230 The Future Water-sujyply of London. [-^V^^h 



general properties of cLokine, as far as tliey liave been ascertained, 

 are well suminccl uj) by Dr. Farr. Its development is arrested by 

 acids; and this, no doubt, accounts for tbe efficacy of sulphuric 

 acid in promonitoiy diarrhoea, and affords a probable explanation of 

 the apparently partial and occasional action of the poison. No 

 doubt, certain favourable conditions of the body are necessary for 

 the development of the germs, and these conditions may chance to 

 be absent in any given number of cases. Dr. Frankland has found, 

 as Chaveau found with vaccine granules, that chohine cannot be 

 separated from water by filtration — a fact which, from the exceeding 

 minuteness of the cholrads, is not to be wondered at. Careful 

 filtration, no doubt, removes very much of the noxious matter, the 

 cholrads being probably entangled by the solid matters separated ; 

 but their comj^lete separation would appear to be impossible. This 

 most alarming fact is, however, to some extent, neutralized by the ■ 

 probability that a certain quantity of the poison is required to 

 render its operation at all a matter of likelihood ; * and by the 

 further certainty that the germs cannot live for any great length 

 of time in the water, unless recent foecal matters are present ; in 

 which case, it is of course possil)le, that they may develop and 

 reproduce themselves in the water, though no distinct evidence 

 on this point has been obtained. Finally, a certain external tem- 

 perature is necessary for the action of the poison ; and when present 

 in small quantity, it is absolutely impossible to detect it by chemical 

 methods. 



The whole history is unpleasant in the extreme ; and the drinkers 

 of sewage-contaminated water will be apt during warm weather to 

 think more of the horrible possibility connected with their sparkling 

 beverage, than even of any of the probabilities which its vendors 

 may be able to allege in its defence. To take the case of the present 

 water-supply of London. There can be no doubt that the sewage 

 of thousands upon thousands of persons is thrown into it before it is 

 collected by the companies. When cholera is prevalent, cholrine must 

 be thrown in with this sewage, which at all times must contain the 

 germs of some zymotic disease. Now it may be, and probably is in 

 many cases, that the whole of the soluble organic matter is oxidized 

 before it is consumed as drink ; but who would like to trust 'to this 

 probabihty ? And even if the whole of the unorganized matter of 

 the water were oxidized, there exists no security that the organized 

 germs, the really mischievous part, would also be oxidized and ren- 

 dered inert. Dr. Frankland points out,t that such germs would 

 probably resist oxidation for a longer time than mere organic matter 

 in solution. To quote his forcible illustration, an egg thrown whole 



* Farr, op. cit., xv. 



t Frankland and Armstrong * On the Analysis of Potable Waters,' Journal of 

 tlie Chemical Society, March, 18G8. 



