MUTUAL DECOMPOSITION. 
271 
fluids having a strong affinity for it, (of sulphuric acid for 
example through liquid ammonia) which is inexplicable on any 
antecedent theory, is sufficiently explained by this. The 
ingenious speculation of Dr. Bostock limited the carrying 
power of electricity to its action on hydrogen, a defect not 
imputable to him, but to the state of the science at the time 
when he wrote. Since that period, the discoveries of Mr. 
Davy have been unfolded by a train of experiment and induction 
which is probably not surpassed by any thing in the history of 
the physical sciences, and which will form a durable monument 
of the genius and industry of their author. 
VII. 
Inquiries concerning the mutual Decomposition of soluble and 
insoluble Salts. By M. Dulong*. 
T HE phenomena of the mutual decomposition of neutral Bergmauu’s 
salts, so important in their application to analysis, and b?e°elective 0U 
for their connexion with the general theory of chemical affi- attractions, 
nities, have been the object of research by a great number of 
celebrated chemists, since the time when Bergmann inferred, 
that the double decompositions which had been observed before 
his time, are dependent upon the same principle as those which 
take place' when an insulated base or acid are combined ; a fact 
been long before known. The theory which he presents, in 
his dissertation on the affinities, appears so natural, that not 
the slightest doubt arises of his accuracy. Consequently all 
the works which have appeared for the following twenty years 
on this subject, appear to have been undertaken with a view 
to extend this theory, rather than to confirm it by new experi- 
ments. A great number of anomalies, which were observed 
by different chemists, were met by more or less complicated 
* Presented to the National Institute of France, and inserted in 
the Ann. de Ch. LXXXII, 273. 
expla- 
