Avrenry—Studies in Chemical Analysis of Fresh & Salt Waters. 349 
greater ease and more quickly than would be anticipated by 
chemists not practically acquainted with it. With the special 
apparatus described in my original paper (see also Chemical News, 
vol. 62, pp. 196-199, and 204-206) for extracting, measuring, 
and analysing the gases dissolved in the water, and employing an 
extraction flask of not less than 1600 c.cs. capacity, and working 
with 100 c.cs. of a sample of water, I find that the dissolved gases 
may be extracted, measured, and analysed in six samples, one after 
another, easily within six hours, including the washing out of 
the Eudiometer and Laboratory vessel necessary between each 
analysis. 
I am also induced to again draw attention to the aération 
method, in that I am now prepared to describe a modification of 
it, whereby the ‘‘ oxygen absorbed ” by fermentation in a polluted 
water may be determined by a single gas measurement. A 
detailed description of this modification will shortly follow in 
Part II. of this paper. 
APPLICATION OF THE AERATION Meruop to THE Srupy oF A 
Siticgutity Pottutrep Non-tTipaL River WatTER. 
The value of the aération method is well illustrated by tlie 
results of analyses, recorded in Table I., on next page, of samples of 
a slightly polluted non-tidal river water, viz., the river Liffey, 
from immediately above Chapelizod to the weir at Island Bridge. 
The purpose of the examination of this water was to ascertain 
whether it was a safe water for out-door and strictly non- 
dietetic use. 
The water is pumped up from a point just above the weir, and 
is stored in a large tank for the purpose of distribution. 
Samples 1 and 2, Table I., were collected on the same day, 
September 21st, 1899, during dry weather. The first from imme- 
diately above the weir, and the second from the bottom of the 
distributing tank into which the water was being pumped at the 
time. 
The ordinary analytical determinations recorded in Table I 
cannot be regarded as indicating the existence of any fresh 
polluting mattersin the water; the only conclusion that can in fact 
be drawn from them, is that the water is an excellent river water. 
