334 Scientific Proceedings, Royal Dublin Society. 
In order to decide these questions, and especially the effects of 
varying dilution and temperature on the speed, and possibly, on 
the nature of the chemical changes occurring, a very large amount 
of experimental work would be necessary, and for this reason the 
results which we now bring forward must be considered as chiefly 
of a preliminary nature. 
In order to trace the nature of the chemical changes which 
occur when mixtures of sewage and sea-water are left to themselves, 
and the speed with which they take place, we have experimented 
under both fully aerobic and partially aerobic conditions. Indeed, 
in the second series of experiments, the conditions were, in one 
sense anaerobic, as no air, as such, was admitted to the mixture, 
which, however, contained the gases its constituents had dissolved 
from the atmosphere. 
The method of investigation adopted in the second series of 
experiments was that originally employed by Dr. Adeney in his 
very important researches on “ ‘The Course and Nature of Fermen- 
tative Changes in Natural and Polluted Waters and in Artificial 
Solutions.” Briefly stated, this method consists in analyzing, 
from time to time, the gases boiled out im vacuo from the polluted 
water or artificial solution, and thus ascertaining the amount of 
dissolved oxygen which disappears, and that of the carbonic 
anhydride which is produced. 
In our experiments with mixtures of sewage and sea-water, we 
have adopted Adeney’s method; and for boiling out and analyzing 
the dissolved gases, we have used an apparatus similar to his own, 
and, thanks to his kindness, largely constructed under his own 
supervision. Simultaneously with the gas analyses, determinations 
were made in the same sample of the mixture of— 
(1) The “ free’ and “ albuminoid ’”’ ammonia. 
(2) The “oxygen absorbed ” from acid permanganate 
during four hours at 80° F. 
(3) The nitrites by the phenylene diamine process. 
(4) The nitrates by the zinc-copper couple method. 
In commencing a series of experiments, a stock of the mixture 
of sewage and sea-water was made, and a series of bottles filled 
to the brim with it and tightly stoppered. 
