THE 
SewCOHNOLOGIS 
——_0——_- 
FEBRUARY, 1867. 
——_0--— 
ZEEE NET Y «AND 2H BoA, 
BY H. ST. CLAIRE DEVILLE. 
Translated from the First Chapter of a Sertes of Lectures on 
“ Dissociation,’ published in the “ Lecons de Chimte.” 
(Concluded from our last.) 
N the experiments I have terminated, I have only found 
one single exception; and that is in the case of the 
formation of sulphate of soda by means of two dilute 
solutions, one of sulphuric acid, and the other of caustic 
soda. Sulphate of soda expands at the moment of its 
formation, and ¢ is greater than 0, so that 7 becomes nega- 
tive, which is a nice point to explain. But the study of 
the phenoniena of saturation in these solutions will, I hope, 
enable me to explain this abnormal phenomenon, like the 
contraction of water by heat, or the expansion of bismuth 
at the moment of its solidification, &c.* 
The contraction observed on mixing with water mono- 
hydrated acetic acid or saline solutions is considerable, 
and the cooling of the combination or solution very note- 
worthy, as had already been observed by Rudberg, if I am 
not mistaken. In that case, ¢ becomes negative; and 7 is 
greater than unity. Thus at the moment of the reaction, 
* Since writing these lines, M. J. Regnauld has made observa- 
tions on the subject which lead to a system of explanation far 
superior to my own.—‘“‘ Journal de Pharmacie,” 4 sér., vol. 1, 
p- 401. 7 
NEW SERIES.—VOL. I. DD 
