MUTlIAt DECOMPOSITION. 
27 2 
Discoveries 
and doctrine 
of Berthollet 
The insoluble 
salts have 
not been duly 
attended to.^ 
Fpurcroy’s 
conclusions in 
bis general 
work are con- 
jectural. 
Instances. 
.explanations, frequently very ingenious, but they did nut ope- 
rate to render the truth of a principle suspected, which had 
been considered as irrevocably established. M. Berthollet, by 
submitting to new experiments those facts on which the cele- 
brated chemist of Upsal had founded his doctrine, soon disco- 
vered that they would admit of another interpretation, and 
his learned researches have led him to an explanation of the 
phenomenon of the mutual decomposition of the neutral salts, 
•which is no less simple than the first, but has this immense ad- 
vantage beyond it, of predicting, without exception, all the 
phenomena from a mere knowledge of one of the most into-*' 
res ing properties of these bodies. 
Chemistry, therefore, leaves nothing further to be desired 
with regard to the decomposition of the salts to which the 
principle of M. Berthollet is applicable ; namely, relative to 
the sojuble salts. But the insoluble salts are also susceptible 
of exchanging their principles with a great number of the 
soluble salts. This class of phenomena, though almost as nu- 
merous as that which exclusively embraces the soluble salts, 
and capable of affording new resources to analysis, has not yet 
been examined in a general manner. 
There is certainly to be found in the system of chemistry of 
M. Fourcroy, a very extensive table of the. mutual decompo- 
sitions of salts, which comprehends a considerable number of 
cases of the kind in question. But I am induced to believe, 
that such decompositions as do not relate to the soluble salts, 
have not been ascertained by observation, but only anticipated 
according to the theory adopted by this illustrious chemist. It 
may be maintained, in support of this assertion, that no memoir 
has been published upon this subject, and that a great number 
pi facts are contained iif these tables, which are not confirmed 
by observation, arid others which are evidently impossible- 
for example*, we there find that the fluate of barytes is decom- 
posed by the muriate of soda or pptash, and that the result is. 
fhe muriate of oarytes, and the fluate of soda of potash, The 
*, Tom. IV, p. 217. 
author 
