ADENEY—Organic Matters in River Waters. 341 
which characterize a first stage fermentation, viz. a breaking down 
of unfermented organic matter, and a conversion of its carbon and 
nitrogen into carbon dioxide and ammonia. 
The results given for the second sample show that, notwith- 
standing the fact that it yielded a decidedly larger quantity of 
albuminoid ammonia than the first, it contained much less unfer- 
mented organic matter, and that in consequence, we have less 
carbon dioxide formed; and instead of ammonia being formed, 
more than half of that originally present was oxidized to nitric 
acid. 
Judging from the quantity of dissolved oxygen consumed, and 
the quantities of carbon dioxide and nitric acid formed, we may 
safely regard the former product as aresult of a first-stage fermen- 
tation; the latter product resulted, of course, from a second-stage 
fermentation or true nitrification. 
Ii these experiments had been carried farther, as they could 
have been in the manner described in my first Paper, it would 
have been possible to have determined the exact volume of oxygen 
necessary for the complete oxidation of both the unfermented 
organic matters and ammonia present in each sample. 
They go sufficiently far, however, to render it possible to draw 
definite conclusions as to the extent of pollution of the stream 
water by organic matters at the two points examined. In the 
first place, both samples were highly oxygenated at the time they 
were collected, sample No. 2, more especially, notwithstanding the 
fact that it was collected afoot below the surface of the stream. 
It may therefore be concluded that, since both samples were neutral 
to test-paper, and were therefore in a condition favourable to bac- 
terial fermentation, the organic matters were present in too small 
quantities to encourage a bacterial growth sufficient to cause a rapid 
consumption of the atmospheric oxygen dissolved in the water, 
and thereby to endanger fish or the higher forms of vegetable 
life. 
In support of this conclusion, that fermentation was proceeding 
very slowly in the stream at the points examined, I may quote 
an experiment which I made with a sample of the stream water 
gathered a few days previous to that on which the two samples 
under discussion were collected. 
