THE STERILIZATION OF WATER BY CHLORINE AND HYPO-CHLORITES.

By V. NESFIELD, f.b.c.s.,

MAJOR, I.M.S.

In Public Health, July 1903, I described what was at the time a complete novelty, the steriliza- tion of drinking water by chlorine; indeed, the sterilization of water by any means other than heat or filtration had scarcely been considered a possibility.

It was the colossal epidemic of typhoid during the South African War that caused me to take up

what appeared at the time an all-important research, viz., the sterilization of drinking water by some simple means applicable to an army in the field.

To quote from an article by "

Lens," entitled "The Conquest of Typhoid Fever," in the Neiv

Statesman, November 18th, 1916: "Typhoid fever has been for unknown ages one of the chief slayers of mankind. Above all it has been the enemy of soldiers, all soldieis?in nil times, everywhere?of whom it has doubtless killed far more than all other agents, military or

pathogenic, if not more than all such put together

"Thanks to Edwin Chad wick and his successors, we have in this country the finest system of

primary sanitation in the world, and our cities

scarcely know typhoid fever. But in war all this is left behind.

"During the South African "War we endured 57,000 cases of typhoid fever, with 8,000 deaths. Twelve hundred bodies of British soldiers killed by this bacillus lie in one cemetery outside Bloemfontein alone."

It was not long before it was obvious that

boiling or filtration in any form was impracti- cable, and hence I turned to chemistry, and by a process of exclusion arrived at chlorine in 1901

as the only possible chemical for military purposes and early in 1902 iodine as an

alternative. Sir Aim roth Wright and Major P. G. Easton,

r.a.M.C., will remember my work in this direction

at St. Mary's Hospital, London, whilst resident

there. Colonel Willcox, A.M.S., Consulting Physi- cian, Mesopotamia, urged me to write my first

article on the subject in July 1903. At the time I was under the impression that

chemical sterilization of water by any means was an innovation. But Dr. Samuel Rideal about

1901 had brought out the acid sulphate of soda

process, and about the same time Dr. Hankin in India was advocating permanganate of potash, and Surgeon-General Shumberg, bromine in

America. In November 1902, Vaillard described iodine

for this purpose in a French journal. At the

time also I was actually using it, and obtained British patents for it for a firm who wished to

take up the process. It was actually first put in practice in the Tibet Expedition, 1904, and has since been largely used.

I only knew of Vaillard's work in 1906, and that our work was independent was shown by the fact that I used one-sixth the quantity of iodine that he did.

Since then another oxidizing substance, ozone, has been strongly recommended and used in

municipal installations. So much for the early history of chlorine and

iodine for water sterilization.

352 THE INDIAN MEDICAL GAZETTE. [Oct., 1917.

The form in which I originally put forward chlorine was the liquid gas in steel cylinders for

large quantities, and bleaching powder for smaller quantities. The water was dechlorinated with

sulphite of soda, and later with hypo-sulphite. I wrote on the subject very frequently in the

journals, and gave many demonstrations, and

approached the Army Headquarters authorities in India almost yearly, but with no success, mostly, I think, because the subject was so

vastly simple. The one -point to recognise is that, if free

chlorine ('nascent oxygen) or iodine can be shown to exist in water by the potassium iodide and starch test, the ivater is sterile. The proper appreciation of this law removes all doubts as to

dosage and sterility. In 1909-10, Professor R. T. Hewlett* took

up the subject and showed that 0'25 part of chlorine per 1,000,000 parts of water sterilized it. I cannot do better than to add to this evidence by quoting from the Journal of the Royal Sanitary Institute, Vol. XXXI, Xo. 8, 30th September, 1910:?

The Sterilization of Water by Chlorine, by Professor G-. Sims Woodhead, m.a., m.d., LL.D. ("FELLOW), READ AT CAMBRIDGE, 1 GTH

July, 1910.

For nearly a year we worked in my laboratory with small quantities of water containing com-

paratively large numbers of bacilli (B. coli) with and without additional organic matter (in the form of meat peptone broth), and it was

found that even large numbers of bacilli (several hundred per c.c. of water), could be rendered inactive by three parts of chlorinated lime in 2,000,000 parts of water, i.e., one part of avail- able chlorine in 2,000,000 parts of water.

Having thus obtained a basis for further opera- tions, it was deemed expedient to carry out an

experiment on a large scale. #"'###

It was evident, however, that as some chlorine

always remained to be neutralised, the limit of dilution that would still be efficient had not yet been reached, and the installation was run for a couple of days so as to introduce one part of chlorine into between 7,000,000 and 8,000,000 parts of water. Here the excess of chlorine unabsorbed was so slight that neutralisation by bi-sulphite was not necessary. There was neither taste nor smell of chlorine left in the treated water an hour after it was taken at the weir, but the destruction of the non-sporing organisms was complete.

Of 13 samples of 500 c.c. each taken during this series when one "part of available chlorine was added to betiueen 7 and 8 million parts of

water, every one was sterile, no coli-form organisms being found in (H litres of the water treated. Moreover, on no single occasion was there either a taste or smell of chlorine in the

water, which was bright and very fresh and

palatable. It is evident then that the sterilization of

Cambridge water by bleaching powder is not only efficient, but is easily carried out, for when there is the faintest chlorine reaction in the treated ivater as it comes from the chlorinating cylinder {after being in contact with the chlorine for at least 20 minutes), sterilization is complete. The amount of chlorine remaining at the end

of the period of contact may be measured very readily by any intelligent labourer supplied with

a bottle of iodide of potassium crystals, a flask of filtered starch, and a little weak acetic acid.

If a blue tint, especially a deep blue, appears, too much clorine is being added. A violent tint is the proper end reaction, showing the presence of a trace of chlorine, whilst if no colour reaction be obtained, the amount of chlorine present is

probably not sufficient to ensure sterilization. When large quantities of organic matter are

present or held in solution, there is an unpleasant flavour. These taste-giving substances which

appear to be related to the amines, chloramines, etc., require further study.

Discussion.

Dr. J. C. Thresh said that he was consulted by the Candy Filter Company for a water resembling in all respects that of the Thames at the intake of the Metropolitan water board. The river water which originally contained

thousands of bacteria per c.c. and B. coli

generally in O'l c.c. and sometimes in 0*01 c.c.

had all the objectionable bacteria removed by one part of chlorine in 2,000,000 parts of water. The taste of chloramines could be removed by previous filtration.

Chlorine in the small quantity used had not the slightest action upon metals, fittings, etc.

# # #

I shall also quote from an article by Major C. R. Durnall, m.d. (Medical Corps, United States Army), in the Journal of the American Public Health Association, November 1911:

In June 1910, the writer began a series of

experiments with the object of determining the

availability of commercial liquefied chlorine gas for the purification of water. It is believed that

the use of chlorine in the gaseous form and dry state had not been used or proposed for the puri- fication of domestic water supplies before that time.

# # ? ??

Dry chlorine can be kept in steel drums indefi- nitely and may be conducted through iron, brass, and copper pipes and valves without undue

corrosion. Hewlett's Bacteriology.

Oct., 1917.] THE STERILIZATION OF WATER, 353

In general it may be said that with an average unfiltered river water sucli as that of the Potomac, about 1 in 2,000,000 parts of chlorine are

required. For clear lake waters 1 in 3,300,000

parts of chlorine will be sufficient, i.e., it will

require from 3 to 4 pounds of liquid chlorine for

a million gallons of water of average purity. * # * *

Length of time of contact.?The experiments made in the chemical laboratory of the army

medical school indicate that the purifying action of chlorine gas, when applied to Potomac river

water, is practically instantaneous. If particulate matter in which bacteria are embedded is in the

water, the action of the chlorine is not so rapid, time beino- required for it to penetrate the particles. ** * *

Again it will be observed that 0*5 of a part of

chlorine per million was quite as effective as

larger quantities. The surviving bacteria were chiefly bacillus

subtlis (the hay bacillus). Dr. S. Rideal said, it would seem therefore

that it must be the duty of the water authorities to ensure the absence of B. coli from the water

supply as far as possible, and there could be no

doubt that, if by such a standard was meant the

absence of B. coli from several hundred c.c. of

the water, such a result could only be economi-

cally obtained by sterilizing processes after the

ordinary methods of filtration. Maine water at

Paris was sterilized by 1 to 2 parts per million of

available chlorine. The results obtained by the use of chlorine in American and Canadian cities

are summarised from details given in the Sur-

vey er, 10th June 1910.

Place.

Har r i s b urg, P. A.

Hartford,Conn Jersey City,

N. J. Minnea pol is, Min

Mo n t r e a 1, Canada

Nash Ville, Tenn

Quincey, 111.

Toronto,Cana- da

2 a u

23 T5

0

July 1909

Jany. 1909 110,000,000

Feby. 1910 .20,000,000

Jany. 1910 140,000,000

Aug. 1909 114,000,000 A pi. 1909 I

?-> x.

March 1910 35,000,000

0-39

1

0-2

11

0*35

0-45 1-1 to 0'4;i

o-ii

Z <D

.2 o

Q) &

99-7 over

99/5

99-5

98-4 99-7

77

P?. coli.

None None

None

None

None

Professor Sims Woodiiead's Reply.

Even if sewage in small quantities, or gradually increasing quantities, found its way into any

water supply, there would be evidence of this

at once, for there would be an increased absorption of chlorine. If the iodide starch test were made

at intervals of half an hour after and before rain,

the assistant would simply go on adding chlorine until the violet reaction was again restored. In this way without any bacteriological examination or any complicated chemical examination, the

bacteriological ̂ purity of the water might be

effectually maintained.

Tarle TV.

The raw water used for this series of tests was

made by contaminating tap-water with the filtrate from fresh horse manure, 2 to 10 c.c. of filtrate

being added to each gallon. The quantity of chlorine used, u<as 0'Jf. part per 1,000,000*

Apr I 21st, 1011.

Percent, of tubes containing"j Raw water ... 100

gas after incubation for > Chlorinated 48 hours. J water ... 0

Number of colonies after j A\a^ei ??? ">000

48 hours incubation. ) (-hl?J"iated \ water ... 50

The bacteria not

destroyed were spore formers, chiefly bacil- lus subtlis. Consider- able organic matter

present hi raw water.

Further Examples and Evidence.

London water for the past six months has been treated after preliminary filtration with one part of chlorine to 5,000,000 parts of water and shows

no B. coli in 10 litres of water.

Xew Jersey (U. S. A.) water is sterilized by one part in 5,710,000 chlorine. The following table from Milton ,T. Rosenau's

Preventive Medicine and Hygiene (D. Appleton and Company, London), shows the results of water sterilization in some of the towns in America.

In most of these towns, the water is sterilized by chlorine in the shape of bleaching powder, the average quantity of chlorine used being one part in 5,000,000

Placr.

Albany Binghampton Elinira Hornell Hudson Ithaca Rensselaer ...

Schenectady Troy Watertown

Deaths per 100,000 from Typhoid.

^ g & <D ?

CD > 00

t?0 ^

H a> a > ? ?

88-8 39-3 54-9 42 "2 64-3 67-2 95*5 25-0 58-2 94-7

*> "?_>> IS a>'?< s ? ft

<5 3 o > 00

MO b I a, ci o I SR ?

s* ft-w ? e aj q o3 l. o "tj

5?*

23-7 73-0 11-7 72-2 41*5 24'4 247 41-4 31'9 50Tj 14*6 78'3 54*4 43-0 14-4 42-6 3D0 46-8 36-9 61*8

* I introduced cylinders of dry liquefied chlorine gas in 1903 and sent one to Army Headquarters, India, in 1905 and again in 1906 and 1910. In 1905, at a sanitary conference in London, I demonstrated the sterilization of water by means of a steel cylinder holding 20 pounds of liquid chlorine.

354 THE INDIAN MEDICAL GAZETTE. [Oct., 1917.

It was largely through the publications of such well-known men as Professors Hewlett and Sims Woodhead that chlorine and hypo- chlorites have acquired such prominence in water sterilization in Europe, and at the beginning of the war they gave it the confidence that was

necessary for its adoption by the army. They have always very kindly referred to my priority of work on the subject.

It is thus an established fact that chlorine does sterilize water. The only points requiring to be settled are?

(1) The dosage. (2) The method.

1. The Dose. The Army Sanitary Committee (Precis No. 43),

has issued the following notice on enamelled iron

plates with a test apparatus :? Sterilization of Water by Chloride of Lime

(.Bleaching powder.) Experiments have shown that if a trace of

free chlorine is maintained in water for half-an-

hour, the microbes causing water-borne diseases

will be killed. The dose is therefore easily settled, add available

chlorine till a sample of water shows a faint blue with potassium iodide and starch. In my experi- ence, actual bacteriological experiments show that while 1 in 7,000,000 chlorine is sufficient to

sterilize water from a good source, i.e., almost free of organic matter, and 1 in 5,000,000 for

ordinary river and lake and canal waters, this

amount of chlorine does not give a colour reaction with starch and potassium iodide. I have

conclusively proved this point by taking daily samples in the case of canal water supplied to camp Moussot in Marseilles, the quantity of chlorine used for sterilizing it was 1 in

5,000,000, and the number of B. coli always above 300 per c.c. in the raw water. The treated

water, though giving the taste of chloramines

referred to above, always failed to give the starch iodide test and was always sterile in 15 c.c.

samples. It is abundantly clear therefore that the law which maintains that if treated water contains sufficient chlorine (nascent oxygen), to

give a blue or mauve with starch 'potassium iodide, that water is sterile, as regards non-

sporing bacteria. This test also forms a check to the efficacy of

any vaunted chlorine or h}'po-chlorite sterilizer. The Method.

A.?For Municipalities in India. With the foregoing evidence, and a vast more

available but not quoted for lack of space, the

cheapest, surest, and simplest procedure for

sterilizing water for municipalities is as follows :? 1. Sedimentation, or partial filtration to

remove mud particles and make the water clear.

2, Sterilization by chlorine.

In Europe and America chlorine sterilization offers no difficulty as chloride of lime * Ca (0C1) CI (Odling), can always be obtained fresh and active. It is made by absorbing clorine in lime.

In India chloride of lime cannot be used as it

very rapidly deteriorates through giving up some of its absorbed chlorine or available oxygen under the influence of temperature (90? to 100?F.) and all of it under the influence of carbon dioxide and moisture which act very rapidly when the air temperature is above 80?F.

Ca(OCl)Cl = CaCl2 + 0. Ca(OCl)Cl + COa = CaC03 + Cl2.

Finally it is impossible to hermetically seal

chloride of lime except in glass capsules. It is obvious that six times as much chloride of

lime has to be used if it contains only 5 per cent, available chlorine in place of 30 per cent. We have therefore either to import chlorine

as the compressed and liquefied gas in steel

cylinders (in place of importing it absorbed in

lime), or to manufacture it locally. The latter in war time is the simpler method for municipa- lities and standing camps. Power is necessary for pumping the water; a very little more is

necessary for preparing chlorine from salt by electrolysis. The principle is simplicity itself. Two oblong shallow tanks each holding 500

gallons of water are erected. Common salt in the quantity of one pound to each 10 gallons is added. This makes 1 per cent, salt solution. Into each tank is introduced 12 carbon rods

(as used for large searchlights), supported by narrow paraffined hard wood boards. In each tank is also a small wooden paddle wheel to set

up a current (fluid) in the water. The electrodes on one side are connected with

the plus wire of a dynamo, and the other set with the minus wire. A fuse must be introduced and a resistance of

glow lamps. The positive electrodes wear away rather rapidly in spite of being carbon, and so must be renewed every few days. The salt is split up into chlorine and sodium,

which recombine to form sodium hypo-chlorite, but some chlorine is always lost, and hence the

fluid becomes strongly alkaline as the electrolysis proceeds.

NaCl = Na + Cl.

Na + H20 = NaOH + H. 2NaOH -t- Cla = NaOClNaCl + H20.

The fluid heats up ; when the temperature rises to 70?C. the current is turned on to the other tank till the first has cooled, when this is again

electrolysed.

* Chloride of lime, bleaching powder, calcium hypo-

chlorite. and chlorinated lime are different names for the same substance.

Oct., L917.J THE VALUE OF CHLOROGEN. 355

The quantity of available chlorine produced is tested by adding a few drops of 10 per cent,

potassium iodide solution to a sample of the

electrolysed salt, and comparing the yellow tint

with a standard 0*4 per cent, solution of iodine.

When the tints are equal, the electrolysed salt

solution contains 00*8 per cent, of chlorine i.e. 1

in 1,250. One gallon of this will sterilize' 4,000 gallons of water giving 1 part of chlorine in

5,000,000 parts of water, i.e., 50 pounds of salt when treated by electricity will sterilize 2,000,000

gallons of water. This is without carrying the

electrolysis to the theoretical degree which would

give more than 0'25 per cent.

When prepared, the electrolysed salt solution is allowed to flow into the main channel connecting

the filter bed with the clear water storage tank. I have prepared and used this solution on the

large scale; it has only one drawback, it will not

keep; but this is of no importance for municipal

purposes. Its great advantage is that it gives absolutely no taste to the water. This method of

preparing chlorine is used on the large scale for

bleaching cotton in Bombay.

B.?For Army Purposes and Individual Use.

Here again the choice of the correct method is

obvious through applying the law that practicabi- lity is essential for efficiency and simplicity for

universal adoption. Chloride of lime is ruled out

because it is unstable, its composition unreliable, and it has not only to be weighed out but its

chlorine content titrated, and finally it oives an

obnoxious taste.

In Mesopotamia last June, chloride of lime was issued to the river steamers and units in

paper packets. It contained no available

chlorine, the steamers were crowded with troops, and the Tigris foully contaminated.

This instability of chloride of lime and its

failure in sterilizing water in the East cannot be too strongly insisted upon as sufficient unspeakable misery and suffering has already been caused by the non-recognition of this point.

2. The less said about the chlorine apparatus the better.

The diagram gives the apparatus. The gas

produced is a mixture of CI and C10?.

The directions are as follows :? 15 grains of KC103 and 2 drachms of HC1 are put

in the bottle " A " and the gas is conducted by

means of a rubber and glass tube through a pint or 30 oz. of water in the bottle " B.'' This forms sufficient chlorine water to sterilize 100 gallons of water. Its takes about half an hour to get off all the gas. The directions include that the bottle " A " should be constantly shaken and warmed.

Chlorine rapidly errodes rubber tubing, and makes rubber corks brittle, and not gas-tight. Ordinary corks are rapidly destroyed" and ̂ yet most apparatuses in Mesopotamia (1916) were supplied with ordinary corks. The apparatus soon leaks, and as the gas has to overcome

6 inches of water pressure a great quantity never reaches the bottle

" B."

In a country where men drank 2 gallons a day such an apparatus could not cope with the daily requirements of 200 men and yet the allowance was one apparatus per regiment.

In 1916, the failure of this apparatus to

sterilize water destroyed many a brave fellow. 3. Titrated solutions of chloride of lime

(calcium hypochlorite) are ruled out, because calcium forms an insoluble carbonate, and thus

constant layers of fresh Ca(0Cl)3 replace the Ca precipitated by the atmospheric C02, and so the fluid deteriorates rather rapidly.

I have given this solution a very thorough trial, and had reluctantly to give it up.

4. The only possible chlorine compound remaining is sodium hypochlorite (IVaCIO).

This is only feebly acted on by C02 in an open bottle as the carbonate of sodium is soluble and

does not deposit to leave exposed further layers of NaClO. When concentrated it is stable for

12 months and longer even in India. In the

presence of NaOH it is indefinitely stable.

XaOH further protects the NaCIO by neutralising any C02 that may reach it.

This is therefore the only logical compound to use for sterilizing water for the private individual or the soldier. Sodium hypochlorite when combined with 1 per cent, sodium hydrate has

been given the name of chlorogen. Ghlorogen is now prepared on the large scale

in India. The process involved is roughly as

follows:?

Freshly imported chloride of lime is well

macerated with water, and a clear concentrated

solution of calcium hypochlorite produced. Ca(OCl)Cl + HaO = Ca(0Cl)2 + CaCl3 + H90. This fluid is then freed of impurities and

particularly chloro-oxy compounds other than

XaClO, and titrated till it contains 6 per cent, available chlorine. It is then treated with sodium carbonate till all Ca is precipitated.

Thus Ca(0Cl)3 + Na4C08 = 2 NaC10 + CaC08. This fluid is again titrated to ensure the

presence of 5 per cent, available CI, and to

35G THE INDIAN MEDICAL GAZETTE. [Oct., 1917.

it is then added NaOH to make a 1 per cent, dilution.

This fluid has remarkable solvent properties, and dissolves cork, wood, leather, etc., but does not dissolve glass, porcelain, or rubber, and hence can be kept in suitable stoppered bottles.

It has a faint sweet smell suggesting chloroform.

The I)ose required for sterilizing Water.

For simplicity one must arrange a dose measur- able by the imperial fluid measure, and a suitable time, the standard always being that the treated water must give a blue with potassium iodide and starch at the end of half-an-hour.

One in 5,250,000 parts of chlorine as chlorogen gives a faint but distinct blue with starch and

iodide in the case of tap water. This quantity corresponds to j? drachm of chlorogen per ] 00

gallons of water. It is a dose that would be

useful for railway, mill, and factory supplies when the water used is always from the same source.

But for general and military purposes, because the organic content of the only available water

may be high, four times this dose should be used with a period of contact of half-an-hour, i.e., 2 drachms per 100 gallons. This quantity, 1 in

1,280,000, is sufficient to sterilize muddy water, e. g., from an irrigation channel running along the Mall in Peshawar. It is sufficient for all river, pond, and lake water met with in India, and

especially the Sliat-el-Arab and Tigris rivers.

Though the action is extremely rapid, the time recommended is 30 minutes for quantities of

50 gallons and upwards. For personal every-day use the most convenient

plan is to keep the chlorogen in a tiny stoppered bottle with a glass rod attached to the stopper as

is used in the case of concentrated scents.

The rod picks up ^ to 1 drop of chlorogen, and this is stirred into a glass of water holding from to 1 pint, and gives an available chlorine content of 1 in 131,200 to 1 in 202,520. The

sterilizing action is instantaneous, i.e., as rapidly as one can take a sample after adding the

chlorogen (3 seconds). For home use a 2-oz. bottle is the best and

a dropper. One drop is added to each gallon of

water, or five drops to a kerosine oil tin. For military purposes.?One-pint and one-

quart bottles are supplied. Taste.?We are all familiar with the taste of

water treated with chloride of lime (and the chlorine .apparatus); this is not due to hypo- chlorites but to undefined compounds of chlorine and oxygen, and the taste cannot be removed as can the taste of pure hypochlorites or chlorine by hypo-sulphite or sulphite of soda. Thus :?

Na2S08 + XaCIO = Na2SO+ + NaCl. or

Xa,S03 + Cl2 + H,0 = Xa?S04 + 2HC1.

A trace of KI is necessary to split up tlie CI?0 compound and the resulting iodine is

then absorbed by the sulphite. It was the dis-

covery of this point that made it possible by introducing a catalytic agent, to prepare pure Ca (0C12) and from it pure NaClO. From the foregoing it is inferred that chlorogen

(even when 1 drop is added to half a pint) gives no taste to water, and this is actually the case. We have thus in chlorogen an eminently

practical method of chlorinating water without

giving a taste. Occasionally with water filtered

by the usual household filters, there is a taste ;

this is due to organic matter added to the water

by the filters, and the removal of atmospheric C02 and ox}rgen.

The compound formed is probably a chlor-

amine, i.e., a CI substitution product of ammonia.

The Method of Action of Chlorine and

Hypochlorite.

Chlorine, hypochlorites, ozone Og, H,02, KMn04, all act in the same way by liberating nascent oxygen; they all give the typical blue with potassium iodide and starch popularly considered to be the test for free chlorine. Indeed, I know

of no way of distinguishing chemically very weak solutions of chlorine, hypochlorites, hydrogen peroxide, and ozone in the presence of chlorides; as all their reactions turn on the properties of

nascent 0. A molecule of CI may be looked upon as an

atom of 0.

Thus Cla + H20 = 2 IICl + 0. In the presence of organic matter or bacteria,

sodium hypochlorite instantly becomes sodium chloride, parting with its oxygen to the organic matter.

Thus NaCl0=NaCl + 0. Also H903 = H90 + 0. Also 03=02 + 0. If blood or serum be added to chlorogen,

oxygen bubbles form in the same way as when

H203 is mixed with blood. NaCIO is very similar to H90a, but fortunately more stable.

Water is thus sterilized by chlorogen through the NaCIO becoming NaGl. On adding Ivl to a dilute solution of chlorogen,

iodine is liberated either by the nascent O or CI. Thus KI + C1 = KC1 + I.

or

2KI+NaCIO +H20=NaCl + T2 + 2K0H.

The Bacteriological Tests.

The Standard Contamination.

This consists of one part of cow dung in

100,000 parts of tap water; this gives at least 5,000 B. coli per c.c. The emulsion of cow

dung must be filtered through wool or filter

paper to remove particles.

Oct., 1017.] TO CLEAR MUDDY WATER. 35?

Or with typhoid or para-typhoicl bacilli by adding two loopfuls of an emulsion, made by adding 2 c.c. of water to an agar culture, to

80 c.c. of unboiled water. This gives about

500,000 organisms per c.c.

The standard culture medium for the B. coli is

lactose neutral red peptone, or shake cultures in

neutral red lactose agar.

For para-typhoid, glucose broth, or shake

cultures in glucose agar. For tylipoid, plates are

necessary.

For routine water testing, the most convenient

medium is lactose neutral red or litmus carbolic

peptone. It is made as follows :

Take peptone 5 grammes, water 20 c.c.

Make faintly acid, and boil till dissolved.

Filter, and make faintly alkaline to litmus, and

add 5 grammes lactose and make up to 25 c.c.

Now add i c.c. of 1 per cent, neutral red or

purified litmus, and i c.c. of carbolic acid (liq.) and place in a bottle with a pipette through the

cork. To 5 c.c. of the water sample add c.c. or

6 drops of the medium, and incubate for 24 hours,

or leave at room temperature for two days. The

presence of coli is shown by the development of

acid and gas. The development of acid alone is

sufficient to condemn the water.

The (juantity of carbolic acid present (in the

water) is 1 in 2,000. (One in 1,000 has no

inhibiting action either on the coli group or

pyo-genic cocci, while the 1 per cent, carbolic

acid in the medium keeps it sterile.) Or agar pills made according to the following

formula may be used :

Powdered agar ? ?? ... '15 gramme.

Peptone ??? ??? 0/o ,,

Lactose ??? ??? 125 ,,

Neutral reel ??? ??? a trace.

Carbolic acid ??? ... '005 gramme.

to make one pill.

Directions.

Place 3 c.c. of water in a test tube, add one

pill, and dissolve by heat till agar jelly is pro- duced. Plug with wool, and boil till steam

escapes through the plug ; this sterilizes the plug. Allow to cool to 40 C., then add 5 c.c. of the

water to be tested, shake and allow to set in an

upright position. Each li. coli is represented

by a gas bubble. It Di'List be clearly i ecogitised that cliemical

sterilizers are unable to 1 eaclt oactena ensconced

in large mud and organic particles, hence

muddy water is occasionally not sterilized unless

first strained through cloth. The finer mud and

other particles which pass through a filter paper

or a wad of wool, or a piece of cloth giving an

opalescent water, do not interfere with steriliza-

tion. But the general principle holds good. Water, before it is good for drinking, should be fairly clear even though treated with chlorine, iodine, etc., as otherwise the water tastes

muddy. Having prepared the standard artificially con-

taminated water, or in the case of canal, river, and well water naturally contaminated (and they all are), 5 c.c. samples are placed in the special medium (lactose for coli) as controls. The

sterilizer, CI., chlorogen, etc., is then added in the quantities stated, and after the proper interval 5 c.c. samples are again planted in the test

media.

In the case of chlorogen i the dose stated, i.e., 1 drachm per 100 gallons will be found to

sterilize the standard contaminated water in

two minutes.

The preparation of drinking water therefore

entails two processes?clarification and steriliza- tion. If the water is clear, as fortunately it

generally is in wells and streams, sterilization

alone is necessary. In large rivers like the

Tigris, Ganges, Jumna, and Brahmaputra, the mud

particles are small and almost purely inorganic, and hence the water can be readily sterilized

in a few seconds, without clarification, but still, except in emergencies, it should be cleared.

To Clear Muddy Water.

The very best and quickest method is to add one grain of alum permanganate to each gallon of the water. The substance is simply sprinkled on to the surface of the water to be cleared

which is then stirred. Alum permanganate consists of 20 parts of burnt alum and 1 part of jjermanganate ol potash. Or 1 grain of

burnt alum per gallon or 3 grains of crystallized alum may be used.

The modus operandi is as follows :? The alum interacts with bicarbonate of lime

present in water to form aluminum hydrate; Al2(So4)b + 3Ca (HC0g)2 + 2A\ (0H)s + 3CaS04

+ 3C02. The permanganate in the presence of organic

matter loses its oxygen and becomes manganese

hydrate and potassium hydrate ; the potassium hydrate further precipitates some chalk from the water.

The net result is that a fleecy cloud forms in the water which attaches itself to the fine mud

particles, and the entire lot then sinks to the bottom in two to four hours, leaving the water clear, and purer of organic matter.

(In connection with the latter it is obvious that the trace of KMnO is an advantage.)

358 THE INDIAN MEDICAL GAZETTE. [Oct., 191?.

In practice, it is not convenient to first clear

the water and then add the sterilizer, as this

means two operations and the stirring required spoils the clearness of the water. The best plan is to add the clearer preparation

first and when it is thoroughly mixed, to add

the sterilizer. The whole operation for 100

gallons takes less than five minutes. And the water will be found clear, sterile, and tasteless in two hours' time.

If the above clearer is not available, lime or-

washing soda may be added, or the mud allowed to settle by storing the water six to twelve hours after adding the sterilizer.

Starch Iodide Testing Fluid.

This is made by adding 5 grains of starch to

1 ounce of water, and boiling till dissolved.

When cool, add 5 grains of potassium iodide, 5 grains of zinc sulphate, and 5 grains of alum. The object of the zinc is to prevent the

formation of dextrine. The alum makes the test

more sensitive.

Contamination of the Water after

Sterilization.

Even with highly polluted waters, in the case

of chlorogen the available chlorine or oxygen remains in an active state for 48 hours, i.e., the

water is antiseptic, and sterilizes any polluted water that may find its way into it. This

is not the case with bleaching powder or

chlorine water.

Toxins and Alkaloids in Water.

In many places, water though boiled does not

prevent epidemic diarrhoea ; this, I am convinced, is due to toxins and alkaloids picked up by the water when percolating through rotting leaves, etc. It is a well known and remarkable fact that if such water be treated with chlorine or

iodine the diarrhoea stops, due no doubt to the chemical destruction of the laxative toxins and alkaloids.

Previous Articles on this Subject.

(1) "A Chemical Method of Sterilizing Water without Affecting its Potability," Public Health, July, 1903.

(2) "The Chemical Sterilization of Water," Indian Medical Gazette, August, 1905.

(3) "The Chemical Sterilization of Water," Journal of Preventive Medicine, October, 1905.

(4) " Further Experiments on the Bactericidal Powers of

Chlorine and Iodine," with a Note on their Application to the Purification of Water on Field Service, Indian Medical Gazette, December, 1905.

(5) " The Chemical Sterilization of Water," Bombay Medical Congress, 1909.

(6) " The Chemical Sterilization of Water for Military

Purposes," Journal of the lloyal Army Medical Corps, May, 1912.

(7) " The Chemical Sterilization of Water for Military

Purposes, Journal of the Royal Army Medical Corps, Febru- ary, 1915.