338 Scientific Proceedings, Royal Dublin Society. 
The results of this inquiry further showed that careful deter- 
minations of the more obvious products of each stage of fer- 
mentation, viz. carbon dioxide and of ammonia during the one, 
and of carbon dioxide (if formed), and nitrous and nitric acids 
during the other stage, together with accurate determinations of 
the dissolved atmospheric oxygen consumed during both stages, 
afford data by which both the character and actual quan- 
tity of fermentable matters, present in a polluted water, could 
be estimated with sufficient accuracy for the purpose of water 
analysis. 
In this short paper I propose to give an example of the applica- 
tion of this method of inquiry to the examination of the water of a 
small stream for unfermented, or, in other words, polluting, © 
organic matters. 
At the time when the samples, with which I experimented, 
were collected, the volume of water flowing through the stream 
was very small, probably not equivalent to as much as 100,000 
gallons per day. The stream consisted almost, if not entirely, 
of drainage waters from cultivated land, and received, some 
little distance above the points at which my samples were taken, 
considerable volumes of drainage matters from neighbouring 
houses, a portion of which, however, had been subjected to a 
process of purification before being allowed to flow into the 
stream. . 
Two samples were collected on the 28th April, 1894, at 1 p.m. 
One sample was taken from a point about 200 or 300 yards below 
the lowest discharge of house drainage, above referred to; the 
second sample was gathered from the lower end, and near the 
outlet, of a small pond-like enlargement of the stream at a point 
about 100 or 200 yards below the first. In this second case the 
sample collected was taken at a depth of about one foot below the 
surface of the water. 
The bottles in which the two samples were collected were com- 
pletely filled and carefully stoppered, and conveyed without delay 
to my laboratory. Both examples were examined by the ordinary 
method of analysis as well as by the method of examination above 
referred to, on the afternoon of the same day as that on which they 
were collected. 
