THE VALUE OF THE NITRATE FIGURE, ETC. 409 



figure only, such as (a) when we have a group of wells in a 

 circumscribed area with one substance, say, N as nitrates, 

 large in quantity and vastly different in amount in each 

 well ; and (b) where in the same well water some figure, 

 such as chlorine or N as nitrates, varies at different analyses 

 out of proportion to variation in some figures such as the 

 total solids. 



Most authorities appear to almost ignore the quantity of 

 nitrogen as nitrates in a water in forming an opinion as to 

 its fitness for drinking purposes. 



Nitrates and nitrites in water represent, almost exclu- 

 sively, the oxydized nitrogen derived from the decompo- 

 sition of nitrogenous organic matter. When organic matter 

 undergoes decomposition, much of the N passes off in the 

 free state, the remainder combining with hydrogen to form 

 ammonia. As the polluted water containing this ammonia 

 continues on its course in the earth, the N, mainly through 

 the action of so called "nitrifying organisms " in the soil, 

 becomes partially oxidized to nitrous acid, which combining 

 with bases (commonly lime, and less often soda and potash), 

 forms nitrites. Owing to the further action of the same 

 agencies, the nitrites then combine with more oxygen to 

 form nitrates. 



It has been held that by the time the organic contamin- 

 ation in the water has been oxydized to nitrates the water 

 would be rendered sufficiently pure for drinking purposes. 

 But, allowing for the sake of argument that this is so, the 

 water would still have to be regarded as dangerous for 

 drinking purposes, for at any time the agencies responsible 

 for the purification may. be overtaxed, and dangerous 

 pollution pass unchanged into the water. In this connec- 

 tion the following paragraph from "Hygiene and Public 

 Health," Parkes and Kenwood, 2nd Ed., might be quoted: 

 "Although it is now generally believed that the bacillus 



