebottles if they are in sunlight. Such bottles should be emptied andsterilised by filling with a 10% solution of sodium hypochlorite fora few hours. They need to be rinsed well, refilled with water andreplaced in the cages.

HandlingMice should be picked up by the tail held half way along. They

will stay still if allowed to hold a coat sleeve or the bars of the cagewith their front feet. They quickly become accustomed to handlingproviding this is carried out gently. A doe which is used to beinghandled is less likely to desert her litter when that is handled, thanis one which is not used to such treatment. Up to 12 days old thewhole litter may be held in the hand and each mouse should bereturned to the rest of the litter as soon as possible after examination.Does are likely to reject cold young. Sometimes a litter born in newsurroundings is abandoned but it is usual that subsequent litters arewell cared for.

180

When mice are first received from suppliers they may find theirnew environment unsettling. Occasional handling at first with agradual increase in frequency will help them settle in two or threeweeks.

Young mice become very lively at 2-3 weeks of age and aredifficult to catch because they move so fast. After 5-6 weeks theyslow down and become more amenable to handling.

BreedingMice become sexually mature when they are 6-8 weeks old.

Gestation takes 19-21 days and longer if the doe is suckling. Theminimum generation is 9-10 weeks. The regular oestrus cycle is4-5 days and the doe will only accept a male every fourth or fifthnight. Mating can be detected by the presence of a vaginal plugformed by the male after copulation. It is a hard white substancewhich completely fills the vagina so that it can be seen with thenaked eye. When it is more deeply placed it can be detected with theaid of a small spatula gently inserted into the vagina. For exacttiming an inspection for vaginal plugs should be carried out daily.The plug usually disperses after 24 hours but may sometimespersist for 2-3 days.

Does may have eight or more litters in their lifetime. The firstlitter tends to be small but subsequent litters average out at aboutsix. The second and third litters are likely to be the largest with upto eleven or twelve young.

The young may be weaned at about twenty days old.

Sexing

Iteats of mammary-- L-_I 9',nd, \: . . . I

) V~-~\-·--9'n;"'p,p;", ) \

Yf" ..-·T""-i 'n"~'n;'"",p;n,._ .. j1~.-;'~\ / \ "I ~

/ '\ 0, f ~V Lmale adult female adult

181

Sexing is easiest from 0-15 days and after 6 weeks. The penis ofthe male is further from the anus than is the vulva of the female. Atabout one week the does show milk teats. Cases of mistaken identitydo occur and some mice may have genital abnormalities which giverise to incorrect sexing. It is best for breeding purposes to kill anyabnormal mice at an early age.

Social effectsMice are social animals. They react to each other in many subtle,

as well as obvious, ways. The oestrus cycle is modified differently bythe presence of males and by the presence of females. The cycle isshorter when males (or their smell) are present, but in the presenceof females only the cycle is mutually suppressed.

The presence of a different male after removal of a doe from themale with which she has mated can cause a failure of pregnancy,especially if the second male belongs to a different strain from thefirst. All litters born to females which have mated twice, withdifferent males, have been found to be sired by the second male.

Marking, killing and preserving mice

It is necessary to mark mice and this is best done by using stainsof different colours which dye the fur. Some stains are notpermanent and may have to be renewed from time to time, otherswill grow out as the hair is moulted. Vegetable dyes or hair dyes,obtainable from the local pharmacy are recommended.

Mice are killed, either by etherisation or by use oftrichloromethane (chloroform) in a closed airtight box. The killingbox should have a separate compartment for the killing liquid, whicfmust not come into contact with the animals. The vapour escapesfrom this compartment into the main part of the box, where themice are placed. A wad of cotton wood dampened with thekilling liquid is placed in the compartment.

If mice are to be preserved the easiest method is to skin themwhen freshly killed and to mount the skins on hardboard or woodenformers. Skinning is carried out by slitting the ventral surface fromhind leg to hind leg and peeling off the skin forewards, cutting attail tip, paws, ears and nose. Rub salt and borax into the skin thenstretch it on a former made to the size of the mouse. The former

182

needs an extension at the posterior end on which details of themouse are noted. Allow the skin to dry on the former and store withmothballs (naphthalene).

Mice intended for dissection may be dropped into 70% ethanolproviding the abdominal wall is first cut open to allow thepreservative to bathe the gut and other abdominal organs.

OnionOnion is suggested for examination in Investigations 5.1 and

6~ 6.l2.The best cells to show plasmolysis are large thin cells having a

coloured cell sap. Such cells are found in red onions and rhubarbstems. The red-skinned onion is recommended but may be difficultto obtain. The onions are available late in the year from the bettergreengrocers. They can be stored in a cool, dry place, individuallywrapped in newspaper. If ground is available they can be grownfrom seed obtained from seed merchants. For large onions sow in agreenhouse (or in a propagator - see Appendix 1) in the autumn andplant out the seedlings in April.

In rhubarb the area to obtain cells is from young stems whereskin is turning red on the flat inner side of the stem. In onions therequired tissue is the the thin skin on the inner side of the bulb'sfleshy leaves ..The method of obtaining this tissue is illustrated inthe diagram.

183

cut bulb in half break off fleshy leaf

~.---

lift off thin layer of cells break leaf

Standing the bulb in water overnight prior to the investigationwill cause the required tissue to be easily removed from the bulk ofthe bulb.

Paramecium

Paramecium is suggested for Investigation 4.1 and as an optionalalternative forA3.7b.

The culture medium for this organism is a hay infusion - seeAppendix 2. An alternative medium is prepared as follows:-1. Boil 6 wheat grains in 100 crrr' of pond or aquarium water (orwater culture solution - see Appendix 3) in a conical flask for3 minutes.

2. Allow to cool and plug with non-absorbent cotton wool.3. Leave to stand for 48 hours.

4. Inoculate with S crrr' of Paramecium culture.

S. Subculture as required, and adjust the pH to ',.2 by adding calciumcarbonate as necessary.

A large number of individuals may be obtained in a small volumeof culture by centrifuging and then drawing the Paramecia from thebottom of the centrifuge tubes with a fine ended dropper pipette.

Paramecia move quickly when observed under a microscope. Theymay be slowed in their motion by refrigeration or by the addition ofmethyl cellulose (e.g. Polycell) to the slide or with strands of cottonwool. The methyl cellulose is recommended and is made up byadding 1 g of the solid to 10 ern" of water. After soaking for 30minutes a further 12 crrr' of cold water are added and the gel

184

formed is stirred until smooth. Alternative methods are to exposethe culture for 5 minutes at a distance of 50 mm from a 6 W TUV(ultraviolet) lamp, or to add a drop of cool (but not solid) clearagar to the Paramecium on the slide.

Rat - dissection1. Pin the rat on its back on a dissecting board with four strongdissecting pins or nails through the feet.2. Using forceps and scissors cut through the skin of the abdomenand continue this cut forward to the throat and backwards to theanus. Cut around the penis on either side and continue the cutthrough the skin of the scrotum in the case of a male. Cut round theuro-genital aperture of the female and continue to the anus .

. 3. Pin back the skin with more dissecting pins.4. Cut open the abdominal cavity using scissors and forceps and pinback the flaps of muscle as shown in the diagram. When cuttingforwards go only so far as the rib cage. When cutting backwardstake care not to puncture the bladder.

5. Rearrange the gut carefully using the fingers. Adhesions of themesenteries can be relieved with a little water which will helpprevent them tearing.

abdominalwall-------'-~pinnedback

_----f:.~~~~T-\--t_--caecum__ --!'---_-+---,-;~"'!-- -,,r-:-~--';----+___-- fat body

rat,dissectedto showabdominalorgansin situ

185

Serratia marcescens

Serratia marcescens is suggested for Investigation c-l.I O.This is a non-pathenogenic (not disease causing) bacterium which

produces easily visible colonies when grown on agar. The experimentis concerned with the effect of the environment on the growth oforganisms, and the bacteria are grown on two different types ofagar to demonstrate the environmental effect.

The stock cultures of Serratia marcescens will probably begrowing on an agar slope in a McCartney bottle when obtained fromthe supplier, and the colonies will probably have a white, translucentappearance. If stored and grown at a low temperature the coloniesmay have a pink tinge. Normally colonies grown on nutrient agar -(see Appendix 2 'Agars and broths') - at 37°C have no red pigment,but if grown at this temperature on glycerol nutrient agar, redcolonies are formed.

An extension to the experiment requires red colonies to besub-cultured onto nutrient agar plates and white colonies to besub-cultured onto glycerol agar plates. For full details concerningthe production of agars, making streak plates, and sterilisationprocedures see Appendix 2 'Agars and broths'.

Tribolium species

Tribolium, the flour beetle, is a convenient organism which maybe preferred to Drosophila for breeding experiments. It is suggestedfor Investigation e 3.7b and 3.8. Culture methods are easily appliedbut sexing is difficult.

The two species suggested are T. castaneum and T. confusum.These species are readily distinguished with a little practice, and thewild types only are required for this part of the course.

Diagnostic featuresT. castaneumAntennae with distinctthree-segment club

Red/brown colour

Head without ridge above eyes3-6 mm long

186 A = 1.75 Bdiagnostic features of T. cesteneum and T. confusum

A=3B

T. confusumAntennae without club or withindistinct five-segment club

Dark brown colour

Head with ridge above eyes4-4.s mm long

Culture methodThe culture medium consists of 19 parts of wholemeal flour to

one part of powdered dried yeast. No water is necessary since thebeetles obtain their requirements from their food.

Containers are SOOg Kilner type jars in which the glass lid hasbeen substituted by filter paper or a perforated polythene sheet.The culture is best kept at 3SoC over a tray of water to maintainhumidity. The culture is divided when the beetle population becomeshigh.

HandlingTo obtain adult beetles put a screw of paper in the culture

container and leave overnight. Many beetles will crawl into thecrevices.

Remove the paper and unravel it over a tray. Pooters (see diagrambelow) should not be used to remove beetles from the containerbecause of the dusty medium, but can be used to pick up adults fromthe tray.

An alternative method is to sieve the medium using a flour sieve,wire mesh tea strainer, or any sieve with holes approximately1 mm X I mm. In this way adults, pupae and larvae can be collected.Eggs are so small that they remain in the flour or adhere to the meshof the sieve, so a different sieve should be used for each culture toavoid cross contamination. For the same reason the cultures shouldbe sieved well away from each other.

I---------snp.r.imen tube150mmx25mm

pooter

187

Life cycle

The adult beetles mate soon after emergence from pupae andstore sperm for some time, so if breeding experiments are to beundertaken the sexes should be separated at the pupal stage. Femaleslay eggs about ten days after emerging from pupae and continuelaying for a couple of months. Eggs hatch after about four days andstart a larval period of about three weeks. The larvae then pupatefor about one week before emerging as adult beetles. Times will varyconsiderably according to temperature and humidity.

SexingAdult beetles are very difficult to sex even for the experienced

handler. It is useful to sex pupae.In the male pupa the external genitalia are two short appendages

which are little more than rounded protuberances, whereas in thefemale the appendages are divergent, segmented and altogether moreprominent.

QFemale MalecJ'

Ventral surface of the abdomen of Tribolium pupae

A stereo microscope giving X40 magnification is desirable forthis method of sexing.

In the adult stage sexing relies on the differences in the groovesand ridges at the apex of the elytra. In the male these arediscontinuous, whereas in the female all but the extreme outsideones are continuous.

\QFemale MalecJ'

188

Unfortunately when viewed by normal top illumination it isdifficult to see the ridges since they are on a curved surface. It isadvisable to use a combination of top and lateral lighting inconjunction with a X40 stereo microscope.

Sexing by probabilityWith the problems of sexing Tribolium beetles a method of

sexing by probability is suggested. Approximately equal numbers ofeach sex are produced when the beetles reproduce, so a sample often adults is likely to contain approximately equal numbers ofmales and females. In order to ensure that experiments aresuccessful, several tubes or jars are set up containing unsexed adultsand some of the jars will contain viable numbers of each sex.

For Investigation eL'Zb two or three jars are set up at the end ofthe summer term and further cultures are started at one weekintervals until they are needed. Each culture should be started with10-20 adult beetles.

Yeast cultureYeast is suggested as an alternative organism for Investigation

A3.7b.

Culture medium5 g Dried yeast

50 g Sucrose (sugar)1000 crrr' Water (distilled)

The sucrose is dissolved in the water in a sterilised flask and whendissolved the yeast is added to it. Shake well and incubate for twodays at room temperature in a flask plugged with non-absorbentcotton wool.

After one day make a count of the yeast (and at frequentintervals for several following days) as follows. Shake the flask wellto ensure an even distribution of the yeast throughout the culture.Take a small quantity of the culture on a pin head and place it on amicroslide, covering it with a 9 mm coverglass so as to spread theyeast thinly and evenly. View the slide with a microprojector ormicroscope fitted with a high-power objecqve and count the numberof cells in the field of vision. Repeat for further samples from other

-areas of the slide.Addition of meth lene blue stain to the sample will enable the

cells to be seen more clearly.

189

Appendix 3 Chemical preparations

For common reagents, solutions are made by diluting stocksolutions. This appendix gives both instructions for diluting to therequired strength from stock solutions and also instructions forpreparing the more dilute solutions from solids and concentratedreagents. In all cases there is no need to take quantities accurately,they are intended to be guides to the order of concentration: thus a1.1 M solution will be as satisfactory as a 0.9 M solution and both ofthese can be used where a 1.0 M solution is required.

Most of the recipes given here produce molar solutions ratherthan percentage solutions. Where percentage solutions are giventhey are prepared according to the following convention:

Solutions whose components are liquid

These are v/v (volume/volume) solutions in which the combinedvolume of the liquid components is 100 ern> or a multiple orsub-multiple of this volume in which the relative proportions of thecomponents is the same as if the total volume were 100 ern>.

Solutions of solids in liquids

These are m/v (mass/volume) solutions in which the required massof solid is dissolved in solvent and the total volume is made up to100 em"; or a multiple or submultiple of this volume in which therelative proportions of the components is the same as if the totalvolume were 100 ern? .

Where appropriate, solutions are cross-referenced against theinvestigation numbers where they are used, or against appropriateappendix references.

Ammonium hydroxide, !4 strength

This solution is used in Investigation 6.1 c.Dilute 125 cm ' of concentrated (0.880 sg.) ammonia solution to

500 ern> with water.

190

Ammonium hydroxide, 5 M

This solution may be regarded as the stock solution. It is used inInvestigation 7.21.

Dilute 335 ern> of concentrated (0.880 s.g.) ammonia solution to1000 em> with water.

A mmonium hydroxide, 2 MThis solution is used in Investigation 6.1 c.

Dilute 1000 crrr' of 5 M ammonia to 2500 crrr' with water.Or: Dilute 350 em" of concentrated (0.880 s.g.) ammonia solutionto 2500 ern" with water.

Ammonium sulphate, 0.09 MThis solution is used in Investigationc a 8.20.

Dissolve 12 g of solid in water and make up to 1000 em" ofsolution

Barium chloride, 0.5 MThis solution is used in Investigation 8.19.

Dissolve 122 g of solid (BaC 12 .2H20) in distilled water and makeup to 1000 crrr' of solution.

Benedict's solution

This solution is used in Investigation. 6.20.The solution may be bought ready made: or, make the solution asfollows:

100 g173 g

800 crrr'

Sodium carbonate Na2C03 .1OH20Sodium citrate Na3C6 Hs 07 .2H20Water, distilled or de-ionised

Dissolve the solids in distilled water and filter if necessary.Dissolve 17.3 g of copper (II) sulphate (CUS04 .5H20) in thecarbonate/citrate solution and make up to 1000 crrr' with distilled

. water. Filter the final solution if it appears cloudy.

191

Cobalt chloride paperThis paper is used in Investigation 6.26.The paper can be bought, or made by soaking filter paper in a

saturated solution of cobalt chloride.The salt is highly deliquescent and very little water need be

added to make a strong solution.Dry the paper in an oven set at 100°C. It will turn blue when the

water of crystallisation has been driven off. The blue paper shouldbe kept in a desiccator.

Copper (II) chloride, 0.5 M

Dissolve 85 g of copper (II) chloride (CuC12 .2H20) in 800 em>of distilled water and make up the volume to 1000 ern-of solutionwith distilled water.

Copper (II) chromateCopper (II) chromate may be purchased as a solid which is

insoluble in water. In Investigation.8.9 the solid is dissolved in aminimum volume of 2 M hydrochloric acid - see Appendix 3 - toproduce a saturated solution and then as much urea as possible isdissolved in the solution.

Copper (II) sulphate, anhydrousThis substance is required in Investigation 6.26.Small quantities are easily produced by heating the hydrated salt

gently over a Bunsen burner flame in a crucible or evaporating basin.Large quantities are best dried in advance of their being required inan oven set at 120°C.

It is advisable to keep anhydrous substances in a desiccator or afrequently used incubator so that they are always to hand in aprepared state.

Copper (II) sulphate, 0.5 M

This solution is required for Investigation 2.6Dissolve 125 g of the solid (CUS04 .5H20) in distilled or de-ionised

water. Add 3 cm-' of concentrated sulphuric acid, taking care lest itshould splash up. Make up the volume of solution to 1000 cm-' withdistilled water.

192

Copper (II) sulphate, 0.25 MThis solution is required for Investigationo 6.11a.Dilute 500 em> of 0.5 M copper (II) sulphate solution to 1000

em> with distilled or de-ionised water.Or: Dissolve 62.5 g of the solid (CUS04 .5H20) in distilled water.

Add a few drops of concentrated sulphuric acid and dilute thesolution to 1000 ern> with distilled water.

Copper (II) sulphate, 0.05 MThis solution is required for Investigation 8.11Dilute 100 crrr' of 0.5 M copper (II) sulphate solution to

1000 crrr' with distilled or de-ionised water.Or: Dissolve 12.5 g of the solid (CUS04 .5H20) in distilled water.

Add a few drops of concentrated sulphuric acid and dilute thesolution to 1000 cnr' with distilled water.

Copper (II) sulphate, 0.04 M

This solution is required for Investigation .47.22.Dilute 80 em" of 0.5 M copper (II) sulphate to 1000 crrr' of

solution with distilled or de-ionised water.Or: Dissolve 109 of solid (CUS04 .5H20) in distilled water. Add a

few drops of concentrated sulphuric acid and make up the volume ofthe solution to 1000 ern- with distilled water.

Hydrochloric acid,S MThis solution may be regarded as the stock solution. It is used in

Investigations 1.1 ,.41.4,.42.7 ~7.3, 8.16b, and 8.19.Carefully pour 437·5 em> of concentrated acid into 500 ern> of

cold water. Add the acid slowly and with stirring. Allow to cool.Make up the volume to 1000 em" with cold water.

Hydrochloric acid, 2MThis solution is used for Investigations 2.4 and.4 8.9.Dilute 400 em> of 5 M hydrochloric acid to 1000 cm-' with cold

water.Or: Carefully pour 175 ern" of concentrated acid into 500 cm-'

of cold water. Add the acid slowly and with stirring. Allow to cool.Make up the volume to 1000 ern? with cold water.CAUTIQ~·:·FIy~tPCl1:l

193

Hydrochloric acid, 1MThis solution is used in Investigationo 6.13.Dilute 200 em> of 5 M hydrochloric acid to 1000 ern- with cold

water.Or: Carefully pour 87·5cm3 of concentrated acid into 500 em- of

cold water. Add the acid slowly and with stirring. Make up thevolume to 1000 ern> with cold water.

Hydrogen peroxide, 20 vol.This solution is required for Investigation 2.11.The solution may be bought as a 20 vol. solution or the solution

may be made by diluting 200 em> of 100 vol. solution to 1000 em>with water.

Solutions are unstable and should be stored in dark glass bottlesfitted with a rubber bung with a valve. The bottles should be kept ina cool place. The solutions are supplied in suitable containers.

These strong solutions should be handled carefully as they arestrongly oxidizing and will attack skin and clothing.

Iodine in potassium iodide solution (I2/KI), 3%This solution is usually dispensed in small dropper bottles. It is

required for Investigations 5.1 , 6.19. and. 6.20.The reagent may be bought ready prepared or may be made as

folIows:-Dissolve 30 g of resublimed iodine and 150 g of potassium iodide

in 800 em" of distilled water. The mixture needs to be shaken well todissolve the solids. When the solid has dissolved make up the volumeto 1000 em> with distilled water.

Lead acetate, 0.1-0.5 MThis solution is required for Investigation 7.7 a.Dissolve between 38 g and 190 g in distilled water and make up

the volume of the solution to 1000 em> with distilled water.Tap water will cause a cloudy suspension to form.

Lime waterLime water is required for gas tests in Investigations 1.1,.1.2,

.1.4, 6.1a and.8.7. Dispense the solution in dropper bottles.Prepare the solution by standing water over calcium hydroxide

(slaked lime) in a Winchester bottle and shaking it. Allow to settle

194

and filter as required. From time to time the stock bottle should beshaken and more water and fresh solid added occasionally.

Litmus indicator, 0.1%This indicator is suggested for use in Investigation 8.l6b.The solution may be bought ready made or may be prepared as

follows:-Dissolve 1 g of azolitmin in 1000 cm-' of distilled or de-ionised

water. The solution may be warmed to help the solid dissolve.Filter off any undissolved solid.

Methylene blue, 1% aqueousThis stain is used in Investigations .3.7b and 5.1 .Dissolve 1 g of methylene blue and 0.6 g of sodium chloride in

100 ern" of distilled or de-ionised water.

Millon's reagentThis reagent is easiest bought in a small quantity as a combined

solution. It is required for Investigation. 7.22.The reagent may be prepared as follows:-For solution A:

100 g Mercury (II) sulphate100 crrr' Concentrated sulphuric acid

1000 crrr' Distilled waterCarefully pour the sulphuric acid into 800 crrr' of the water.Grind the mercury (II) sulphate in a mortar and pestle with

successive portions of the acid, pouring off the clear supernatantsolution into a 1000 em" volumetric flask. When all the mercury (II)sulphate is dissolved, dilute the solution to 1000 cnr' with distilledwater.

For solution B:Dissolve 5 g of sodium nitrite (NaN02) in 500 crrr' of distilled

water.Before use mix two parts by volume of solution A with one part

of B. The combined solutions may be kept for some time in a darkbottle in a cool place.

Nitric acid, 60%This solution is suggested for cleaning apparatus in Appendix 1.

Pour 60 cnr' of concentrated nitric acid slowly and carefully into40 crrr' of cold water.

195

Nitric acid, 5MThis solution may be regarded as the stock solution. It is used

in Investigations 1.1, A7.3, and 8.19.Pour 222 crrr' of concentrated nitric acid slowly and carefully

into 500 crrr' of cold water. As the acid is added to the water stircontinuously. Allow the solution to cool and then dilute to1000 ern" with cold water.

Potassium hydroxide, 1MThis solution is required for Investigation A 7.22Dissolve 62.5 g of (90%) pellets or 56 g of pure pellets in

800 crrr' of cold water, with constant stirring to prevent localisedheating and possible breaking of the container. After cooling thevolume is made up to 1000 crrr' with cold water. The pellets usedshould not be dull nor contain powder (potassium carbonate). Thesolution may be made safely in polythene beakers, buckets or othercontainers.

Solutions of potassium hydroxide should be kept in bottlesfitted with rubber bungs NOT ground glass stoppers, which maybecome cemented into the necks due to the formation of potassiumcarbonate.

Silver nitrate, 0.5 M

This reagent is required for Investigation 2.6.Dissolve 85 g of solid in distilled water to give 1000 em> of

solution. Tap water will cause a cloudy suspension of silver chloride.

Silver nitrate, 0.1 M

This solution is used in Investigations 6.19, 7.7b, A8.7c and 8.19.Dissolve 17 g of solid in distilled water to make 1000 em> of

solution. Do not use tap water as this will produce a cloudysuspension of silver chloride.

'Soap' solution

The soap solution is required for Investigation ~ 6.3.Mix together 1 cm ' Teepol (detergent), 8 em> glycerol, and

32 em> distilled water.

196

Sodium chloride, 0.5 MThis solution is required for Investigation 2.6.Dissolve 29 g of solid in water to make 1000 cm' of solution.

Sodium chloride, 0.1 MThis solution is required for Investigations 6.19 and •.6.20.Dilute 200 em> of 0.5 M sodium chloride solution with water to

make 1000 cm-' of solution.Or: Dissolve 5.85 g of solid to make 1000 em> of solution.

Sodium hydroxide, 5MThis solution may be regarded as the stock solution. It is used in

Investigation 8 .16b.Dissolve 220 g of (90%) pellets in 800 ern" of cold water, with

constant stirring to prevent localised heating and possible breakingof the container. After cooling the volume is made up to 1000 cm-'with cold water. The pellets used should not be dull nor containpowder (sodium carbonate). The solution may be made safely inpolythene beakers, buckets or other containers.

Solutions of sodium hydroxide should be kept in bottles fittedwith rubber bungs NOT ground glass stoppers, which may becomecemented into the necks due to the formation of sodium carbonate.

This solution is used for adjusting the pH of culture media.Dilute 200 ern" of 5 M sodium hydroxide to 1000 em" of

water.Or: Dissolve 44 g of (90%) pellets in 1000 cm 3 of water.

Sodium silicate, 2MThis solution is required for Investigation c 6.11b.Dissolve 240 g of sodium silicate powder (Na2 Si03) in

distilled water andmake up the volume to 1000 em".Or: Dissolve 425 g of sodium metasilicate (Na2 Si03 .5H2 0) in

distilled water and make up the volume to 1000 ern>.

Starch solution, 1%This solution is required for Investigation 6.19, and •. 6.20.Mix 109 of analytical grade starch with a little distilled water to

make a thin paste:. Make up the volume to 1000 ern- with boilingdistilled water and simmer the mixture while stirring until a clearsolution is obtained.

197

The solution may be stabilised by adding lag of potassiumiodide and 5 ern" of trichloromethane (chloroform)

Sucrose, 75%This solution is required for Investigationc 6.13.Dissolve 750 g in water and make the volume up to 1000 ern>.

Sucrose, 50%This solution is required for Investigations i':.6.11 c,i':. A 6.12 and

A6.13.Dissolve 500 g in water and make up the volume to 1000 ern" .

Sucrose, 5%This solution is required for topping up yeast cultures.Dissolve 5 g of sucrose in 95 em" of distilled water.

Sulphuric acid, 2.5 M

This may be regarded as the stock solution. It is used inInvestigations •. 1.2, Al.4, A7.3 and 8.16c.

Carefully and slowly pour 140 ern> of concentrated sulphuricacid into 500 em> of cold distilled water. Stir continuously as theacid is added and take care that it does not splash upwards. Aftercooling make up the volume to 1000 ern> with water. Work with thevessel in a sink and do not lean over it while mixing.

Sulphuric acid, 1 MThis solution is used for Investigations 2.11 and 8.16a.Dilute 400 ern" of 2.5 M sulphuric acid with cold water to make

1000 ern? of solution.Or: Carefully and slowly pour 56 ern> of concentrated sulphuric

acid into 500 em> of cold water. Stir continuously as the acid isadded and take care that it does not splash upwards. After coolingmake up the volume to 1000 em> with cold water.

WaterDe-ionised (DI) water can be substituted for distilled water for

school uses. The only time distilled water has any advantage over DIwater is when pH indicator and culture solutions are being prepared.On standing both types of pure water will dissolve carbon dioxide(and, in industrial areas, sulphur oxides) from the air. Freshly

198

distilled water will tend to have negligible quantities of these acidicgases (and other gases) present. In any case indicator solutions shouldbe made using freshly boiled water. (NB pure water is only neutralat 22°C and at standard pressure of one atmosphere (10s N rrr+).

It is a false economy to use tap water rather than distilled orde-ionised water, and the following cases do require the purifiedwater:-1. Solutions of indicators and stains, and culture solutions.2. Solutions required for accurate analytical work.

3. Solutions made from substances likely to react with saltsdissolved in tap water.

4. Test reagents.The substances listed below should always be dissolved in

distilled water, otherwise they are unlikely to be of theconcentration required (relevant to analytical work). If made upwith tap water they will need to be filtered to remove precipitatesformed.Ammonium oxalate (tests for Ca2 + ions)Barium chloride (tests for S032 - and S042 - ions)Barium hydroxide

Lead acetate

Silver nitrate (tests for CI- ions)

Silver sulphate

Water culture solutionsThese solutions are specifically mentioned in Investigation 8.19.In general, pond water which has been well boiled and then

filtered should be used rather than water culture solutions, exceptwhere the effect of different ions on the growth of plants andanimals is to be investigated. The great advantage of pond water isthat it contains the trace ions such as manganese which are notincluded in the solutions described and also that it tends to havethe correct ion balance for organisms which have been collectedfrom it.

The optional extension work to 8.19 entails an experimentinvestigating the effects of ions on the growth of Lemna.Griffin &. George Ltd produce a Plant Culture Kit which satisfiesthe needs of this and similar experiments.

199

Appendix 4 Hazards andprecautions

Chemical hazards

Ammonia, 0.880 s.g. (Ammonium hydroxide).

Poisonous and corrosive solution giving off an irritant chokingvapour.

Lungs Remove patient from exposure. Rest and keep warm. If severelyexposed

Obtain medical attention

Skin Wash well with water. If severely affected


Mouth Wash out well with water. Give vinegar or 1% acetic acid to drink.


Eyes Irrigate eyes with water by placing head under a running tap. Ifdirect contact has occurred (i.e. by splashing)


Barium chloridePoison.

Mouth Wash out mouth thoroughly with water. Give 2 tablespoonfuls ofmagnesium sulphate (MgS04 .7H2 0 - Epsom salts) in waterfollowed by an emetic; such as 1 tablespoon of mustard in ~ glassof cold water, or 1 tablespoon of common salt (sodium chloride)in warm water; then


200

BromineBoth liquid and gas of this element are very volatile. Causes severeburns if spilt on skin and prompt first aid treatment is veryimportant. The vapour is particularly corrosive to the eyes andrespiratory system. Bromine is also a fire hazard and can inflameorganic materials including sawdust.Wear rubber gloves when using bromine and work in a fumecupboard.

Lungs Remove patient from exposure. Rest and keep warm. If severelyexposed


Skin Drench affected area with water and remove any contaminatedclothing. Bathe with a dilute solution of sodium thiosulphate (hypo).


Mouth Wash out mouth thoroughly and give large quantities of water todrink.


Eyes Irrigate eyes thoroughly, then


Carbon tetrachloridesee Tetrachloromethane

Chloroformsee Trichloromethane

Ethoxyethane, (Ether, Diethyl ether)

Highly inflammable. Anaesthetic. May form explosive peroxides ifstored for long periods and exposed to light. Use in a fume cupboardor well ventilated room.No naked flames in the room when ether is in use.

201

Lungs Remove patient from exposure. Rest and keep warm. If exposure issevere


Hydrochloric acidVery corrosive. Gives off irritant vapour. Use in a fume cupboard.

Lungs Remove from exposure. Rest and keep warm. If exposure is severe


Skin Wash well with plenty of water. In severe cases


Mouth Wash out mouth with plenty of water. Give plenty of water todrink, then give milk of magnesia and


Eyes Irrigate eyes with water by placing head under a running tap. Ifdirect contact has occurred (i.e. by splashing)


IodinePoisonous volatile substance. Vapour irritates eyes and respiratorysystem.

Lungs Remove patient from exposure. Rest and keep warm.

Skin Drench with water, then bathe with a dilute solution of sodiumthiosulphate (hypo).

Lead (II) bromide

Poisonous. Gives off bromine vapour when heated - brominehazard also.

202

Lead saltsPoisonous

Mouth Wash out with water. Give 2 tablespoonfuls of magnesium sulphate(MgS04 .7H2 0, Epsom salts) in water. Give an emetic - seeAppendix 4 'Barium chloride'. Rest and keep warm.


LycopodiumLycopodium powder is very fine and could cause an explosion ifignited while suspended in air.Some children and adults are allergic to Lycopodium powder.Sufferers from hay fever are likely to notice the effects of thepowder in the air. An alternative powder for most purposes is talc.

Magnesium

Magnesium powderin particular constitutes a dangerous fire hazard.Dry sand is the only means of extinguishing a magnesium fire. Useof a water or tetra chloromethane (carbon tetrachloride) fireextinguisher will lead to an explosion.

MercuryExtremely poisonous vapour.In all cases of suspected mercury poisoning


Spillages of mercury should be cleaned up immediately. If thespillage is in an inaccessible place it should be treated so as to renderit harmless. It is advisable to wear rubber gloves when handlingmercury and if gloves are not available all cuts and abrasions on thehands should be well covered. Personal jewellery (rings etc) shouldbe removed before handling mercury since the gold will readily forman amalgam and turn 'silver'. The amalgam is unstable and as itdecomposes the mercury released is likely to be absorbed by the skin.When spillages occur a proprietary collecting instrument (such asthe mercury collecting pad from GG, or the E-mil suction mercuryretriever) may be used to pick up the mercury, or small globules

203

may be pushed together by means of the edge of a card and bepicked up using a plastic hypodermic syringe as a suction pump. Ifthe mercury has run into inaccessible cracks, for instance betweenfloorboards, pour zinc dust or sulphur flowers to form thenon-volatile zinc amalgam or mercury (II) sulphide. Both substancestake time to react completely. The sulphur technique requiresseveral weeks before any attempt is made to clean out the crack.If mercury has become chemically contaminated the safest methodof decontamination is to send it to Belgrave (Mercury) Ltd who willredistill it at reasonable cost.Surface-dirty mercury is easiest cleaned by use of Fison's mercurycleaner which produces clean, dry mercury by simply pouring themetal through the cleaner over a collecting vessel.

Mercury (II) sulphate and

Millon's reagentThis reagent contains mercury salts.If mercury poisoning is suspected give plenty of milk to drink, and


Nitric acid

Very corrosive. Gives off irritant vapour (dinitrogen tetroxide) inmany reactions.





Mouth Wash out mouth with plenty of water. Give plenty of water todrink, then give milk of magnesia and


204

Potassium hydroxide and

Sodium hydroxideVery corrosive as solid or solution. Generates heat when dissolving.Wear protective gloves when using.

Skin Wash affected area with plenty of water, then bathe with vinegaror 1% acetic acid.

Eyes Irrigate thoroughly with water and


Sulphuric acid

Very corrosive. Reacts violently with water. When diluting, theconcentrated acid must be poured slowly and carefully withstirring into a large volume of cold water. Do not lean over thevessel while mixing.



Mouth Wash out with water. Give plenty of water to drink, then give milkof magnesia and


Eyes Irrigate well with water and


Tetrachloromethane, (Carbon tetrachloride)

Poisonous. Continuous exposure to low concentrations may giverise to irreversible liver damage. Use in a fume cupboard.



205

Skin Drench skin with water, then wash with soap and water. Air clothesbefore re-use.

Trichloromethane, (Chloroform)

Has a narcotic effect, can cause hallucinations and unconsciousness.The poisonous gas phosgene may be present.Use in well-ventilated conditions.

Electrical hazards

Electrical supplies are classified into low tension (1.t.) under 100 V,high tension (h.t.) 100-500 V and extra high tension (e.h.t.) overSOOV.

Van de Graaff generatorThe Van de Graaff generator is capable of producing extremely highvoltages. On a dry, cold day it can produce a voltage well in excessof 3 X 104 V, providing all surfaces are clean and dust free.Generally this equipment is reasonably safe as the current itproduces is at the microamp level (pA) , but some people (e.g. thosewith weak hearts) are susceptible to these voltages. All electricalequipment should be used with great care. Discharging tongs areavailable from reputable manufacturers of static electricitygenerators and it is advisable to discharge the generator spheresbefore making any alterations to the circuit. It is advisable to earththe chassis of the generator to a metal pipe (but not a gas pipe).Electrically driven generators are usually supplied with a threecored lead in which the earth lead (green and yellow) makes thisconnection to earth without the need for a special arrangement.

E.h.t. supplies

The rules regarding the Van de Graaff generator also apply here.However, as the supply is taken from the mains it is possible todraw a higher current than that usually produced in the generator.It is, therefore, essential, when purchasing e.h.t. power supplies, toensure there is a large current-limiting resistor in series with thepositive (+) terminal, fitted into the supply. Always connect thenegative socket to the earth socket unless otherwise instructed.

206

Gas cylinders

Carbon dioxide cylinders are usually painted black with, in somecases, a silver neck. The valve outlet has a right-hand screw thread.

Hydrogen cylinders are red, and the valve outlet has a left-handscrew thread which denotes an inflammable gas.

Nitrogen cylinders are grey with a black neck. The valve outlethas a right-hand screw thread.

Oxygen cylinders are black and the valve outlet has a right-handscrew thread. Medical oxygen cylinders are black with a whiteneck.

All cylinders should be labelled by the suppliers with the nameof whatever gas is in them. They should be checked on receipt of arecharged cylinder. If there is any doubt concerning the contents ofa cylinder it should not be accepted. It is a good plan to label eachcylinder with the date on which it was recharged. Check the gas fromtime to time, particularly before it is required, so that there istime to have the cylinder recharged if it is empty. The quantity ofgas in a carbon dioxide cylinder is checked by weighing the rechargedcylinder on arrival, and at intervals afterwards. The mass of containedgas and the tare mass (the mass of the empty cylinder) should bestamped on the cylinder. The quantity of gas in other cylinders isjudged from the reading of the cylinder contents gauge on theregulator.

Cylinders should be stored in a cool place away from radiators.They should be protected from rusting and from corrosiveconditions. Oxygen and hydrogen cylinders should not be stored, orused, near one another. If they are in the same room they should bekept far apart.

Store and use gas cylinders in an upright position, secured so thatthey cannot fall over. They must not be propped up against a wall.,nor left unsupported. Cylinder trolleys may be used for both storageand use.

Never use cylinders in an inverted position.Cylinders should be kept clean and free from grit, water, and

oil. This is particularly important for the cylinder valves, theregulator, and the key spanners. The key spanners should not beregarded as general purpose implements but kept for use with thecylinders.

The regulator, valves, keys and spanners must not be oiled orgreased. Oil and grease can ignite in the presence of oxygen and anexplosion could occur.

207

When returning cylinders to the supplier for recharging alwaysclose the main valve and remember to remove the regulator andspindle key. Keep the regulator in a clean, dry place. Collection,refilling and return of cylinders often exceeds a month, so plan wellin advance.

The diagrams below indicate the parts of typical cylinder heads.

- --- pressure gauge showspressure of gas in cylinder

spindle key ---

qas cylinder, - ~nitrogen or oxygen

I fine adjustment valve,right hand

outlet nut- -~and nipple,

left hand

--pressure gaugeshows pressureof gas incylinder

gas cylinder, hvdroqenv>

208

Hydrogen, nitrogen and oxygen cylinders

Fitting the regulator and checking for leaks:

1. Remove the plastic seal from the neck of the cylinder (wherefitted).

2. Close the regulator by screwing the handle out.

3. Check that there is not any dirt or grit in the regulator orcylinder valve socket.

4. Screw the regulator into the cylinder valve socket to be fingertight. Remember that it is a right-hand thread for nitrogen andoxygen, but a left-hand thread for hydrogen.S. Tighten the nut on the regulator with the regulator spanner.Other spanners should not be used, nor should devices be fitted tothe spanner to gain extra leverage. A firm but not forced fit isrequired.

6. Open the cylinder valve slowly with the spindle key, turning it inan anti-clockwise direction until it is fully open. This will cause areading to register on the cylinder contents gauge and indicate thecontents of the cylinder. The valve of a newly filled cylinder will bestiff and may open suddenly as force is applied.

7. Close the cylinder valve by turning the spindle key clockwiseuntil it is tight, but not forced. If there is a gas-tight fit between theregulator and the cylinder then the reading on the cylinder contentsgauge will remain constant for an hour or so. If the reading fallsthen there is a leak. In rare cases this could be caused by a faultyregulator, but it is most likely to be a poor seal between theregulator and the cylinder. In this case the regulator nut should beloosened, the regulator removed, and the connection checked fordirt or grit before refitting and tightening.

Using the cylinder:

1. Fit the regulator as described above. Fit the outlet nut and nippleto the regulator, tightening the nut with the hose spanner. If a fineadjustment valve is to be used, fit this to the regulator first and thenattach the outlet nut and nipple (right-hand thread for nitrogen andoxygen, left-hand thread for hydrogen).

2. Make sure that the regulator valve is closed, i.e. screwed out, andthat the fine adjustment valve (if fitted) is closed.

3. Open the cylinder valve slowly by turning the spindle keyanti-clockwise.

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4. Where no fine adjustment valve is fitted, slowly open theregulator valve by screwing in and the gas will flow. When using gascylinders for the first time be prepared for the hissing noise of thegas, which may be startling. Adjustment of the regulator valve givesthe required gas flow, and the working pressure is indicated on theappropriate gauge, or on the scale on the barrel of the regulatorvalve.

Where a fine adjustment valve is fitted, slowly open theregulator valve fully by screwing it in. Slowly open the fineadjustment valve and gas will flow with a hissing noise.Manipulation of the fine adjustment valve will give the required gasflow, and the working pressure will be indicated on the appropriategauge if fitted.

5. After use, close the fine adjustment valve, the regulator valve,and the main cylinder valve in that order. Open the fine adjustmentvalve and the regulator valve in order to relieve pressure on theregulator diaphragm. Finally close all valves.

Carbon dioxide cylinderThe recommended carbon dioxide cylinder for producing dry ice(solid carbon dioxide) is the siphon type and it is fitted with asimple valve. Pressure gauges are not fitted and pressure control isvery limited. The supplier's instructions should be followed. Thistype of cylinder is not suitable for supplying carbon dioxide gas. Asecond cylinder fitted with regulator and pressure gauges isrecommended for supplying carbon dioxide gas.

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Schools CouncilIntegrated Science Project (SCISP)

Patterns provides a structured coursein integrated science for pupils inthe 13-16 age range, aimed principallyat a double O-level. The scheme isoutlined in the Teachers' handbook andthe material is organised infour sections:Patterns 1 Building blocksPatterns 2 Interactions and building blocksPatterns 3 EnergyPatterns 4 Interactions and changeEach section comprises a pupils' manual,a teachers' guide, a technicians' manualand a number of pupils' topic books.

Longman Penguin ISB 0 582 34005 5

Documents

11351-Technicians Manual 1.pdf