429 - jramc.bmj.comjramc.bmj.com/content/jramc/45/6/429.full.pdfwhich usually absorbed 2 p.p.m. by the Horrocks test, absorbed 5 p.p.m. as bleach, and more than 6 p.p.m. as chlorine

429

FURTHER INVESTIGATION INTO THE STERILIZATION OF 'WATER BY CHLORINE AND SOME OF ITS COMPOUNDS.

By MAJOR C. H. H. HAROLD.

Royal Army Medical Corp8.

,. There is no safe method of preventing watel'·borne diseases except . sterilization of the liquirl."

-RIDEAL.

PART n.-NEW SERIES.

EPITOME OF EXPERIMENTS.

Part II.-TANK AND LABORATORY EXPERIMENTS

<continued from p. 363.)

Series N. (1) At Race's suggestion, various chlorine and ammonia combinations

were treated with certain solvents. As it was thought that the solubilities of these might be affected by varying concentration, a constant of 25 parts per million was adhered to.

20 C.c. of the solution were shaken up with ~O C.c. of CCI4, the water residue and CCI4 solution titrated ID 500 C.c. of water gave the following results ;-

UUl4 Water residue

Hypochlorous acid 0'2 08 1'0

Blea.ch Trace 1'5 1'5

Ammonium hypochlorite (made by double decom· Trace 1'5

position) 1'5

Equivalents of Cl2 a.nd NH3 0'4 1'2 1'6

Equivalent of Ci2 and! equivalent of NH3 1'3 0'2 1'5

Cl" 0 0'7

0'7

It appears that certain specific differences in solubility in CCI 4 exist. (2) Repeat using equivalents of Ob and NH3 , and an equivalent of 012

and t equivalent of NHs. Procedure as in (1), but using 50 C.c. of solution and 001 4 •

Titration in water, 300 c.c.

1 Cb + f NH3 (equivalents)

Titration in water, 300 C.c.

1 Ch + fNHs (Cb equivalent + ~ equivalent NH:<)

Titration in water 300 c,o.

CCl4 Nil

Water residue 1'5

1'5 about 50 per cent IOSB

2'5 0 2'5

0'3 0 o·::!

2'8 2'5 0'7 -~

o 2'2 2'2

0'2 3'8 4

4'2

0'2

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430 Further Investigation into the Sterilization of Water

Again similar differences appear, but in addition it is noted that a proportion of second fraction may be found both in water residue and in 0014. The mixture of equivalents provides little 0014 soluble compound.

(3) A comparison of solubility of combinations in a concentration of 25 p.p.m. All compounds left in flasks under covers on bench for four houn; to ensure stability, using '20 C.c. of solution for extraction and titration.

20 c.c. titrated in 500 c.c. water

1 Cl2 + i NHs = 1 equivalent 012 + ~ equivalent of NH

Titration in 500 c.c. water

1 Cl + ~ NH3 = equivalents

Titration in 500 c.c. water

CQmpound made by interaction of Cl2 and ammonium chloride

CCl4 Nil

Water residue 0'7 0

0'7

CS2 Water residue Nil 0'7 0

07 1'1 0 ,---

1'1

CCI4 Water residue 0 0'7 0 0'8

1'5

CS2 Water residue 0 O·g 0 0'6

15 0 1'4

1'4 0014 Water residue

0'1 0·2 O·g 0'2

-0:3 1'1 -------.---CS2

0'1 0'1 '(}2-

1'4 Water residue

1'0 0'1 -----rr-

----~----

0'9 0'4 -y.s

CCI, 0'2 1'6

-y.s-

Water residue o 0'2

-----..------~

Water residue o 0'2

--""-~-1'8

Remarks.-Note similarity of the behaviour of the last compound and the compound made from an equivalent of Oh and ~ an equivalent of NHs. On the whole the extraction of this compound is more perfect.

(4) Examination of results obtained by dosing 0'5 grm. 012 into a ll-galIon-tapk, water in tank containing 0'25 grm. NHs.

Titration, 355 c.c. against N/100 thiosulphate = 1'5 4 2'5, should be 10 p.p.m.



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O. H. H. Harold 431

What is the second fraction? 177 c.c. of water extracted with 88 COl,.

C0l4 Residue 1'3 0'5

Hs Nil

This second titration fraction is not extracted by CCI4 in this concentration.

(5) Comparison of titrations, extractions, and germicidal power. An amount of chlorine calculated to give 1 p.p.m. of Cl 2 in the tank was used for initial contact in flasks. Pollution = 25 c.c. of broth culture, 2,000 per c.c. per ll-gallon tank. For titration and extraction 20 C.c. of 25 p.p.m. solution used.

Plating, ~ hour

" 1" Titration of 20 c.c.

in 500 water Extractions

Compound made from NH,Ol + CI2

Some hundreds B. coli (best)

Negative O·g 0'6

CI2 only

Mass of growth (worst)

Hundreds B. coli 1'2' 0

1'2

Some hundreds (next best) Negative

0'5 0'7

1 Ch + ~ NHs

Some hundreds

Negative O·g 0'2

1'1

CL;}. Wa~er GUI. Water CCI. Water COl. Water residue residue residue residue

0'60'5 0 0'2 1-l" 0'2

o 0'5 0 0 0'5 0'5 0'2 0 0'1 O·g 0'2 ~~~T1

Rernarks.-As these mixtures were not allowed prolonged contact on the bench, the titration differences are not so marked.

Again, by the

This does not seem to have affected their extraction by CCI 4•

compound made from NH4Cl is extracted best, closely followed compound made by an equivalent of CI 2 and t equivalent of NHa•

From the germicidal point of view all are efficient, and there is little to choose between them.

(6) Repeat previous Experiment.

Plating, ~ hour ..

.. 1 .. Titration of tanks

after 4 hours ..

A B Compound made 1 UI + i NH3

from NH4Cl

2 cols. B. coli 1 col. B. coli

Sterile No coli 0'1 0'4 0 0'7 ----

0'5 0-7

C 1 Cl + t NHs

by making amix· ture of equivalents and tben redosing with an equivalent

of Cl, Sterile

No coli o 0'7

0'7

D 1 Cl., +! NHs

Sterile

No coli 0'4 0'2

0'6

Examination of similar solutions :-A B

20 c.c. in 500 c.C. 0'1 0'7 0'1 1'2 water titrations O'S 1'3

Extractions CC!. Water residue CUI. Water residue

o 0'6 0 0'4 o 0'6 0'1 0'7 o· 6 -----o:s-

1 1'4

D O·g 0'4

1'3

GUI. Water residue

o 0'2 ~



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Remarks.-Although no B. coli colonies appeared, some of the plates showed a mould, contamination frequently present in this water. General results similar to previous ones· '

(7) Repeat germicidal comparative tests of compounds made from NH4CI and equivalents of NH3 and C]2, and an equivalent of C]~ and half an equivalent of NH3• An estimated 1 p.p.m. C]2 dosed into flasks for contact prior to pouring into ll-gallon tanks. '

,Indicators, 25 C.c. of watery suspension of 2,000 million per c.c. in each tank.

Platingsi hour

Compound from NH.Cl.

~ " Titrations-

1 Ul2 +! NH3

Some thousands About 1,000 0'1 0'75

O'Sb p.p.m.

1 Cl. + ~ NH8

Same as previous plate About 200

0'6 0'25

Best, about 200 Best, about 150 cols.

0'1 0'5 ~ hour 0'85 p.p.m. 0'6 p.p.m.

Action delayed by low temperature of water, 4° C: A very excellent result when the enormous dose of organisms is considered; little to choose between these bodies. Equivalents superior to 1 Cl + i NH3.

(8) Chloramines made by Race's method by interaction of bleach and NH3 and using his concentrations. Dosed into 2-litre flasks to give concentration of 25 p.p.m. in accordance with previous experiments, using 20 c.c. for extraction with COI4•

CCl, Water residue trace, 1'1 0'1

less than 0'1 1'2 ---:-1'-0--

Dosed into ll-gallon tank should give 1 p.p.m. 0'7 0'2

Titration of 355 c.c. against N/lOO thiosulphate = -----,,-O.-:-:\j-

Remarks.-Typical equivalents.

titration and extraction given by mixture of

Now using half the amount of NH3 =' 1 01 + -1 NHs, 20 c.c. per extraction.

CCl,

o 0'2 0-'2-

(1) Water residue

0'8 0'3 1'1

---;-1--;;·3,.----

Dosed into ll.gailon tank. Titration of 355 C.c. with

N/lOO thiosulphate solution 0'7 0'2

U'\j

(2) Repeated, allowing longer contact

between bleach and ammonia solution COl, Water residue

o 0'1 0'4 0'6 0'1 1

---=1--=·1:-----

Dosed into ll-gallon tank. Titration of 355 c.c. with

N/100 thiosulphate solution 03 0'5

0'8

Remarks.-Results with equivalents very similar to those obtained with NHs and C1 2 , but results with an equivalent of Cl 2 as bleach and t an equivalent of NH3 not so definite. If longer contact is permitted, there is a definite increase in the second fraction, but solubility of this in 0014 is



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O. H. H. Harold 433

poor. Is this due to imperfect combination or due to effect. of base Ca ? In any case, behaviour of mixture of equivalents is similar to compound made by us. The germicidal powers are also similar.

Series O.

When testing these compounds against River Lee water at Middlesex Wharf, in company with Major Elliott, O.B.E., D.Sc., etc., Instructor in Chemistry, Royal Army Medical College, it was found that this water which usually absorbed 2 p.p.m. by the Horrocks test, absorbed 5 p.p.m. as bleach, and more than 6 p.p.m. as chlorine. This was unusual, and the difference bet.ween the absorption of hypochlorite and Cl 2 was inexplicable. Samples of this water examined later on two occasions as below :-

Sample 1, showed NH3, F and S Nitrites

Sample 2, taken after rain, October 7, showed NH3, F and S Nitrites

11'0 p.p.m. 2'0

3'28 0'16 "

Doing comparative Horrocks tests, using (a) 012, (b) bleach solution, (c) combinations of equivalents of NH3 and Cb, (d) combination of 2 equivalents of Cb to 1 of NH3 •

Readings-Chlorine gas 3rd cup Bleach. . 2nd " Equivalents of NH3 and Cl2 1st " 2 of 012 to 1 of NH3 1st "

Remarks.-Previous subsidiary tests had shown that although Cl2

behaved regularly in· regard to absorption in presence of nitrites, bypochlorite (bleach) did not. This is apparent from the above, The resistance of chlorine ammonia compounds to absorption is of interest, It appeared that further investigation was desirable.

(2) The effects of increasing amounts of NH3 in water upon germicidal velocity, titration results, bleaching powers, etc., in ll-gallon tanks, all dosed with 0'05 grm. of Cb = 1 p.p.m. NH3 mixed in water first. Comparative weights shown.

Indicators, 1 C.c. of watery suspension B. coli = 2,000 million per c.c. per tank.

Cl2 Cl2+ Cb + Cl2 + Cl2 + alone ~NH3 1 NH3 2 NH3 4 NH3

Platings-5 minutes" Large 2 cols, Large Mass of Mass of

growth growth growth growth 10

" Some 1 col.

" " reduction 20

" 1 "

Titrations 0'3 0'1 O'S 0'1 0'7 0'2 0'5 0'3 0'4 0'5

0'4 O'g O'g 0'8 O'g After 24 hours, , 0 0'5 0'05 0'6 0'05 0'6 0'15 0'3 0'5

0'55 0'65 0'75 0'8

28



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434 F'ltrther Investigation into the Sterilization of Water

It was demonstrated that although 250 c.c. water from Cb tank, containing only 0'4 p.p.m. available C12, possessed considerable bleaching properties. against dilute dye, in all tanks containing NHs bleaching had practically ceased. After prolonged contact the chlorinated ammonized water bleached 0'3 C.c. of dye in the presence of acid.

A ttempts at extraction of the compound in the tank showing the large second fraction, showed that the second fraction compound could not be extracted .. This second fraction is seen to increase with the amount of NHs present and is attributed to action of excess base. The conservative action of NH3 upon available chlorine is well shown, also the retardation of germicidal velocity by excess of ammonia. The results obtained originally in the flasks receive confirmation.

(3) Effect of adding chlorine and various compounds having an estiLllated concentration of 1 p.p.m. to tank containing excess of ammonia.

Contained in water: .p.m. H 0'4 0-2

0'6 Ch added. Titration

0'6 0'2 O'S

Ammonium hypochlorite made by double decomposition =

Bleach solution 0'4 0'1 0'5

4 p.p.m. NHs in tanks

Bleach solution .. 0'2 0'6 O'S

Remarks.-Again there is a change in the bleach titration caused by increasing the NHs. N.B.-Also vide experiments quoted in text of paper.

(4) The effect of excess ammonia on titration. 'Compounds made by mixing equivalents of NHs and Cl2 in l,lsual manner and dosed into water containing 10 p.p.m. NHs.

Titration, 355 c.c. N/lOO thiosulphate solution. 0'2 0'5 0'35 0'35

i hour, 0'7 1 hour, 0'7 o

24 hours,

Same concentration of NHs in water, using pourmg technique as performed in regimental water-cart.

0'3 0-45 0'3 0-45 0 0'6 i hour, 0'75 hour, 0'75 ; 24 hours ~

Attempts at extraction of this body with solvents showed it present in watery residue only. Hence it appears that excess of ammonia may modify these titration results although solubility may also be affected by differences in concentration.

Previous experiments demonstrated that titration results of both Cl2

solution and chlorine ammonia compounds can be modified by presence of excess NHs in water. The following demonstrates the effect upon germicidal power. Broth culture 25 c.c. per ll-gallon tank.



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O. H. H. Harold 435

1 Cl2 + ~ NHs (given initial contact in 2-litre flask)

Water containing: 2 p.p.m. NHs 4 p,p.m. Plating, ~ hour About 100 Some hundreds

1" Negative Negative

1~ " Titration, ~ hour 0'4 0'2 0'4 0·25

0'6 0'65

1~ 0'4 0'25 0'5 0·15

" 0'65 0'65

012 only.

2p.p.m. Film of growth

About 100 Negative 0'5 0'2

0'7 0'5 0'2

0'7

4p.p.m. Film of growth

53 cols. Negative

0'45 0'3 0'75

0'45 0'2 0'65

Remarks.-Excess NHs has resulted in the production of second titration fraction with chlorine. This combination is not as effective as the compounds formed by the interaction of equivalents in ideal concentration. Horrocks Test Results.

Ab.ove ordinary water, with 012

" " " bleach " tanks, containing 2 NHs and broth

012 .. Bleach

containing 4 NHs and broth Bleach 012 ..

'= 2nd cup = 2nd cup

= nearly 1st cup (2nd cup) = 1st cup

= 1st cup = 1st cup, but a little absorp

tion not as deep as bleach

Remarks.-It appears that bleach and Cl2 do not react equally III

presence of NHs, bleach being more readily affected.

Series P.

Having obtained certain information regarding the behaviour of chlorine and some of its compounds in the presence of NHs, it appeared desirable to investigate the effect of the presence of both NHs and N02•

At first it was impossible to obtain waters containing suitable quantities of NHs and N02 • It appeared that standard silver nitrate, although behaving in a regular manner with C1 2, reacted in an irregular manner, and som,etimes not at all, with bleach.

As ammonium nitrite should be commonly present in waters containing ammonia and NOz, this compound was prepared by the interaction of Ba(N02h and (NH4hS04 and proved satisfactory. In regard to indicators, it was realized that trouble would arise in the presence of N02• 'An attempt to get over this difficulty was made by employing O-tolidin, which is stated to be superior to starch and RI in the presence of nitrites. It was found to be an excellent indicator from the point of view of making a rapid estimation of Cb against standards, but it was also affected by the large amount of N02 used and offered little advantage. It is 'true in certain instances when both Cb and N02 had been used up by interaction O-tolidin gave lighter tints, but our usual indicator, starch and RI did likewise.



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436 F'urther Investigation into the Sterilization of Water

(1) Horrocks test

Cl2

Bleach Chlorine ammonia com

pounds made by con: tact of equivalents of NHs and C12

Plain 'water and nitrite 1 p.p.m.

3rd cup 1st cup 1st cup

Nitrite 1 p.p.m. and 2 p.p. m. NHs

2nd cup 1st cup 1st cup

Nitrite 1 p.p.m. and 4 p.p.m. NHs

2nd cup 1st cup 1st cup

Remarks.-An attempt at titration with acid was made, but a mixed chlorine second fraction and nitrite fraction appeared, and no reading could be obtained. It shows that the Cl2 readillg is modified in the presence of excess ammonia. Chlorine ammonia compounds are unaffected.

(2) Repeat with Bourley water with 0'125 N0 2 per million-it being found that the above standard nitrite was not dependable.

Bleach Chlorine ammonia com

pounds made by initial contact of equivalents of Cl2 and NHs

0'125 NO. in water 2nd cup

2nd cup 1st cup

0'125 NO, and 2~p.p.m. NHs

1st cup (little absorption)

1st cup 1st cup

0'125 NO. and 4 p.p.m. NHs

1st cup

1st cup 1st cup

Remarks.-Chlorine ammonia compounds still unaffected. '1'he action of NE 3 on CI 2 and hypochlorite is represented.

(3) Horrocks Test-plain water with Cl2 only = second cup.

Water containing:

Cl. Bleach

(Cl-. and ~ NHs compound)' (Or;: and i NHs compound)1

2 p.p.m. NO.

5th cup 2nd cup 1st cup 1st cup

(comes up very, very slowly)

2 NO. and 2 p.p.m. NHs

2nd cup 1st cup 1st cup 1st cup

1 These compounds formed by initial contact in flasks.

2 p.p.m. NO. and 4 p.p.m. NB.

1st cup 1st cup 1st cup 1st cup

Remarks.-Chlorine ammonia compounds, when properly formed in this way, are unaffected. The blocking of oxidation by NE3 is demonstrated, and the unequal reaction of Cl2 and bleach.

(4) It is shown above that the blue colour with RI and starch when using an equivalent of Cl2 and j equivalent of NH3 only develops after prolonged standing. May this not be nitrite?

Acid usually assists the development of a good nitrite reaction with starch and RI. An attempt was made to titrate out N02 from C12•

Into all tanks solution of Cl2 to give 1 p.p.m. was dosed. In the case of chlorine ammonia compotinds,.mixtures of equivalents of Cl 2 and NHs and t an equivalent of NH3 and 1 of CI 2 were given initial contact in flasks. The dose of available Cb in these should lie between 0'6 and 1 p.p.m.



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O. H. H. Harold 437

Tanks containing: A

Nitrite only 2p.p.m.

Added to above:

B

NO. 2 p.p.m. NH32p.p.m.

C NO.2p.p.m. NH3 4 p.p.m.

D

NO.2p.p.m. NH32p.p.m.

E NO.2p.p.m. NH34 p.p.m.

1 Cl. :I NHs Cl. 1 p.p.m. Cl. 1 p.p.m. 1 Cl 2 ~ NH3 1 Cl, ~ NH" compound compound compound

Titrating 355 c.c. against N/100 thiosulphate:

o + mixture of 1'0'5 + mixture of I 0'7 + mixture of 10 '5 + mixture of 10'5 + mixture of 2nd fraction and 2nd fraction and 2nd fraction and 2nd fraction and 2nd fraction and nitrites I nitrites' nitrites nitrites nitrites.

Bemarks.-This titration was carried out expeditiously, so that without prolonged standing no colour appeared in A on the addition of starch and KI. The only way by which it can be proved that the compound in A is not markedly affected by N02 is by an examInation of the germicidal powers. Chlorine and the compound formed by interaction of equivalents of NH3 and Ch show the presence of an excellent first fraction of available 012 , It' is not possible to distinguish a second titration fraction from nitrite.

(5) To verify the previous deductions the following experiments were performed.

Water in tanks containing 25 c.c. broth culture 1,000 million B. coli per c.c.,a huge load of pollution, all contain 0'125 p.p.m. of N02 and varying quantities of NH3. Into these chlorine and ammonia compounds were dosed. Tanks containing:

~ hour plating

1 " Titration

0·125 N02 p.p.m. and 2 p.p.m. NH3.

A B C12 1 p.p.m.

an enormous heavy film Light film

0'4 0'2 0'6

1 Cl ~ NH3 compound Film light

Cols. 110

0'125 N02 and 4p.p.m. NH3.

C D Cl2 1 p.p.m. 1 Cl ~ NHs

Very heavy film

Light film (better than A)

0-3 0-5 0-7

compound Very heavy

film Cols. some hundreds 0'2 0'5

0-7

Remarks.-Again the superiority of these compounds is shown in the presence of excess ammonia. The amount of N02 present being small a second titration fraction can _ be obtained, the blocking action by the relatively large amount of NH3 present being effective. To get better information, further tests must be carried out, using larger amounts of N0 2 • Note the increased second fraction titration in the' presence cif the larger quantities of NH3.

(6) Amount of chlorine used to make compounds in each case represents a theoretical 1 p.p.m. in tanks. Indicators, 2000 million B. colio in watery suspension. Comparative results obtained in ll-gallon tanks containing varying quantities of NH3 and N02•



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A = N02 2 p.p.m. in water into which was dosed

B = N02 2 p.p.m. o = N02 2 p.p.m.

D = N02 2 p.p.m.

" "

" E = N02, NH3 each 2 p.p.m.

" "

F = N02 2 p.p.m. NHs 4 p.p.m. "

Plating- A B 20 minutes .. 3 cols. 6 cols. 40

" Negative Negative

1 hour " "

Titrations 0'2+N02 0'5+N02 and . and

2nd fracto 2nd fracto

"

" o

No cols. Negative

0'4+N02 and

2nd fracto

a compound made by' interaction of 1 equivalent of Oh and ~ equivalent of NHs = (1012 + i NH3 by weight) equivalents of 012 and NHs (1 + ~).

equivalents of 012 and NHs made (1 + ~) from ammon. carbo equivalents of 012 and NHs made by (1 + ~) by pouring methods. equivalents of 012 and NHs made in (1 + ~) usual way. equivalents of 012 and NH3 made in (1 + ~) usual way.

D E 27 cols. 52 cols.

1 col. Negative

0'2+N02 and

2nd fracto

10 " 1 col.

0'4+N02 and

2nd fracto

F Over 100 cols.

61 cols.

33 "

0'3+N02 and

2nd fracto

Remarks.-These compounds do withstand the action of N02• It is impossible to titrate out the second chlorine fraction on account of the nitrite reaction. The restraining action of NH3 on germicidal velocity ap~ears.

Series Q. (1) The manufacture of a compound behaving in regard to its titration

in water, its solubility in CC14 and CS4 and germicidal activity, like the compound made from two equivalents of Cl and one of ammonia.

Varying quantities of NH4Cl placed in strong chlorine solution in stoppered bottles, using quantities of Cb = 0'5 grm. and NH4CI solution =15 per cent. Hence 10 C.c. of NH4CI solution contains 1'5 grm. of NH4Cl, and of this NH4 radicle = roughly 0'5 grm.and Cb = 1 grm.

Strength of Cb solution = 0'7 per ,cent. Bottles containing 0'5 grm. Cb in 71 C.C.

NH401 15 per cent

A

2'5 C.C. = 0'125 grin. NH3

radicle

B

5 C.C. = 0'25 grm. NHs

radicle

C 10 C.C. =

0'5 grm. NHs radicle

D

2.0 c,c, = 1 grm. NHs

radicle

Leave half an hour and solution becomes white. Pungent acrid smell and on shaking very fine bubbles of gas. (Take care of eyes as bubbles break off from the surface and are very irritating.)

KI dissolved in 200 c.c. water, 0'40 C.C. from each bottle IS then added in turn.

Titration with NllO thio. sulphate

.0'4 C.C. into 500 C.C. of tap· water

'After 1 hour, 5 c.c. dosed into KI, and titrated against NIIO thiosulphate

After 12 hours

0'1

A

0'5

0'55 0'65

5'3

1'7

B 0'5

0 0'6 Q-6

5

1'9

C D 0'4 0'4

0 0'6 0 0'5 ~ -0'5-

5 4'9 gassing gassing freely

N2 N2



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O. H. H. Harold 439

Poor bleaching properties. Also vide first fraction in water. Best results, with 5 c.c., and 10 C.c. NH4Cl. Amount produced = 50 per cent of available Cl 2 or 3;600 p.p.m. Larger

ratios of NH4Cl lead to loss by excessive formation of HCl and evolution of N .

(2) Repeat exactly the same, using 0'5 grm. 01 2, Strength Cl2

151 C.c. = 0'5 grm. A B o

NH.Cl 15 per cent •• 2'5 C.c. 5 C.c. 10 c.c. After 1 hour, 1 c.c. added to KI solution.

0'5 c c 0'25 0'2 0'25 0'15 Titration, N/10 thiosulphate .. 0'45 0'4

After ~ hour, 0'1 c.c. in 500 c.c. of tap.water.

N/lOO thiosulphate 0'05 0'30 0'1 0'3 0'35 0'4

After it hour, 1 c.c. to KI solution.

" 0'20 0'25 0'2 0'2

0'45 --:0"·4--,------:-N/lO thiosulphate

D 20 c.c.

0'15 0'35 0'5

0'25 0'2 0'45

0'2 0'25 --0-45-

(gassing freely) N 2

0'1 C.c. to 500 C.c. H 2 0. N/lOO thiosulphate

1 hour, 10 c.c. into KI solution arid acid

o 0'3 o 0'4 0 0'3 -""""0-"4- 0'3

3'8 4'3

12 hOUTS, N/I0 thiosulphate •. 2 C.c. 1'5 c.c. 1 c.c.

Poor bleaching powers. Note that the complete second fraction does not become apparent until the compound is in extremely dilute solution. Note loss after twelve hours' exposure. .

(3) Ranging downwards, as above. 10'5 grm. Cl2 used. A B

NH.Cl 15 % C D E

Cl ,only 0'25 c.c. 0'5 c.c. 0'75 c.c. 1 C.c.

After ~ hour add to 2.litre flasks = approx. 250 p.p.m. of Cl.

Titration: 20 c.c. in 500 C.c. 9'9 H 2 0 N/100 thiosul-

phate

o 6'5 1 7'1

Extraction: of 20 CCl4 Water CCl4 Water CCl4 C.C. with CCl4 residue residue

3 0 4'1 0 3 0'3 1 0 4 0'5

7 7 1 -8-

Water OCl4 Water OC14 Water residue residue residue 0'1 0 4'4 1'7 0'1 0 4 1'8 0

0'1 ~ o-l~

Remm·ks.-This IS an extremely interesting experiment to interpret It has been observ,ed that Cb is extracted by CC14 from strong aqueou solution. In concentrations of 25 parts per million it behaves like HClO and is not extracted. Here in a concentration of 250 parts per million it is partially extracted, at the same time a considerable loss occurs. Even with the lowest concentration of NH4CI = 0'25 C.c. = 0'0375 of ammonium chloride = 0'0125 of NHa radicle, a second titration figure begins, to appear and concurrently a fall in the available Cb figure is



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440 FUTther Investigation into the Sterilization of Water

observed. With increasing amounts of NH4Cl the fraction of available Cb left in the watery residue becomes steadily smaller, until with 1 c.c. of NH4Cl the whole of. the available chlorine is abstracted from aqueous solution.

The above solutions vary in colour, from the yeJIow of the chlorine control to dead white when using 1 c.c. of NH4Cl. The solution B has certain bleaching properties, and with increasing quantities of NH4Cl in C, D and E, this power diminishes" From the titration figures the largest second fractions appear with 1 C.c. of NH4CI = 0'15 grm., viz., 1'8, and is completely extracted byCC14 •

During these experiments, and the experiments using diffusers, two types of gas bubbles were observed-extremely fine ones, which become more apparent on shaking, and coarse ones. The former are chloramines and the latter nitrogen, a sure index of excess ammonia. Tbe evolution of N2 is accompanied by excessive loss of available C1 2• It should be realized that the rapidity of this reaction is largely dependent upon the dilution of the reagents and the temperature, and when this approximates to freezing point the reaction may remain imperfect or take hours to complete. If other ammonium salts, NH4NOs, (NH4hS04, are used in appropriate quantities, baving due regard to the relative NH4 content, similar results can he obtained. Tbe germicidal powers, etc., of this compound have already been described.

Series R.-The Ammonium Carbonate Tablet.

Ammonium carbonate on exposure to air gives off ammonia and becomes ammonium hydrogen carbonate.

(NB.l 2 CO. = B(NB.)CO. + NB. (NB.) co. = 36 + 60 = 96 = 37 per cent NB,

therefore 0'25 grm. of NHs = 0'66 grm. of (NH4)COs = an equivalent of 0'5 grm. of C12•

Old (NH4)2COS may have an available NHs content of 18 per cent, equals 50 per cent loss. If the amount of ammonia entering into combination with 0'5 grm. of Cb is 0'125 grm. instead of 0'25 grm., the second fraction chloramine is formed. When amounts of NHs short cif 0'5 grm. are used (a double equivalent) the first fraction chloramine is produced. Hence when using NHs we have a margin of safety on each side of the optimum, 0'25 grm., up to 0'5 grm. and down to 0'125 grm.

If ammonium carbonate is exposed for some time two types of deterioration may be anticipated: (1) An actual loss of weight by Yolatilization, (2) loss of NHs content by gradual conversion into hydrogen ammonium carbonate.

Provided the tablets are packed in small quantities tbe first type of deterioration is of little importance, but the second requires particular attention .. To safeguard ourselves against tbese contingencies, a tablet of



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O. H. H. Harold 441

ammon. carbo weighing 1 grm. is suggested. Should this not prove satisfactory it may be necessary to specify hydrogen ammonium carbonate instead of normal carbonate.

If the ammonium carbonate is up to full strength it is within the upward range of safety of two equivalents (1'32 grm.). If it is old it will still contain 0'135 g~m. of NH4 which is within the lower margin for the production of the second fraction chloramine. Under average conditions the tablet should contain NHs slightly in excess of 0':25 grm., which is the estimated optimum.

Series S.

The formation of chloramines by the interaction of simple solutions without appreciable loss of available Cb is not in conformation with the following equation :-

NH,OH + C12 = NH2Cl + HCl + H 20

To account for these results certain theories which appear to have a reasonable basis have been advanced in the Section "Significance of Foregoing Remarks."

Evidenc.e has been adduced, particularly in New Series F) Experiment 5; Series J, Experiments 2 and 4; Series L, Experiment 1; Series M, Experiments 2, 3, 4; Series N, that two compounds are formed endowed with considerable germicidal powers: (1) by a combination of equivalents of Cb and NHs; (2) by interaction of two equivalents of CI2 with one of NHs and that the former can be changed to the latter by the addition of an equivalent of Cb. If further additions of Cb are made compounds containing higher ratios of Cb are not formed under these conditions, and the Cb remains as free C12•

In support of the foregoing, the possibility arises that further proof may be afforded by conductivity tests, in which a marked rise in the conductivity figure would be indicative of HCI formation.

The water used for these tests had an initial conductivity of 5 reciprocal megohms, and although not ideal was of sufficiently good quality to ensure reasonable results.

C12

in grm. per 2 litres

0'05 0'05

0'05 Hydrochloric acid 0'05 Ammon. chloride 0·075

NHs in grm. per 2 litres

0'025

0'025 0·0125 0'0125

Conductivity in reciprocal megohms

5 35

100 70 27

50 (repeat) 46 260 95

Remarks.-Note the marked differences between the conductivity of solutions of Cl2 and C12 + NHs combinations. There is no marked rise due to formation of ionized HCI.



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Cl2 NHs Conductivity in grm. per 2 litres iu grm. per 2 litres in reciprocal megohms

5 0'05 47

0'1 255 0'1 0'05 130 0'2 490 0'2 0'05 295 0'3 0'05 540

HCl' 0'1 515 Ammon. chloride 0'15 195

1 Note that the addition of an equivalent of Cl2 to a solution containing two equivalents of Cb and one of NHs leads to a marked rise in the conductivity. If this were due to free Cb the increase should be some,thing below 255 megohms, and it is 245 megohms. There is no 'evidence pointing to HCl formation.

Remarks.-Regarding the reactions which take place between ammonium chloride and chlorine solutions, Experiment 3, Series Q, indicates that when the chlorine and ammonium chloride solutions are correctly adjusted one stage may be represented thus:-

NH4Cl + 2 C12 = NHCI. + 3 HC!.

In the hands of Dr. E. B. Higgins quantitative estimations of HCI formation are confirmatory.

In the performance of the conductivity tests I am Indebted to Messrs. United Water Softeners, Ltd., for the use of apparatus and their Research Laboratories at Brent~ord, and for the collaboration of their technical staff under the direction of Dr. R B. Higgins.

Series T.

Numerous confirmatory experiments, and especially those connected with the bleaching, have been omitted.

The production of chloramines by means of diffusers has not been described, as most of the points regarding this method are covered by the foregoing experiments.

The methods described in this paper are covered by Provisional Patents (with War Office approval), and are being independently investigated by water experts. I wish to acknowledge the facilities afforded me by Colonel A. H. Safford, Officer Commanding the Army School of Hygiene, the assistance of Captain McKibbin and Serjeant Mace, R.A.M.C., who were responsible for the majority of standard solutions used, and Private Bowness, upon whom fell the brunt of work connected with media making and sterilization.



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Documents

429 - jramc.bmj.comjramc.bmj.com/content/jramc/45/6/429.full.pdfwhich usually absorbed 2 p.p.m. by the Horrocks test, absorbed 5 p.p.m. as bleach, and more than 6 p.p.m. as chlorine