4701 4705.output

* GB785108 (A)

Description: GB785108 (A) ? 1957-10-23

Manufacture of hexahydrobenzylamine

Description of GB785108 (A) Translate this text into Tooltip

[75][(1)__Select language] Translate this text into

The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

COMPLETE SPECIFICATION Manufacture of Hexahydrolienzylamine We, J. R. GEIGY A.-G., a body corporate organised according to the laws of Switzerland, of 215 Schwarzwaldallee, Basle, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The reduction of aromatic nitriles such as benzonitrile, tolunitrile and benzyl cyanide, in the presence of---acetic acid anhydride to form the corresponding acetylamino compounds is already known. The aromatic nude-us -is not affected in this reaction (J. Am. Chem.Soc. 47, 3051 (1925)). The reduction of 1 .4-dicyano-cyclohexane with platinum oxide in acetic acid anhydride to form the corresponding diamine is also known. In contrast to the above, it has now been found that tetrahydrobenzonitrile can be hydrogenated with hydrogenation catalysts in acetic acid anhydride while simultaneously saturating the double linkage to give good yields of hexahydrobenzylamine. Instead of the already known noble metal catalysts of the platinum oxide type, other hydrogenating catalysts from the eighth group of the periodic system can be used, such as finely distributed nickel or cobalt.

Advantageously the reaction is performed by dissolving tetrahydrobenzonitrile in a mixture of glacial acetic acid and acetic acid anhydride and, after the addition of the hydrogenation catalyst, the mixture is treated with hydrogen in a pressure resistant vessel while stirring at temperatures between 40 ad 100"C and at pressures between 20 and 300 atm. Suitable hydrogenating catalysts are finely distributed nickel, cobalt, palladium or platinum. Raney-nickel and Raney-cobalt are particularly suitable. After evaporating off the solvent and excess acetic acid anhydride, the reaction product is saponified by boiling with hydrochloric acid. The amine can be isolated from the hydro chloride in the usual way by treating with alkali. Yields of over 90% are obtained by the process described. The hexahydrobenzylamine can serve as starting material for synthetic materials and pharmaceutical products. Example 1. 13.75 Parts of tetrahydrobenzonitrile are dissolved in 150 parts of glacial acetic acid -and-50-parts of acetic acid anhydride. After the addition of 2 parts of Raney nickel, the mixture is stirred in an autoclave at 50"C under 100 atm. hydrogen pressure until the pressure is constant. The reaction is com plete after 3-5 hours. After evaporating off the glacial acetic acid and the excess acetic acid anhydride in a vacuum, the remaining acetyl compound of hexahydrobenzylamine is saponified at the boil with concentrated hydrochloric acid, the amine is liberated by the addition of caustic soda lye and isolated by shaking out with ether or by steam distillation. The yield is 92% of the theoretical. Also finely distributed cobalt, palladium or platinum can be used as hydrogenation catalyst instead of nickel. Example 2. 10 Parts of Raney nickel are added to 117 parts of tetrahydrobenzonitrile and a mix ture of 120 parts of acetic acid anhydride and 85 parts of glacial acetic acid and the whole is hydrogenated - at 75 C under 50

atm. hydrogen pressure until the pressure is constant. After filtering off the catalyst, the acetyl compound is distilled in a vacuum. It passes over at 150-180 C under 10 mm pressure. The yield is 85% of the theoretical. After boiling 100 parts of the acetyl com ponent with 1000 parts of a mixture of equal parts of 15% sulphuric acid and 15% acetic acid for 20 hours and adding an excess of caustic soda solution, the amine can be extracted with ether and recovered by distillation in a yield of more than 90%. Example 3. 312 Parts of tetrahydrobenzonitrile with 500 parts of acetic-anhydride and 200 parts of glacial acetic acid are hydrogenated in the presence of 15 parts of Raney nickel at 70-90"C : while stirring until the pressure is constant at 10 atm. After evaporating off the solvent in a vacuum, the acetyl compound is distilled at 118-126 C under 0.1 mm pressure. The yield is 97%. After boiling 100 parts of the acetyl component with 1000 parts of a mixture of equal parts of 15% sulphuric acid and 15% acetic acid for 20 hours and adding an excess of caustic soda solution, the amine can be extracted with ether and recovered by distillation in a yield of more than 90%. Also Raney cobalt can be used as hydrogenation catalyst instead of Raney nickel. Example 4. 107 Parts of tetrahydrobenzonitrile are dissolved in 150 parts of acetic-anhydride and hydrogenated in the presence of 7 parts of Raney nickel at 70-90 until the pressure is constant at 100 atm. The catalyst is filtered off and the solvent is evaporated off in a vacuum, whereupon the acetyl compound passes over at 145-160"C under 10 mm pressure. The yield is 95%. After boiling 100 parts of the acetyl component with 1000 parts of a mixture of equal parts of 15% sulphuric acid and 15% acetic acid for 20 hours and adding an excess of caustic soda solution, the amine can be extracted with ether and recovered by distillation in a yield of more than 90%.

* Sitemap * Accessibility * Legal notice * Terms of use * Last updated: 08.04.2015

* Worldwide Database * 5.8.23.4; 93p

* GB785109 (A)

Description: GB785109 (A) ? 1957-10-23

Improvements in tools having a pressure fluid driven rotary motor

Description of GB785109 (A)

A high quality text as facsimile in your desired language may be available amongst the following family members:

CH345971 (A) DE1055752 (B) FR1148593 (A) NL101232 (C) US2855671 (A) CH345971 (A) DE1055752 (B) FR1148593 (A) NL101232 (C) US2855671 (A) less Translate this text into Tooltip



SPECI 11 CATIO) keprinted as amended in accordance with the Decision of the Superintending Examiner, adting for the Comptroller-General dated the fifteenth day of April 1958, under Section 29, of Athe Patents Act, 1949 - PATENT' SPECIFICATION 785 109 Date of Application and filing Complete Specification: Feb 22, 1956. No 5510156. Application made in Sweden on March 23, 1955. Complete Specification Published: Oct 3, 1957. Index at acceptance:-Classes 60, DIDI, D 2 A( 17: 19: 21); 81 ( 2), A

2 A; 83 ( 3), B 2 (AI: AS: V), E 1 (A 8 H 2: B 7 D: B 22), K( 3 C 5: 3 K: 7 D: 7 Q 2); and 110 ( 3), B 2 F 3, B 2 V( 3 A: 17: 20 C). Internation Ai Classification:-A 61 c B 23 b, c B 24 b F Old. COMPLETE SPECIFICATION' Improvements in Tools having a Pressure Fluid Driven Rotary Motor We, ATLAS Co Pco Ar TIEBOLAG, of Nacka, Sweden, a Company registered under the Laws of Sweden, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to, be particularly described in and by the following statement:= This invention relates to tools having pressure fluid driven rotary motors, such as grinding machines, drilling machines or the like, and particularly dental machines One object of the invention-is to provide a portable or hand tool which has low weight and small dimensions and is easy to operate and which is particularly fit for replacing conventional belt driven dental drilling machines A further object of the invention is to provide a tool in which the worlking implement, such as a dental burr or drill or grinding wheel is driven by a high speed motor with a suitable number of revolutions of the motor as well as of the working implement A still further object of the invention is to provide a tool in which the rotation of the working implement is immediately discontinued or is very quickly braked when the pressure fluid supply is interrupted A still further object of the invention is to provide a hand tool which is well balanced and fits well in the hand of an operator, such as a dentist. For these and other purposes we provide a tool having a rotary pressure fluid driven motor with a housing and a rotor mounted -35 for rotarion in said housing, yalve means in Pricf 3 s 6 d l said tool for controlling the flow of fluid for driving the rotor, a motor shaft mounted to rotate in the housing and carried through the rotor and rotatable relative to the rotor, a hand-piece provided with means for fitting a rotary working implement and for driving said implement from said motor shaft, and bearings in the housing in which the rotor isl mounted and which are provided one at eachi end of the rotor and comprise sets of rolling bodies running on races, at least one of said sets of rolling bodies running on an outer race with large diameter and an inner race with a smaller diameter and being provided with and cooperating with means for transmitting the rotary motion of said set around the motor axis to the motor shaft, and each one of said sets being arranged to roll on a race arranged for rotation with the rotor and a second race provided in the housing, at least said second race pertaining to the set of rolling bodies which transmits rotation to the shaft being held against the rotation in the housing Further characteristic features of the invention are set forth in the

following description of one embodiment of the invention and in the claims. In the accompanying drawing one embodiment of a tool according to the invention for dental purposes is illustrated by way-of example Figs 1 and 2 are a longitudinal cross section of the tool and Fig 3 is a section on line III-III in Fig 2. The dental tool illustrated in the drawing is provided with a motor housing comprising price 2 785,1 O a front section 1 and a rear section 2 which the forward bearing is loaded or biased by is screw threaded 'in th-fronit s&ction at 3 a spring 25 in the direction towards the turThe front section 1 provides a socket 4 b ine wheel The spring 25 -transmits axial accommodating a hose connection 5 through pressure to the outer race 16 and is fitted which compressed air is supplied to the tool between said race and the sleeve 23 which is 70 from a suitable source A compressed air also axially movable in the motor housing driven rotor 6 is roiatably mounted in the section 1 A rod 26 is slidable lengthwise of motor housing and consists of a turbine the socket 4 and engages an inclined recess or nheel which is supplied with driving air from slot 27 in the sleeve 23 and also serves to 10:an annular admission chamber 7 in the front prevent the sleeve 23 from turning in the 75 section 1 through nozzles 8 in a partition 9 front section 1 around the longitudinal axis Instead of': :turbine a sliding vane motor or of the tool Displacement of the sleeve 23 in any other rotary air motor may naturally be the direction towards the rear section 2 of employed The compressed air supply to the the motor housing causes displacement of the admission chamber 7 is controlled by a rod 26 due to the shape of the inclined bottom 80 spring loaded ball valve 10 disposed in the of the recess 27 on which the rod 26 rests. socket 4 From the valve housing formed by Said displacement lifts the valve 10 from its the hose connection 5 and the socket:4 a -seat -and opens the air supply to the turbine. passage 11 leads to the annular admission A hand-piece is detachably inserted in the 120;chamber 7 The air flowing fromn the turbine' front section 1 of the motor housing and in 85 : 'wheel 6 foiva Mito an annular chamber 12 the illustrated embodiment said hand-piece and 'from there to the aitmosphere through consists of a substantially tubular housing 30 openings 13 directed rearwards and arranged -which fits into a bore in the motor housing in the rear section 2 of the housing The section 1 and is retained in inserted position turbine wheel 6 has axially extended hub by -a fiat circular spring loaded ball lock 28 90 portions 14 fitted in ball bearings onai ach The lousing 30 contains an intermediate side of the turbine wheel, These ball bearings shaft 31 which is mounted in a ball bearing consist

of-inner races 15, outer races 16, sets 32 and-a needle bearing 33 The intermediate of balls 17 and ball retainers 18 The outer,shaft is provided with a claw coupling memrace 16 of the rear ball bearing is press fitted ber 34 which is engageable with a claw coup 95 in tlie: rear section 2 -:of-the-motor housing, ling member 35 fixed on the shaft 20 The whereas the forward ball bearing has an coupling member 35 carries a brake cone 36 outer_ race A& 6 axially-movable in the partition which cooperates with a corresponding brake 9 and keptfrom turning by -an annular -disc cone 37 in the sleeve 23 A spring 38 keeps 19 _of:rubber or other -suitable flexible mater the intermediate shaft: 31 in the position 100 iai L Amnotor-shaft 20 extends freely through illustrated, in-the Figures. a central bore-in-the turbine wheel 6 and the - A zfliat spring 39 which forms a resilient axia Lextensions 14 and is mounted for rota bend is fitted in the housing 30 between an tionin-two ball-bearings 21 and 22 The-ball abutment 40 on the housing and an abut-40 bearing 21 is fitted in -the rear section 2 of ment 41 on the sleeve 23 When the high 105 the motor housing, whereas the balt bearing portion of the fiat spring 39 is pressed to22 is-fitte&din a sleeve 23 in the front section wards the housing 30 the rear end of the 1 wlikh sleeve is axially movable relative to spring 39 which:is guided in the housing 30 te _ball bearing 22 -The ball retainers 18 moves the sleeve 23 towards the turbine f Armeans:rortransmitting rotary motion of causing the old 26 to open the valve 10 and 110 the balls 17 _around the turbine axis to the simu Itaneously the brake cone 37 to disenshaft 20 ( For this purpose the ball retainers gage b rake cone 36 so -that the turbine 18 are connected -to the shaft 20 by means may rotate and drive the-motor shaft 20 and of pins 24- extending-transv-er-sely through -the the intermediate shaft: 31 An increased presball retainers andthe-shaft In -view of-the sure on the flat spring 39 produces an in 115 fact that the balls 17 rotate-around-the tur creased displacement of the sleeve 23 and bine axis _which_ is -_the longitudinal axis of increased tensionfa of the spring 25 which the tool _with a number of revolutions which increases the -frictional contact between the is less than half the number of-evolutions balls:17 and the races 15 and 16 so that an -: 5 5 of the turbine _wheel:6 -thezballs function sub increased turbine torque may be transmitted 120 stantially asthe planetary wheels-of -a plane through the friction transmission. tary friction gear the number of -revolutions ' -i Ttie intermediate shaft 31 is provided with of the shaft 20 being less than half the nuni a c Qhufick 45: screw threaded into the intermedhe Yt of revolutions of the turbine wheel 6 ate shaft In the chuck a cylindrical shank The abity Qfthe:ball retainers 18 to trans Qf a n Qt

illustrated working implement such 125 mit a:orque t the shaft 20 naturally te as a dentist's burr, a grinding wheel, apolishpends-on:thefrictional contact-between the ing wheel or-other working implement may balls 17 and the inner:races 15 and outer be inserted The chuck 45 has an internal ra Ces 16 -I orfder to maintain such frictional tapering portion at the rear end which taperco Utact the axially;movable outer race 16 of in portion cooperates with an external taper 130 ing portion 44 of an axially slotted clamping one at each end of the rotor and comprise sets sleeve 43 which is fitted in the bore 29 in of r 6 olling b 6 dies running on races, at least the intermediate shaft 31 and serves to retain one of said sets of rolling bodies running on the worldking implement In order to fix the an outer race with larger- diameter and an working implement in the chuck the shaft 20 inner race with smaller diameter and being 70 is provided with a knob 46 at the: rear end provided with and cooperating with means which extends from the rear section 2 by for transmitting the rotary motion of said set means of which the shaft 20 and the inter around the motor axis to the motor shaft, mediate shaft 31 -may be turned manually and each-one of said sets, being arranged to relative to the hand-piece -30 Furthermore, roll on a race arranged for rotation with the 75 the hand-piece 30 with the bearing 32 is disc rotor and a second race provided in the housplaceable on the intermediate shaft 31 to ing, at least said second race pertaining to the wards the motor housing 1, 2 and against the set of -rolling bodies which transmits rotation action of the spring 38 Through movement to he shaft being held against the rotation in of the hand-piece 30 towards the motor hous the ihousing 80 ing ftom the illustrated position, in which the 2 -A tool according to claim 1, in which ball lock 28 engages an annular groove 47 in said motor shaft extends through the rotor the hand-piece 30, claws 48 formed on the and is free to rotate relative to the rotor arnd chuck 45 engage and are retained by recesses relative to the housing, an intermediate shaft 42 in the inner front end of the hand-piece mounted to rotate in said handpiece, and a 85 30, In this position turning of the intermed coupling between said shafts forming a drivfate shaft 31 by means of the knob 46 causes ing connection between the shafts. the chuck 45 to be threaded in or out of the 3 A tool according to claim 2, in which a intermediate shaft 31 and when the chuck chuck is provided in said hand-piece for 45 is threaded into the shaft 31 the slotted receiving a shank of a working implement, a 90 clamping sleeve 43 is tightened since the portion of the motor shaft extending through internal taper of the chuck 45 encloses the the rear end of the housing and carrying a corresponding external taper 44 of the clamp knob outside the housing, said knob serving ing sleeve 43 and tightens

said sleeve around to manually rotate the motor shaft and the the shank of a tool (not illustrated) which is intermediate shaft in order to operate said 95 inserted in the chuck and the clamping sleeve chuck to engage or to release said shank, Loosening of the working tool implement is respectively. produced by turning the knob in the opposite 4 A tool according to claim 1, in which direction braking means are provided for braking the The dental tool above described rotation of said motor shaft, and means are 100 and illustrated in the drawing should provided between the working implement only be considered as an example receiving end of said hand-piece and the rotor and the details of the invention for operating said braking means to engage or may be modified in several different ways disengage the braking means. within the scope of the claims Instead of the 5 A tool according to claim 4, in which 105 ball valve 10 controlling the pressure fluid valve means are provided for controlling the supply to the rotor a valve mechanism may flow of fluid for driving-the rotor, and in be provided which controls the exhaust ports which said operating means for the braking of the turbine or other motor The illustrated means is cooperatively associated with said straight hand-piece may naturally be replaced valve means to reduce the flow of fluid or fo 110 by an angle type hand-piece as is conventional interrupt the flow of fluid simultaneously in connection with dental tools The tool may with engaging the braking means. also be used for other than dental purposes 6 A tool according to claim 1, in which for instance as a grinding or milling machine means are provided for regulating the fricfor intricate jobs such as manufacture of tional contact between the rolling bodies and 115 pressing or forging tools, artist's sculptural said races. jobs, or the like 7 A tool having a rotary motor with a

* Sitemap * Accessibility * Legal notice * Terms of use * Last updated: 08.04.2015 * Worldwide Database * 5.8.23.4; 93p

* GB785110 (A)

Description: GB785110 (A) ? 1957-10-23

Electron tube magnetic focusing device


A high quality text as facsimile in your desired language may be available amongst the following family members:

US2843775 (A) US2843775 (A) less Translate this text into Tooltip



PATENT SPECIFICATION 785, 110 c RI Date of Application and filing Complete Specification: Feb 28, 1956. No 6113/56. Complete Specification Published: Oct 23, 1957 - Index at acceptance:-Class 39 ( 1), D( 1 OD: 16 A 1: 46 A). International Classification:-H Olj. i COMPMETE SPECI'FI CATION Electron Tube Magnetic Focusing Device We, STANDARD TELEPHONES AND 'CABLES LIMITED, a British Company, of Connaught House, 63, Aldwych, London, W GC 2, England, do hereby declare the invention, Communicated by Nippon Electric Company Limited, a Japanese Gompany, of 2 Shiba Mita Shikoku Machie, Mziaato-ku, Tokio, Japan,, for which we pray that,a patent may _be granted to us, and the method by which it is to be performed, to be particullarly described in and by ithe following statement: - This invention relates tothe magnetic focusing devices for focusing a long electron, beam and more particularly to such devices for use in 15 eleotron tubes, such as the travelling wave tube. In electron tubes, such as travelling wave tubes and the like, axial magnetic fields have been;used for maintainling the diameter of an electron beam within an approximately fixed value over a long range In such systems the magnetic field is not necessarily a uniform magnetic

field bt it is well known, that a magnetic field which varies in magnitude somewhat in,the manner of a sine wave can be used to produce periodic exact focusing and still mainwain the beam within limits of the desired diameter. (In a known form of the magnetic focusing arrangement there are provided a plurality of annular permanent magnets arranged with like poles faoing each other and with magnetic yokes extending radially inward of the cylinder formed by these magnets into proximity mwith the electron beam It is desirable that ithe magnetic yoke pieces extend as close,as possible to the beam in order to exert the maximum focusing control However, when they are brought into,close proximity with the beam the electro-magnetic wave may excite the cavities existing intermediate the yokes and thus induce unwanted effects which may adversely d'stort the energy being,amplified or the electron beam itself. In accordance with this invention there is provided a magnetic focusing means for an electron 'beam comprising a plurality of annular magnetic means positioned end-to-end to (Pricee provide a cylindrical struoture, annular yokes of miagnetic material positioned intermediate said magnetic means and extending radially inwardly of said cylinder to produce magnetic effects in dclose proximity to ithe beam, and means for avoiding unwanted resontance effects by the cavities intermediate said yokes comprising non-magnetic metallic means intermediate,adjacent of said yokes at their inner peripheries bridging the gaps therebetween. Embodimenrts of the invention will be descilibed with reference to the accompanying drawings, in which:' Fig 1 is a oross-sectional view of a portion of a magnetic electron beam focusing device incorporating the feature of this invention, and -Fig 2 is 'a similar seational view of a further modified form of this invention. Turning now to Fig 1, the envelope of a travelling wave tube is shown at 1 having disposed therein the usual helix The electron beam traverses longitudinal of the envelope 1 within, the helix Externally of the envelope 1 are provided a plurality of magnets 2 shown as permanent magnets These magnets are arranged so that like poles face each other and intermediate the poles of the magnets are provided yoke m'embers 3 extending radially inwardly of the magnet The yoke pieces 3 are distributed along the axis of the tube so as to form an approximate sine wave curve of the magnetic flux along this axis Intermediate the inner peripheries of adjacent magnetic yokes 3 are provided rings 4 of non-magnetic material In the form shown rings 4 have a step projection so as to inter-ilt with projeotions on the yoke pieces However, it is clear that these may be fastened in place by either means such as brazing or soldering and it is not necessary that

such interfitting be provided. With this type of construotion the magnetic yokes may be brought into as close proximity as possible to the electron beam so as to provide the maximum focusing effect However, because of the continuous conductive cylinder formed by the inner peripheries of,the miagnetic yokes 3 and the rings 4, the electro-mag-70 netic waves cannot excite the resonant volumes which exist intermediate these yoke members As a result the magnetic assembly may be positioned as close to the beam as is possible without disturbing the frequency response of the beam because of the resonant cavity effects. In Fig 2 there is shown a magnetic asseimbly substantially similar to that shown in Fig. 1 However, in this construotion instead of using the inner peripheries of the magnetic yoke assemblies to form the continuous cylinder for shielding from the electro-magnetic effects, there is provided a composite cylinder composed of rings of magnetc material 6 aniid rings of non-m'agnetic aaterlal 4 forming a substantially continuous cylinder outside the envelope 1 of the tube The rings of magnetic material 6 are made,to extend along the cylinder substantially the same longitudinal length as the inner peripheral surface of the magnetic yokes 3, while the non-magnetic rings 4 substantially bridge,the gap that otherwise would exist between these magnetic yokes. Thus,there is provided a -continuous magnetic focusing system similar to that described in Fig 1 and having similar advaantages However, in this construction the cylinder and the magnetic yoke assembly may be separately constructed and then assembled so as to be properly positioned as shown While the invention has been, described in connection with specific embodiments thereof using permanent magnets, it is clear that the principles thereof equallyl iapply to systems using a plurality of individual electro-magnets with the siilarly shaped magnetic yokes.


* GB785111 (A)

Description: GB785111 (A) ? 1957-10-23

Improvements in and relating to tractors


c PATENT SPECIFICATION Inventors: ALBERT FREDERICK JOHN PINK and JOSEPH DAVEY 785 j,11 Date of filing Complete Specification (under Section 3 ( 3) ofthe Patents Act, 1949)Jan 29, 1954. Application Date Feb5, 1953 No 3336/53. Application Date Sept11, 1953 No 25206/53. Complete Specification Published Oct 23, 1957. Index at acceptance: -Classes 68 ( 1), F 12; and 79 ( 1), El K, T 3 K. International Classification: -B 62 d E 21 c. COMPLETE SPECIFICATION Improvements in and relating to Tractors We, W E BRAY & COMPANY LIMITED, a ment to the arms are preferably carried on the Company organised under the laws of Great brackets. Britain, of Fagg's Road, Feltham, Middlesex, The aforesaid means for imparting up and 50 and COUNTY COMMERCIAL CARS LIMITED, a down movement to the forwardly extending Company organised under the laws of Great arms which carry the ancillary implements may Britain, of Fleet, Aldershot, Hampshire, do comprise hydraulic or other jacks. hereby declare the invention, for which we By means of the present invention it is pospray that a patent may be granted to us, and sible, with the use of unskilled labour, for a 55 the method by which it is to be performed, to standard tractor, such as that known under be particularly described in and by the follow the Registered Trade Mark "Fordson " to be ing statement: converted into-an angle-dozing or other opera- This invention relates to track laying and tive unit and the handling capacity of the wheeled tractors of that known kind compris equipment to be matched to the power avail 60 ing an engine unit, a transmission unit and able from the tractor engine Furthermore, in back axle unit the casings of which units the case of a dozer blade, -it has the advantage together form the frame and body of the that the overall length of the mouldboard can tractor and hereinafter referred to as the be reduced while still remaining sufficient to chassis give

coverage to the overall width of the trac 65 The purpose of this invention is to enable tor unit when in its angle-dozing position, that ancillary equipment, such as an angle-dozer or is with the mouldboard or blade inclined to the bulldozer equipment, with reference to which longitudinal axis of the tractor at an angle of'. the invention is hereinafter illustrated, to be 25 -30 This relative reduction in length fitted to a tractor not originally designed for of the mouldboard is obtained by fitting it in 70 this purpose in such a manner that no undue this manner permits the successful operation stress is transmitted to the chassis and with of the tractor in more confined spaces and out in any way detracting from the usefulness under more arduous conditions where the of the tractor as a towing vehicle A further greater power per unit length of blade is purpose of the invention is the strengthening required 75 of the existing spring system to take the addi A tie rod may be connected to and extend tional loading imparted by the ancillary equip rearwardly from each bracket and is arranged ment for connection with the back axle casingsAlso According to another aspect of the invention each said bracket may have a part extending equipment for a tractor which is required to rearwardly and arranged for connection to the 80 move implements under heavy loads, com chassis in the neighbourhood of the back axle. prises two brackets, each having means for This arrangement ensures that the thrust set connecting it to the tractor and which brackets, up by the ancillary implements, when in use, when fitted to the tractor, are adapted for will be transmitted to the rear axle of the tracattachment to opposite sides of the tractor tor without imposing any offset or additional 85 chassis, two forwardly extending arms loading of the track frames pivotally connected respectively to said The invention is illustrated in the accorm-. brackets so as to swing in an up and down panying drawings as applied to a tractor, in direction, means for imparting pivotal move which: ment to each said arm and spring means Figure 1 is a perspective part-exploded view 90 attached to anchorages on the brackets for con of a tractor showing the bracket and -the meansnection to mountings for wheels or tracks and of attaching it to the tractor chassis and the extending laterally of the brackets The means anchorages for the additional springs: on each bracket for imparting pivotal move Figure 2 is an elevation, and lPricr 3 s 6 d l pi ii 1 t i i i 11 i i 1 i i i R i i i 785,111 Figure 3 is a plan view of a track laying tractor fitted with a modified design of bracket having an extension arm; Figure 4 is a front end-on-view showing the track laying tractor dozer unit of Figures 2 and 3.

In the drawings there is shown a tractor comprising a chassis C (Fig 3) having members indicated at L which extend along both sides E indicates the engine unit. The endless tracks as shown in broken lines at T, and the track sprockets at -S, S', each track and sprocket unit being mounted on a longitudinally extending box frame F Transverse springing M (see Fig 4) is secured to the chassis C and interconnects it with the frames F, the springing M hereinafter being referred to as, the main springs M. While the invention is hereinafter described in relation to a track-layipg tractor it can be applied to wheeled tractors Most wheeled tractors have a rigid centrally suspended wheel axle, springs not being standard especially in a two-wheel drive. In four-wheel tractors where drive to the = front wheels is through a chain in a casing which has a fulcrum on the rear axle it is the practice to provide front or main springing between the chain drive casings and the chassis An example of such a tractor is that known as the " County Fourdrive ". The invention is illustrated as applied to dozing equipment which comprises a blade A attached by radius arms B to a girder frame comprising forwardly extending arms D, this part of the equipment being more or less standard. In carrying out the present invention there is provided an auxiliary bracket 1 for attach40, ment to the chassis of the tractor on each side thereof In practice, the wheels or tracks of the standard tractor are first removed and then by attaching the auxiliary brackets consisting of plates 1, to the chassis, the latter is suitably reinforced to carry the ancillary equipment, e g a dozer blade and actuating mechanism therefor The auxiliary brackets may be fixed by a set of screw studs 2 to the sides C of the chassis The standard wheels or tracks are replaced by a track or wheel mounting F which as compared with the normal mounting is strengthened to withstand the additional loading imposed by the ancillary equipment and which as explained later in connected to the bracket by an additional spring 6, one of the main springs being indicated at M (Figure 4). Thus it is possible to convert a normal tractor to a dozer tractor at comparatively low cost. As shown in Figure 1 the brackets 1 each include a forwardly extending arm 3 in which are stud holes 4 which secure the extension 3 to a part L which carries the radiator There are also four stud holes -2 by which the extension and brackets are secured to a part of the chassis Each bracket 1 includes a forwardly extending arm 3 in which are stud holes for the studs 2 and having at its front end further stud holes 4 for other fixing studs, which secure extension 3 to a part L which carries the radiator Each bracket 1 includes a laterally 70 projecting

step piece 5 to provide a seat for the fixing of a quarter elliptical type spring 6 whose outer ends bear on a saddle plate 7 carried by the wheel or track mounting F In the drawing the track mounting F is shown 75 supporting an endless track T which encircles sprocket wheels S and S' Each saddle plate 7 has upstanding -guides 8 and is fixed to an inverted U-section or girder frame 9 forming part of the wheel or track mounting F and also 80 serving to house recoil springs The additional springs 6 are preferably of multiple leaf type and positioned at the point of balance of the chassis Instead of leaf springs coil springs may be fitted, which entails extending the step 85 plates 5 The saddle plates 7 are arranged above the recoil spring housings on the wheel or track mounting F, which housing free to react against any immovable obstruction met by the tracks through the main recoil springs 90 in the recoil spring housing and as such is capable of swinging in an up and down direction about a transverse axis in known manner. The plates forming the brackets 1, as can be seen from Figure 1 extend downwardly below 95 the chassis and carry laterally projecting pins 10, which provide fulcrums for the support frame D of the dozer blade For convenience of assembly when converting a standard tractor, which can be done by unskilled labour, 100 the frame D is provided at the rear end of each of its arms with a detachable block 11 forming one half of a split housing encircling a bearing sleeve, the other half 11 of the housing being in the end of the arm A resilient bush 12 may 105 be fitted over the pin 10 and is received in the split housing 11, 11-. At its upper end each bracket plate 1 is preferably formed, as shown, with a forwardly over-hanging part 13 provided with a fulcrum 110 pin 14 which pins constitute anchorages for the operating mechanism of the dozer unit. This mechanism may consist of hydraulically operating rams, one arranged at each side of the chassis frame and including a cylinder 15, 115 one end of which is provided with a bearing sleeve 16 to receive a bush formed preferably of rubber or other resilient material and mounted on the anchorage pin 14. Slidable within the cylinder 15 is a piston 120 which may be double acting and has a piston rod 151 carrying at its end a socket 17 in which is journalled a trunnion element 18 for engagement with lugs 20 on the dozer frame D The element may likewise be fitted with a resilient 125 bush By fitting resilient couplings such as those known under the Registered Trade Mark " Silentbloc " into the crank joints of the jack elements and linkage members, it has the advantage that not only do they absorb any 130 785,1 lii 3 shock, but accommodate any misalignment that might occur.

In order to counteract any bending movements, to which, the rear axle casings may be subjected, the tie rods 22 (not shown in Figure 1 but shown in Figures 2 and 3) may be fitted between the plates 1 and points 23 at the ends of the rear axle casings. Referring now to Figures 2, 3 and 4 there is shown a tractor fitted on each side thereof with a modified design of bracket comprising a plate 1 having a rearwardly extending arm for connection to the rear end of the chassis by means of pedestal plate 26 In this modification the plate is not provided with a forwardly extending arm but is secured direct to the part L which carries the radiator As in the previous arrangement the plate is provided with four stud holes through which the studs attached to the chassis loosely extend The pedestal plate 26 in the embodiment illustrated is secured to the transmission housing, to which the rear axle casings are mounted and are each provided with a boss 27 having a pivotal mounting for the arm 25. The provision of the arm 25, it will be appreciated, relieves the bolts, by which the bracket is secured to the chassis, of torque or shear set-up, such as when the tractor is driven forwardly to drive the dozer blade into the ground, and similarly when the latter or other ancillary equipment, e g a bucket, by which the dozer blade may be replaced, is raised to an elevated position and to ensure this relief clearance is provided in the holes through which the bolts extend. The tie rods 22 by which the brackets are additionally stayed, are secured at their forward ends by bolts to the plates 1 and at their rear ends by means of collars 29 to the rear axle casings. It should be understood that while the present invention has been illustrated as applied to the conversion of a standard tractor to a track laying tractor for operating dozing equipment, it is equally applicable to a half-track machine where half-tracks are fitted to the rear of the tractor and the front wheels are used for steering in the normal manner It should also be appreciated that in place of fitting tracks, the normal wheels can be removed and replaced by extra large size wheels, both as regards the driving wheels and the steering wheels.


* GB785112 (A)

Description: GB785112 (A) ? 1957-10-23

Improvements in the treatment of hides, skins and tanning liquors therefor

Description of GB785112 (A) Translate this text into Tooltip



PATENT SPECIFICATION 785,112 V/ ODate of filing Complete Specification: Feb 18, 1954. Application Date: Feb 26, 1953 No 5362 /53. Complete Specification Published: Oct 23, 1957. Index at Acceptance:-Classes 76, C 2 (A 2: G), C 2 I( 1: 3 B: 6 9), C 2 J( 3: 4: 7), C 2 X, E; and 121, B. International Classification:-C 09 h C 14 c. COMPLETE SPECIFICATION. in the Treatment of Hides, Skins and Tanning Liquors therefor. We, DONALD BURTON, a British Subject, of 2 Eccleston Court, Kirkstall Lane, Headingley, Leeds 6, in the County of York, RONALD REED, a British Subject, of 3 Woodhall Park Avenue, Stanningley, Leeds, in the County of York, and FRANCES OLGA FLINT, a British Subject, of Faversham Hotel, Mount Preston, Leeds 2, in the County of York, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with improvements in or relating to the treatment of hides and skins It relates mainly to the treatment of hides and skins prior to tanning, or conversion into raw hide products, parchment, gelatine, and glue, but is also concerned with the treatment of tanned hides and skins, and also with improvements in tanning liquors.

Mucoid materials or muco-polysaccharides are present in hides and skins Such materials are essentially polymers of sugar-like compounds, usually, though not invariably, formed by the linking together of simple sugars or amino-sugars with simple sugar acids, or with other, or the same simple sugars so that long, chain-like molecules are formed Such sugars include substituted and chemically modified sugars such as acetylated, methylated, sulphonated sugars and the like The sugar acids and their compounds with alcohols are included as well as their salts Mucoid materials are therefore quite distinct from the proteins, which are essentially polymers of various types of amino acids Mucoid materials are found in close association with all the protein structures of hides and skins and the regions where they are present in rich amount include the epidermal-corium junction, the elastic tissue fibres, the corium fibres and the spaces between these fibres. The stability of the protein structures is i 45 determined by the mucoid materials in which they are embedded If the mucoid materials are modified, reduced in amount or removed entirely, the protein structures remaining are loosened and their cohesion is greatly 50 modified. An object of the present invention is to provide an improved process for the depilation of hides and skins. Another object of the invention is to pro 55 vide a process for the treatment of hides and skins which enables hair, wool or other keratinous covering structures to be obtained in substantially undamaged condition and therefore of high quality 60 Yet a further object of the invention is to provide an improved process for treating hides and skins to render them more suitable for tanning and other purposes. Another object of the invention is to pro 65 vide a skin or hide in which the grain surface or layer is very tight and smooth and free from distortion. Yet another object of the invention is to provide improved tanning liquors 70 According to the present invention, a process for the treatment of hides and skins consists in treating the hides and skins with a composition which is capable of modifying the mucoid material naturally present in 75 said hides and skins and comprising between 0.25 and 50 % of a commercial preparation of a carbohydrase or mixture of carbohydrases and a buffer solution within the range p H 3-p H 12 5 80 A carbohydrase when used under the conditions of p H value and temperature approImprovements priate to it, will attack and/ or degrade and/or digest mucoid materials or mucopolysaccharides, as hereinbefore defined. Carbohydrases include polygalacturonidase, elastase, pectinase,

hyaluronidase, chondroitinase, and diastase, or as it is equally often referred to, amylase. The term "carbohydrase" has been used throughout the present Complete Specification in preference to the term "mucolytic" used -throughout the Provisional Specification, in view of the fact that in "Chemistry & Technology of Enzymes"(Tauber, 1949) the scope of the term "mucolytic" is defined more narrowly than the interpretation intended to be given to this term when used originally in the present Provisional Specification. The treatment of the hides or skins with carbohydrases can be carried out either at the beginning or at any one or more subsequent stages of conversion into leather and other products of hides and skins Thus for example, as we shall explain later, we have found it advantageous to employ a carbohydrase or mixture of carbohydrases under the special conditions which we shall e Iaborate, for the soaking back of fresh or salted or dry-salted or dried or otherwise preserved or treated -hides and skins, for the removal of hair, wool, fur or other keratinous covering structures, for the loosening of the fibrous structures, for the loosening of the fibrous structures of the corium or dermis of such 36 hides and skins, and for bating them It is possible to accomplish all these processes in one operation, but the operator may wish, after soaking back, or liming, or de-liming, or bating by practices already known to the art of leather making, to introduce our process involving the action of -a carbohydrase or mixture of carbohydrases. We do not wish to restrict the use of our process to operations before tanning, for we envisage its application to tanned material and to material which has been dyed and/or -fat-liquored and/or finished By hides and skins, we include also woolskins e g sheepskins and fur-bearing skins or pelts Also so pieces of such hides and skins, including the tails of fur-bearing animal skins, such as are used in the manufacture of paint and other types of brushes By pieces of hides and iskins, -w& mean -to include also pieces of limed or tanned hides and skins and any such trimmings which are normally used for the making of gelatine and glue; also we wish to include pieces and trimmings of wool and fur-bearing skins and pelts, both in the tanned and un-tanned condition Preserved or treated hides and skins means hides and skins at all stages of processing including the finished product. The use of our process is meant to apply to all types of tannage and treatments used for the hides and skins, pieces, trimmings, etc. It is usual in depilation processes to adopt a process involving the use of lime and a sulphide, such as sodium sulphide, for separ 70 ation of the hair and epidermis from hides and skins, or to use

proteolytic enzymes obtained from bacterial, mould, animal and plant sources. Such proteolytic enzymes bring about 75 depilation by disrupting and/ or digesting the essential protein structures of the epidermis and the epidermal-corium junction, but these proteolytic enzymes have no intrinsic action on the mucoid materials present in 80 hides and skins. It has now been found in accordance with this invention that carbohydrases, which do not attack and/or digest the protein structures, but only the mucoid materials, are 85 effective in loosening the epidermal-corium junction of hides and skins and in detaching the epidermis and its elaborated structures such as hair, and sweat glands, entirely from the corium Carbohydrases attack the 90 mucoid material which is present at the epidermal junction and which embeds the protein structures at this junction Before subjecting the hides and skins to the action of a carbohydrase or mixture of 95 carbohydrases according to our invention the operator can, if he so wishes, soak them back according to the well established practices of the leather trade Thus, for example, he can soak the hides and skins in water 100 with or without alkalis, wetting agents, bactericidal agents and similar reagents commonly employed in soak liquors, without prejudice to the subsequent treatment with a carbohydrase or mixture of carbohydrases 105 Further the operator can, without prejudice to the subsequent treatment with a carbohydrase, subject the hides and skins to the mechanical operations of breaking, fleshing, and the like 110 This prior treatment of conventional soaking the hides and skins, can, at the discretion of the operator, be dispensed with as we shall describe later The soaked hides and skins are placed in a solution containing the 115 carbohydrase or mixture of carbohydrases at a p H value appropriate to the particular enzyme or mixture of enzymes used By solution at a p H value appropriate to the particular enzyme -or mixture of enzymes 120 used, we mean a buffer solution, that is an aqueous solution which by its intrinsic chemical composition can maintain its p H value approximately constant and so is able toresist, or act as a buffer against, changes 125 in its p H value when hydroxyl or hydrogen ions are added to it In selecting such a buffer solution appropriate to the enzyme or mixture of enzymes used, we do not restrict ourselves to any one buffer solution for the 130 785,112 785,112 carrying out of our process We have found however that it is advantageous when using a carbohydrase or mixture of carbohydrases to maintain the p H value of the solution approximately constant whilst subjecting the hides and skins to the action of the enzyme or enzymes Preferably the concentration of the buffer solution is 0 25 to 10 % by weight.

By suitable choice of carbohydrase or mixture of carbohydrases, hides and skins may be unhaired at p H values which are lower than those obtainable in the usual liming process, and the high p H values used in the latter process can be avoided Diastase has, for example, an optimum effect at p H 6 5, pectinase at about p H 4 0, and pancreatic elastase at about p H 8 9 Thus any distortion of the grain due to rapid swelling or :20 plumping at very high p H values can be avoided, and it is possible to control grain quality by choosing a carbohydrase with an appropriate optimum p H value Improved grain surfaces can be obtained at any p H in the range 3-12 5 p H. It has been found, by experiment, that the concentration of the carbohydrase or mixture of carbohydrases should generally be of the order of 1 % by weight of commercial preparation for the most beneficial results. As a matter of expediency, it is found to be convenient to employ temperatures in the range 15-35 ' C but it must be understood that this is the preferred range of working and marginal variations at either end of this range may on occasion be used with advantage and are included within the scope of the invention In using our process, we find it advantageous to maintain the temperature reasonably constant at the value decided by the operator, throughout the duration of the treatment of the hides and skins For cowhide, calf skin and woolskins, we have found it preferable for the best results to maintain the temperature of the buffer solution containing the enzyme or mixture of enzymes at about 30 ' C throughQut the treatment For goat skins, we prefer to maintain the temperature at about 350 C. throughout their treatment It is to be understood however that the particular temnperature used may be varied at the discretion of the operator who may wish to employ lower temperatures with a correspondingly longer time of treatment. The hides and skins can be treated with the enzyme or enzymes under the conditions already described, in a drum, paddle or pit or vat or any suitable container, either with or without agitation, and/or aeration. The hides and skins are treated with the enzyme or enzymes according to the conditions already described for periods ranging from 2 hours to 7 days or more The period. during which the hides and skins are subjected to the action of the enzyme or enzymes may be selected by the operator to fit in with his preferred cycle of daily operations, the type of hide or skin being treated and the particular buffer solution, enzyme or 70 enzymes, and the temperature of working employed. With certain hides and skins, and using a paddle or a drum, the hair and/or wool may be detached during the enzymatic 75 treatment as a

result of mechanical agitation or aeration Alternatively, after the selected period of contact with the enzyme or enzymes solution, the hides and skins may be withdrawn and unhaired or dewooled by 80 practices normal in the leather and fellmongering trades By these means, hair, wool, fur and other keratinous structures may be obtained, together with pelt The hair, wool, fur and other keratinous struc 85 tures are of high quality, in that these protein structures are undamaged by the action of the carbohydrase or carbohydrases, only the material cementing such protein structures to the dermis or corium of the hide 90 or skin being loosened and attacked by such enzymes For these reasons, fibres of hair, wool, fur and other keratinous structures may be obtained which are of high quality and which are generally longer than those 95 obtained by existing methods, in that they still possess the entire original, natural length. In the method for the depilation of hides and skins described hereinbefore, the expres 100 sion buffer solution containing enzyme or mixture of enzymes, means that the enzyme or mixture of enzymes is added to the buffer solution before the hides and skins are introduced We do not preclude, however, the 105 addition of further amounts of enzyme or enzymes to the solution, whilst the hides and skins are being treated Indeed, in most cases it has been found advantageous to add further quantities of enzyme or en 110 zymes at appropriate intervals of time. We have found that in addition to using the carbohydrase, or mixture of carbohydrases, in conjunction with buffer solutions as described previously, it is beneficial 115 to include simple salts of mineral acids such as sodium chloride, sodium sulphate, potassium chloride in the solution used for treating the hides and skins We have found that such salts, or mixtures of such salts, 120 added to the buffer solution in concentrations up to as much as 10 % by weight are beneficial for a number of reasons Firstly, such salts control the degree of swelling or plumpness of the hide or skin; secondly, 125 they activate the enzyme or enzymes and so provide for more economical working; thirdly, they aid in the dispersion and solution of the cementing interfibrillary material loosened by the enzymatic action 130 We have also found that we can with advantage use one or more carbohyrases in conjunction with buffer solutions and temperature control for the depilation of hides and skins by a further method of working. This consists in allowing the hides and skins to remain in the enzyme solution or solution of enzymes made up as previously described for suitable period of time, with or without agitation of the system The hides and skins are then withdrawn so that enzyme solution is retained by the hair, wool or fur The hides and skins are then allowed to stand

in piles, at temperatures in the range 15 to 35 ' C By piles we mean stacking the hides and skins' either flesh to flesh, or hair side to flesh, or hair to hair After standing in piles, the hides and skins may then be unhaired or de-wooled according to known practices of the arts of leather making and fell-mongering. After preliminary treatment by the enzyme or enzymes 'as described above, the hides or skins may alternatively be hung in chambers or enclosed spaces maintained at any suitable temperature Individual hanging provides the means for better temperature control. Our invention also provides a method of de-wooling sheepskins and dehairing hides and skins which comprises applying to the flesh side of the skins a "paint" composition comprising one or more carbohydrases, a buffer solution of p H value appropriate to 326 the enzyme or enzymes chosen, and salts such as sodium chloride, sodium sulphate, -potassium sulphate, calcium chloride, etc. These components are mixed with a =thickener, which may be flour (all types such as wheat, maize, barley, soya flour, etc), starch, bran, gelatin, etc, so that a paste of the desired consistency is obtained; the paste is painted onto the flesh side of the skins and allowed to remain on the piled or hung skins or hides for a suitable period of time and the loosened wool or hair subsequently pulled from the skins or hides. The concentration of the one or more carbohydrases in the paint composition should -be at least 0 25 % by weight of commercial preparation. A composition comprising 0 25 to 50 % by weight of a commercial preparation of a carbohydrase, up to 90 % by weight of a thickener such as flour, starch, bran or gelatine and a buffer solution of p H value within the range 3-12 5 and of concentration within the range 0 25 %/o to 10 % by' weight of the composition is particularly effective. In accordance with conventional methods for treating hides and skins -preparatory to -tanning, in addition to depilation, it is necessary to loosen the fibrous structures of the corium This is generally accomplished by liming and by subsequent "bating" According to the present invention, the fibrous structures can be loosened by the action of one or more carbohydrases Although it is possible by the present invention to prepare 70 hides and skins ready for pickling and tanning in one operational treatment with these enzymes, we have found that hides and skins unhaired or de-wooled by existing practices can be conveniently and rapidly "loosened", 75 as a further preparation for tannage, by subjecting them to the action of one or more carbohydrases in the manner hereinbefore described. Thus hides and skins which have been 80 both unhaired or de-wooled and

partially "loosened" as a preparation for tannage, may be further prepared for tannage by "bating" with carbohydrases. -By the terms "loosened" and "partially 85 loosened" is meant the removal of more or less of the interfibrillary mucoid cement material, in which the protein structures of the hide or skin are embedded In the prior art, this necessary operation of rendering the pelt 90 structure more open is termed "loosening" or "opening up" and is accomplished in the process of liming. Further, we have found that even after tannage by existing and conventional 95 methods, the hides, skins, sides, pelts, etc, may with advantage be treated with a carbohydrase or carbohydrases in the manner hereinbefore described Tanned stock needs to be evenly loosened and opened up so that 100 the subsequent processes of dyeing, fat liquoring and finishing may be carried out evenly and satisfactorily We have found that the treatment of tanned stock according to our invention is particularly useful in the 105 making of gloving and suede leather A treatment of half an hour, or longer according to the nature of the leather, with one or more carbohydrases, in the manner hereinbefore described, has been found to im 110 part softness and suppleness to the tanned stock We have found als-o that' dye'stnffs and fat liquors-as applied in subsequent conventional operations now go on to the tanned stock so treated, much more evenly, 115 so that more level shades of dying can be obtained Certain dyestuffs are also found to penetrate the hide or skin far more easily. This is of importance when light and even pastel shades -of dyed leather are required 120 and also in making of suede skins and sides, in that penetration of the dyestuff is much greater and more even. We have found that in treating tanned, or partly tanned, stock with carbohydrases in 125 the manner hereinbefore described, it is advantageous to restrict the p H value of the enzyme bath to a value within the range 3 to 8 We have' found that treatment of tanned stock with carbohydrases at p H '130 785,11 Iv a difficult matter One object of the present invention is to improve the soaking back operation on hides and skins by subjecting them to the action of one or more carbohydrases which can attack and loosen the 70 mucoid components of the interfibrillary cement material This is accomplished by subjecting the fresh or salted or dry-salted or dried or otherwise preserved or cured hides and skins to the action of carbo 75 hydrases in substantially the same manner as hereinbefore described for the depilation of hides and skins by these enzymes The fresh, or salted or dry-salted or dried or otherwise preserved or cured hides and skins 80 are introduced into an aqueous buffer solution, of p H value appropriate to the carbohydrase or carbohydrases selected, containing such enzyme or enzymes, and sodium chloride in concentrations ranging

from 0 to 85 % by weight at a temperature maintained within the range 15 to 350 C, for a suitable period of time The penetration of the enzyme solution may be facilitated by the inclusion of a wetting agent in the solution 90 or by previous treatment of the said hides or skins with a solution containing a wetting agent After soaking back has been accomplished by this treatment, the operator can if he so wish, leave the hides or skins in 95 the same aqueous buffer solution containing the components hereinbefore mentioned in connection with depilating, loosening or bating for a further period of time so that depilation, and/or loosening of the fibrous 100 structures of the corium or dermis, and/or bating may be achieved in the manner hereinbefore described On the other hand, the operator may after soaking by the method of our invention, withdraw the hides and 105 skins from the enzymatic solution and further treat them by conventional methods as used in the arts of leather making, fellmongering, raw hide, parchment, gelatin and allied trades 110 In using our compositions for soaking, depilation, bating and preparation for tannage, and in the treatment of hides and skins in any form hereinbefore mentioned, including tanned, dyed, fat liquored and finished 115 products of hides and skins, we have found that the addition of certain substances, unless otherwise present in the aqueous buffer solution, exert an activating effect on the carbohydrase or carbohydrases as em 120 ployed according to our invention, and hence make for the more economical and improved application of such enzymes Such activators include anions such as phosphate, citrate, formate, borate, iodide and hydro 125 sulphide ions; metallic ions such as calcium, copper, zinc and chromium ions; hydrogen peroxide; simple sugars such as galactose, dextrose and maltose; disaccharides such as sucrose; starch, yeast, bran and the various 130 values above 8 is impracticable in that stripping of tan may occur with vegetable-tanned leather and overneutralization with chromed leather Hence the quality and value of the leather may be impaired Also, we have found it impracticable to treat tanned stock with carbohydrases below a p H value of 3 in that either kind of leather may suffer damage at pl H values below 3. It is well known that unless the operation of liming is carried out carefully, a limed hide or pelt may manifest various degrees of fibre tightness Thus the butt and neck regions may be quite tight, whilst the flanks may be quite loose In the art of leather making, this phenomenon is termed irregular "loosening" or "opening up" of the fibre structure of the hide or pelt We have shown that it arises from the irregular removal of mucoid material from the hide or skin during liming This uneven distribution of mucoid material, and hence degree of tightness or "opening up" of the fibre structures, leads to irregular uptake of tans, dyestuffs and fat liquors According to the

present invention, this unevenness or irregularity in fibre structure brought about by uneven liming, can be corrected by treating the tanned stock with carbohydrases, according to the manner hereinbefore described. Tanned stock, when treated according to our invention, shows new properties in that any mucoid material remaining in association with the fibre structures is removed; thus the pelt structure becomes evenly loosened or opened up This resulting evenness of fibre structure is manifested by a regular degree of softness and suppleness over the pelt and by the even or level uptake of dyestulfs and fat liquors. It is thus seen that the treatment with carbohydrases can, at the discretion of the operator, be applied at any stage of the making of leather by existing conventional methods. Further, the operation of soaking back is a well established practice in the leather trade and consists of treating fresh or salted or dry-salted or dried or otherwise preserved :50 or cured hides and skins with aqueous liquors with the objects of ( 1) restoring the hide or skin as nearly as possible to the condition it was in after flaying, ( 2) removing the salt from salted hides and skins, and ( 3) wetting back the-fibrous structures of the hides and skins by introducing water between them The success of many of the subsequent operations in the preparation of hides and skins for tannage and other purposes depends on how well this soaking operation is carried out Many of the difficulties associated with soaking arise from the fact that the interfibrillary cement material becomes hardened around the fibres and hence makes the penetration of water 185,112 kinds of flour These substances are effectiye in concentrations ranging from 1 to 5,000 parts by weight per 100,000 parts by volume of the aforementioned buffer solua tion The simple effect of the addition of such activators is to enhance the rate of removal of mucoid material from the skin or hide. The -pelt as obtained from the treatment of hides and skins with carbohydrases, in addition to being useful for the making of leather, = can also be converted into other products Thus another object of our invention is -the production of raw-hide goods and parchments by improved methods In the prior art of making raw-hide goods and parchments from hides and skins, it is generally accepted that liming, that is, a treatment with aqueous liquors containing calcium hydroxide, is a necessary process. We have found, however, that the pelt as obtained by our invention and which does not involve the use of lime liquors, is suitable for direct conversion into raw-hide goods and parchments Fiifther, in so far as the pelt produced according to our invention is not at an

approximately constant p H value as when the liming process is used, but can be produced over the wide range of p H values 3 to 12 5, new types of pelt are now available for conversion into rawhide and parchment products. Similarly, the pelt made as described by subjecting hides and skins, or pieces of trimmings of same, to the action of carbohydrases, may be utilised for the making of gelatin and glue products It is well known that the properties of a gelatin depend on the pretreatment given to the pelt, and in the normal practice of making gelatin from hides and skins, it is usual to subject them to long periods of contact with lime liquors. Our invention does not necessarily involve the use of lime liquors and we have found that the pelt obtained by our method is rapidly and easily convertible into gelatin by the conventional methods used in gelatin manufacture -Further, since the pelt can be obtained according to our invention over the range of p values 3 to 12 5, hitherto unknown forms of gelatin now become available In accordance with our invention, hides and skins may be subjected to the combined action of both carbohydrases and proteolytic enzymes Thus in the compositions involving the use of carbohydrases, we find that the addition of proteolytic enzymes to the said compositions may be advantageous The proteolytic enzymes are added to the compositions in concentrations being within the range of O 025 % to 5 % -by weight of commercial preparation, and are to be used under exactly similar conditions as hereinbefore described for the treatment of hides 65 and skins with carbohydrases. By combined action of carbohydrases and proteolytic enzymes we mean that both these types of enzyme may be added simul-taneously at the start of the treatment of 70 the hides and skins or that the proteolytic enzyme or enzymes may be added during their treatment with carbohydrases. The use of carbohydrases to produce improvements in vegetable tanning liquors is 75 included within the scope of the invention. It is well known that myrobalans and some other vegetable tanning materials contain pectins and similar substances These are wholly or partially extracted by water with 80 the tannins and so are present in the resulting leach liquor or concentrated leach liquor, which is usually called an extract It is also known that such extracts sometimes gel and even solidify during storage We have 85 now found that this gelation and solidification can be prevented by treatment of the leach -liquor with a carbohydrase or a mixture of carbohydrases. Further, _the pectic substances are closely 90 associated or combined with the tannins. By means of our invention, it is possible to break down these large

complexes to give a liquor or extract which has modified tanning properties such as a mellower action 95 on hides or skins Furthermore, by treating vegetable tanning liquors or extracts with a carbohydrase or mixture of carbohydrases it has been found possible to modify their colours as, for example, to make them paler 100 Preferably such vegetable tanning liquors are buffered in the range p H 3-10 An improved vegetable tanning liquor for use in accordance with the invention comprises a vegetable tanning agent and one or more 105 carbohydrases in an aqueous extract buffered at p H 3-10, the concentration of the said enzyme or enzymes in the liquor being from 0.025 % to 10 % by weight of commercial preparation, said buffered extract having a 110 concentration of buffering materials of 0 25 % to 10 % by weight. The invention will now be more fully described by reference to the following Examples wherein w/v means weight/ 11 n volume, i e g /cc or Kg /litre. Ex AMP Lw I; 1- A dozenwi- salted calfskins after being soaked, washed and fleshed, were introduced into the depilating bath made up in 120 the following manner: 6,800 g sodium acetate crystals (C Ha COO Na 3 H 20) were added to 5 litres glacial acetic acid dissolved in 10 litres of water contained in a paddle, -so that a buffer solution of about p H 4 0 125 was obtained This buffer solution was diluted with water to make a total volume -of 250 litres Common salt was added to I= 785,112 container with a loosely fitted lid; the temperature being maintained at 300 C throughout the process The skins were allowed to remain in the depilating bath for 24 hours without agitation after which time the wool was loose The skins were withdrawn from the bath and pulled to obtain the wool The pelts thus obtained were suitable for liming or bating or pickling or tannage or for conversion into parchment-like products by normal trade practices. EXAMPLE 4. Six wet salted domestic woolskins were soaked for 24 hours in water, They were then transferred to the depilating bath of substantially the same composition as described in Example 1 but containing in addition 0 5 % w/v of a non-ionic wetting agent of the alkylphenylpolyglycolether type The pelts were allowed to remain in this modified depilating bath for 24 hours, the temperature being maintained at 30 C throughout the process The skins were withdrawn and pulled to obtain the wool The pelts thus obtained were suitable for the same processes as previously mentioned. give a final concentration of 1 % w/v; 500 g. calcium pyrophosphate was added to provide a source of activating calcium and pyrophosphate ions The temperature of the solution was brought to and maintained at C 2 Kg of a commercially available

pectinase preparation with bran as a carrier were added The skins were allowed to remain in this depilating bath for 36 hours when the hair was loose The skins were then withdrawn from the bath and unhaired by conventional methods The pelts thus obtained were suitable either for liming or bating or pickling or tannage, or for conversion into parchment, gelatin or glue, by normal trade practices. If in this Example the sodium acetate is replaced by 1,720 g sodium formate and the glacial acetic acid by 5,620 g of 90 % formic acid, 250 litres of a buffer solution with p H value 3, may be obtained 21 kg. of common salt may be added to give a final concentration of 1 % w/v together with 500 g calcium pyrophosphate to provide a source of activating calcium and pyrophosphate ions This buffer solution may be added to a bath containing pectinase as active ingredient. EXAMPLE 2. Twelve wet salted calfskins similarly treated were placed in a depilating bath of exactly the same composition as described in Example 1 contained in a drum The skins were drummed for 24 hours by which time the loosened hair had been removed by the mechanical action of the drum The pelts thus obtained were suitable for liming, or conversion into parchment, or gelatin, or glue, or bating, or pickling, or tannage by normal trade practices. In another experiment, twelve wet salted calfskins similarly treated were placed in a depilating bath of exactly the same composition as described above The skins were paddled for six hours after which time they were hauled out and piled, hung or folded in a warm, humid atmosphere of a temperature within the range of 15 to 35 C Any tendency to dry out was counteracted by damping the skins with the original depilating solution After 40 hours, the skins were unhaired by conventional methods. EXAMPLE 3. In another experiment, one dozen wet salted domestic woolskins were soaked for 24 hours in water and were then transferred to an aqueous bath containing 0 5 % w/v of a non-ionic wetting agent of the alkylphenylpolyglycolether type at 30 C After 2 hours contact with this wetting agent the woolskins were transferred to the depilating bath of exactly the same composition as described in Example 1 and contained in a wooden o 80 EXAMPLE 5 90 One dozen wet salted domestic woolskins were soaked in water for 24 hours They were then transferred to the modified depilating bath containing 0 5 % w/v of a nonionic wetting agent of the alkylphenylpoly 95 glycolether type in addition to the components already described The skins were allowed to remain in this depilating bath without agitation and at a temperature of C for 2 hours The skins

were then 100 in a suitable condition to be withdrawn and piled, hung, folded or painted as described in the next Example, in a humid atmosphere of temperature within the range of 15-35 C any tendency to dry out was counteracted 105 by damping the skins with the original depilating solution After 36 hours the skins were pulled and wool and pelt obtained. EXAMPLE 6 110 Wet salted domestic woolskins were soaked in water for 24 hours and then drained They were then "painted" on the flesh side with a paint consisting of 50 % by weight wheat flour, 50 % by weight pectinase 115 bran preparation mixed to a suitable consistency with an acetate/acetic acid buffer solution made in the manner described in Example 1 and containing 1 % by weight of common salt The skins were then piled 120 flesh to flesh in a humid atmosphere at a temperature of 15 to 35 C After 48 hours the skins were pulled and wool and pelt obtained. 785,1 i 2 EXAMPLE 7. 12 fully chromed calfskins, prepared by conventional methods of leather manufacture in "the blue" condition and damp, that is, in the condition immediately prior to the conventional practice of neutralisation before dyeing were introduced into a bath of exactly the same composition as that previously described in Example 1 for the depilation of calfskin The operation was carried out in a paddle, and the stock was paddled for 3 hours, the temperature being maintained at 300 C. After this loosening treatment, the skins were withdrawn and horsed up overnight. They were then dyed according to normal practice. EXAMPLE 8. 6 fully chromed calfskins were treated in exactly the same manner as described in Example 7, but after horsing up overnight were neutralised before dyeing. EXAMPLE 9. 6 calfskins chrome tanned in a manner suitable for vegetable retannage were treated in exactly the same manner as described in Example 8 After horsing up overnight, these were treated with vegetable tanning extract containing myrabolams After the completion of this combination tannage the skins were dyed according to normal practice. EXAMPLE 10. A wet salted calfskin after being soaked, washed and fleshed was introduced into a depilating bath made up in the following manner:410 g glycine and 200 g caustic soda were dissolved in a convenient amount of water so that a buffer solution of p H value about 10.4 was obtained This buffer solution was diluted with water to make a total

volume of 20 litres Common salt was added to give a final concentration of 2 % w/v Potassium iodide was added to give a final concentration of 0 5 % w/v to provide a source of activating iodide ions The temperature of the solution was maintained at 30 C. and 40 gm of the mixture of carbohydrases known as elastase were added in powder form The temperature of the solution was maintained at 30 ' C throughout the treatment and the skin was paddled continuously. The skin was allowed to remain in this depilating bath for 20 hours when the hair was loose The skin was then withdrawn from the bath and unhaired by conventional methods The pelt thus obtained was suitable either for liming or for conversion into parchment or gelatine or glue, or bating or other normal trade practices. EXAMPLE 11. A wet salted calfskin after being soaked, washed and fleshed was introduced into a depilating bath made up in the following manner: 115 g of borax and 300 g of boric acid were dissolved in a convenient amount of water so that a buffer solution of about p Hl 7 0 was obtained The buffer solution was diluted with water to make a total volume of 20 litres Common salt was. added to give a final concentration of 2 % wlv. The temperature of the solution was brought up to 30 ' C when 100 g of a commercially available powdered preparation of diastase were added. The temperature was maintained at this value throughout the treatment and the skins were paddled for 20 hours The skin was then withdrawn from the bath and unhaired by conventional methods. ( 65 s O EXAMPLE 12. Six squirrel tails in the partially tanned or tanned condition, i e as normally sup 55 plied to brush manufacturers by the fur trade, were soaked overnight in cold water. They were then placed in a depilating bath of composition exactly similar to that described in Example 1 for the depilation of 90 calfskins and contained in an open vessel of suitable size The temperature was maintained at 350 C and the treatment was allowed to proceed without agitation for 40 hours 95 The tails were then withdrawn from the bath, rinsed in water and partially dried by hydroextraction The fur from three of the squirrel tails was then pulled off in the manner normally used in the brush making 100 industry The remaining three tails were dried out completely, stored for three weeks, wet back with cold water, hydroextracted and the fur fibres pulled off in the manner hereinbefore described 105 EXAMPLE 13. A side of a sun-dried Nigerian c-owhide was placed in a soak liquor contained in an open soak pith aid of exactly similar compositi 6 ionto that described in Example 1 110. for the depilation of calfskins The temperature of the liquor was

maintained at about 250 C for 48 hours, with occasional agitation by means of a wooden pole After this treatment, the side was in a soaked 115. condition and ready for liming and subsequent operations according to conventional practices. EXAMPLE 14. A side of a sun dried Nigerian cowhide 120. was placed in a soak liquor contained in an open soak pit and of exactly similar composition to that described in Example 1: for 785,112 which treatment the hair was loose The skin was withdrawn from the bath and unhaired by conventional methods The pelt thus obtained was suitable either for liming, or for conversion into parchment or gelatine or glue or bating or other conventional treatments. EXAMPLE 18. Two fully chromed calfskins prepared by conventional methods of leather manufacture, in the "blue" and damp condition, i e. in the condition immediately prior to the conventional practice of neutralisation before dyeing were introduced into a loosening bath of the following compositions and contained in a drum. Sodium acetate crystals were added to 200 cc glacial acetic acid, dissolved in a convenient amount of water so that a buffer solution of about p'H 4 0 was obtained This buffer solution was diluted with water to make a total volume of 10 litres Common salt was added to give a final concentration of 1 % w/v. The temperature of the solution was brought to, and maintained at, 300 C 100 g. of a commercially available pectinase preparation with bran as a carrier were added together with 25 g papain The function of the papain is to aid in the dispersion and/or solution of any porteinous material loosened by the action of the pectinase The skins were drummed for 3 hours. After this treatment the skins were withdrawn and horsed up overnight They were then dyed according to normal practice. the depilation of calfskins The temperature of the liquor was maintained at about 25 C. for 48 hours with occasional agitation by means of a wooden pole After this time the hide was in a soaked condition and was then fleshed prior to depilation A further addition of pectinase-bran preparation was then added to give a total concentration of approximately 2 % w/v The temperature was then brought to 300 C and maintained there for a further 40 hours, again with occasional agitation by means of a wooden pole The side was then hauled out and depilated by a convenient method: The side was then suitable for either liming, bating or tanning by existing methods.

EXAMPLE 15. A delimed calfskin in the condition normally to be expected before "bating" by conventional methods was placed in a paddle containing a bating liquor of exactly similar composition to that described in Example 1 for the depilation of calfskins. The temperature of the liquor was maintained at 35 C for 3 hours, the skin being paddled continuously After this treatment the skin was soft and porous, in the manner of bated stock, and was ready for pickling or tanning by conventional methods. EXAMPLE 16. A dried Australian wooled sheepskin was placed in a soak liquor contained in an open soak pit and of exactly similar composition to the depilating bath described in Example 3 for the dewooling of domestic sheepskins. The temperature of this static bath was maintained at 25 " C for 18 hours The now soaked sheepskin was withdrawn and was suitable for subsequent treatment either by conventional methods or as hereinbefore described for domestic sheepskins. EXAMPLE 17. A wet salted calfskin after being soaked, washed and fleshed was introduced into a depilating bath made up in the following manner:410 g glycine and 200 g caustic soda were dissolved in a convenient amount of water so that a buffer solution of about p H 10 4 was obtained. This buffer was diluted with water to make a total volume of 20 litres. Common salt was added to give a final concentration of 2 % w/v The temperature of the solution was maintained at -30 C. g of the mixture of carbohydrases known as elastase were added together with 20 g. of trypsin The temperature of the solution was maintained at 30 C throughout the treatment and the skin was paddled continuously The skin was allowed to remain in this depilating bath for 20 hours after EXAMPLE 19. g of a commercially available bran 1 OO preparation of pectinase were extracted with 250 cc of water at 30 " C The solution of the enzyme was filtered and added to 3 litres of a myrabolams liquor of S G 1 06 Myrabolams liquor is naturally buffered in the 105. range of the present invention The resulting liquor was maintained at 30 " C for 36 hours It was then concentrated by evaporation under reduced pressure to a specific gravity of 1 2 The resulting extract was 110 allowed to stand for 3 months at temperatures ranging from 4 " C to 10 " C No gelation or solidification occurred. EXAMPLE 20. g of a commercially available bran 115 preparation of pectinase were

extracted with cc of water at 30 " C The filter solution of the enzyme was added to 200 cc of a quebracho liquor of specific gravity 1 06. Quebracho liquor is naturally buffered in 120 the range of the present invention The resulting liquor was maintained at 30 " C. for 36 hours As a control, 20 cc of water were added to 200 cc of the quebracho 785,112 liquor of specific gravity 1 06 The control liquor was also maintained at 30 ' C for 36 hours Both liquors were diluted 25 times and the colour determined with a Lovibond a Tintomreter The word Lov I Bo ND is a Regisfered Trade Mark The control gave the following figures:Reds 3 8 Yellows 6 4 The treated liquor was obviously paler than the control and gave the results:Reds 2 8 Yellows 4 5 EXAMPLE 21. Two dozen fully chromed-calf skins prepared by conventional methods of leather manufacture in "the blue" condition and damp, that is in the condition immediately prior to the conventional practice of neutralisation before dyeing are introduced into a bath made up in the following manner:2,500 g of boric acid and 32 g of caustic soda flake are dissolved in water contained in a paddle so -that a buffer solution of about p H 8 0 is obtained This buffer solution is diluted with water to make a total volume of 250,000 cc Common salt is added to give a final concentration thereof of 1 % w/v. The temperature of the solution is brought to 30 ' C 2 4 Kg of a commercially available diastase preparation are added The skins are paddled in the bath for 3 hours, the temperature being maintained at 30 ' C. After this treatment, the skins are withdrawn and horsed up overnight They are then dyed according to normal practice. In the foregoing Examples, only buffer compositions of p H values 4, 7, 8 and 10 4 have been specifically illustrated. It is clearly to be understood, however, that buffer compositions cover the range of p H values 3 to 12 5, as exemplified by: p H RANGE 3 TO 6. 5,000 parts by volume of glacial acetic acid, are diluted with water and 50 parts by weight of caustic soda flakes are added to this solution. The buffer solution of p H value 3 so made, is diluted with water to make a total volume of 250,000 parts by volume. By increasing the amount of caustic soda flakes from 50 parts by weight to 3,200 parts by weight, a buffer solution of p H value 6, is obtained Buffer solutions with p H values between 3 and 6 can be obtained by adding caustic soda flakes within the-range 50 -to 3,200 parts by weight, to the above mentioned amount of glacial acetic acid. p H RANGE 5 8 TO 8. 1,700 parts by weight of potassium dihydrogen phosphate are I

dissolved -in water and 37 parts by weight of caustic soda flakes are added to this solution The buffer solution of p H value 5 8 so made, is diluted with water to make a total volume of 250,000 parts by volume. By increasing the amount of caustic soda flakes from 37 parts by weight to 470 parts by weight, a buffer solution of p H value 8 is obtained. Buffer solutions with p H values between 5.8 and 8 can be obtained by adding caustic soda flakes within the range 37 to 470 parts by weight, to the above mentioned amount of potassium dihydrogen phosphate. p H RANGE 8 TO 94. 2,472 parts by weight of boric acid are dissolved in water and 32 parts by weight of caustic soda flakes are added to this The buffer solution of p H value 8 0 so made is diluted with water to make a total volume of 250,000 parts by volume By increasing the amount of caustic soda flake from 32 parts by weight to 250 parts by weight, a buffer solution of p H values 9 4 is obtained. Buffer solutions with p H values between 8 and 9 4 can be obtained by adding caustic soda flakes within the range 32 to 250 parts by weight, to the above mentioned amount of boric acid. p H RANGE 8 45 To 12 5. 1,500 parts by weight of glycine are dissolved in water and 50 parts by weight of caustic soda flakes are added to this solu 95 tion The buffer solution of p H value 8 45 so made, is diluted with water to make a total volume of 250,000 parts by volume. By increasing the amount of caustic soda flakes from 50 parts by weight to 2,400 parts 100 by weight a buffer solution of p H value 12 5 can be obtained Buffer solutions with p H value between 8 45 and 12 5 can be obtained by adding caustic soda flakes within the range 50 to 2,400 parts by weight to the 105 above mentioned amount of glycine Such buffer compositions may be substituted for the buffer compositions mentioned in the Examples, with equally satisfactory results, always provided, of course, that the appro l 11 priate enzyme is used In the foregoing Examples, the only activators mentioned by name consist of, sodium ions, calcium ions, pyrophosphate ions, wheat flour, iodide ions, potassium ions 115 and borate ions It is to be understood that any of the activators hereinbefore detailed, can be substituted for the activators mentioned in the Examples, with equally satisfactory results 120 In the foregoing Examples, only the carbohydrases elastase, disease and pectinase have been specifically illustrated It is to -be understood' however, that the other 785,112 wool or fur can occur, Hence the use of pectinase leads to the preparation of high quality keratinous structures. Whilst in the foregoing Examples only a non-ionic wetting agent has

been disclosed, it is to be understood that the invention will work satisfactorily with a cationic wetting agent as exemplified by cetyl pyridinium bromide, or with an anionic wetting agent as exemplified by the sodium salt of dodecyl benzene sulphonate. carbohydrases hereinbefore referred to, can also be employed with satisfactory results, always provided of course the appropriate p HI range is used. In the foregoing Examples, the proportions of carbohydrase used cover the range 0 2 % to 50 % by weight It is to be understood, however, that this range is not critical As little as 0 025 % by weight of carbohydrase can be employed effectively. The precise proportion chosen is a question of economics Similarly, in the foregoing Examples, the proportions of proteolytic enzymes cover the range 0 1 % to 0 25 % by weight but it is clearly to be understood that the concentrations of proteolytic enzyme may range from 0 025 % to 5 % by weight. Of the carbohydrases hereinbefore mentioned the use of pectinase for achieving the various objects of the invention is strongly favoured The practical advantages of using pectinase as the carbohydrase can be briefly summarised as follows:It has optimum activity at a p H value of 4.0 The development of bacteria is greatly restricted at this value and hence any bacterial damage to the hide or skin is obviated Further, in bringing about soaking, depilation, loosening and bating of the hide or skin at this p H value the pelts obtained by our invention are in an ideal condition for tannage which, according to conventional methods, is usually commenced under acid conditions and at a p H value near to 4. Thus the use of pectinase as the carbohydrase leads in practice to a reduction of the number of handling operations and hence to greater economy In the prior art hides and skins are mainly unhaired and loosened by lime liquors of p H value about 12.5 Before such limed stock can be tanned it is necessary to reduce the p H of the stock gradually by the separate operation of deliming and often complete the loosening by the further operation of bating Also, in order to bring the stock into the -correct condition for tannage a -50 pickling operation is 6 ften employed. By using pectinase as the carbohydrase at p H values about 4 these separate operations are unnecessary. A further advantage of using pectinase at p H values near 4 is that the hair, wool, fur and other keratinous structures of hides and skins can be obtained in substantially undamaged form It is well known that hair, wool, fur and other keratinous structures are easily damaged by prolonged contact with alkaline solutions. However, by bringing about depilation under the slightly acid

conditions as hereinbefore specified when using pectinase according to our invention no damage to the hair,
