126 PROCEEDINGS OF THE COTTESWOLD CLUB 



(lo) Exact estimations of the lime and magnesia and of 

 carbonic and sulphuric acids, &c. are made when 

 specially required, and the water is tested for iron 

 and lead, the latter being dissolved from lead pipes 

 by certain peculiar waters. 



The Bacteriology of Water 



I'he organic material contained in water may be living 

 or unliving, chemical analysis does not distinguish between 

 the two, but in the process for estimation of albuminoid 

 ammonia the living and the unliving organic material yield 

 the same result. The living organic material of water, 

 however, carries a portent of greater significance than that 

 which is not alive, owing to the possibility of the living 

 organisms including those that are capable of setting up 

 disease in the human body. It is true that a large amount 

 of organic material in water, particularly that of a nitro- 

 geneous nature, is always indicative of the elements of 

 bacteria, and when such material exists in large amount, 

 the greater is the likelihood of the bacteria of disease being 

 present. Sometimes bacteria increase through the in- 

 fluence of temperature or through some circumstances as 

 yet not well understood, but which apparently has no 

 relation to the amount of food material present. It is 

 possil)le, however, to arrive at an approximate idea of the 

 actual number of living micro-organisms present in a 

 water, and also to some extent to separate them into their 

 individual species. The vast number of bacteria in all 

 ordinary waters and their minute size precludes the possi- 

 bility of actually counting them in a drop of water placed 

 under the microscope, but when a drop of such water is 

 mixed with a gelatinous preparation which is found to be 

 highly nutrient to bacteria, and which has been itself 

 entirely freed from bacteria by exposure to heat, each 

 individual bacterium begins to multiply and in doing so 



