1877.] 



Organic Matter in Potable Water. 



153 



senses. And yet the question of the wholesomeness of water hinges 

 mainly upon the presence or absence of such putrescent matters, as they 

 themselves are the cause of derangements of the human system. Most 

 serious, however, are the consequences when those low forms of organic 

 life, which in all probability form the specific poison of cholera, typhoid 

 fever, and other diseases, gain admission to drinking-water polluted by 

 putrescent matter. 



A number of observations point to the conclusion that these organisms, 

 or their germs, are not infectious as long as surrounded by fresh organic 

 matter ; but as soon as fermentation sets in, they show their poisonous 

 virulence. Thus it has been observed that the discharges of cholera and 

 typhoid patients are not infectious as long as they are fresh, but by 

 putrescence their poisonous character is developed. 



Chemical analysis is incapable of discriminating between living or 

 dead, fresh or putrescent organic matters. The microscope reveals their 

 nature more fully ; but it is nevertheless frequently a matter of great 

 difficulty to decide as to the existence or non-existence of Bacteria of 

 putrefaction, or their germs, in water. It thus appeared to me that this 

 information might, in some cases at least, be gained with greater cer- 

 tainty by an indirect method. 



If we want to determine whether a gas be carbonic anhydride, we pass 

 it through potash bulbs, and see whether these increase in weight. Simi- 

 larly the presence or absence of putrefactive agencies in water may be 

 determined by their action upon organic matter. The test I selected is 

 fresh meat, as the slightest putrescent changes in it can most readily be 

 detected by its smell. 



The experiments, which were originally made with a view of deter- 

 mining the improvement of water by certain filtering media, were, with 

 the exception of experiment VIII., carried out in the following manner : — 



On to the perforated bottom (a) of a stoneware vessel (s s) I place 



some fresh meat. The vessel is then filled to about two thirds with the 



