the Oxidation of the Metals, Se, 208 
Proust has observed that mercury kept for some time in a 
solution of corrosive sublimate is changed into: mild mu- 
riate, and Messrs, Fourcroy and Thenard have found by 
the analysis of these two nrercurial salts that the former 
‘contains more acid than the latter. Inthe same way, when 
we expose to the air the white muriate of copper, it is 
changed into green muriate and*into oxide retaining a wi 
acid; an evident proof that the copper takes more acid i 
proportion as itis more oxidated. But it is not enough is 
know that the bighly oxidated metals take more acid than 
those which are less so: it is necessary to show that they 
take the acid precisely in the ratio of their oxidation. 
By repeating several times the distillation of-merenry 
with its oxidized muriate, the whole salt is changed into 
mild muriate, and neither acid nor oxygen gas 1s extricated. 
Tt is therefore evident that there are in the oxidated muriate, 
and in the mild muriate, quantities of acid proportional to 
the quantities of oxygen in the mercury. The analysis of 
these two salts also leads to the same conclusion. Messrs. 
Fourcroy and Thenard found that the oxidated muriaiv 
contains 73 parts of mercury and 20 of acid, and the mild 
muriate 11°6 of acid and 83 of mercury. ‘They. moreover 
found that the red oxide contains twice as much oxygen 
as the black oxide; so that by making the calculation, in 
order to bring the metal to the same weight in both ana- 
Jyses, we see “that the acid in the sublimate and the nuld 
muriate is in the same ratio with the oxygen in the oxides 
of each salt. By comparing under the same point of view 
the analyses of the muriates of copper given by M. Proust 
and Mr. Chenevix, we also obtain the same results. 
I am of opinion, therefore, that we may fairly conclude 
from these facts, that the acid in the salts is exactly pro- 
portional to the oxygen of the oxides *. 
We sce already as a consequence of this principle, that 
by decomposing a neutral metallic salt by a metal suscep- 
tible of also forming a neutral salt, neither oxygen nor acid 
_ ought to be extricated, considering that both are in a ratio 
proper for forming a neutral salt with the decomposing metal. 
~ But the most important result which we can draw from 
the principle that the acid in the salts is proportional to 
*It is very remarkable that, the acid being proportional to the oxygen of 
the oxide, the latter does not follow the ratio of the oxygen when the acid 
passes from the first to the second degree of acidification. A sulphite, that 
of lead for instance, would take more acid if the metal were more oxidated ; 
but it would not take more oxide if the acid passed to the state of sul- 
phuric acid. 1am ignorant how this difference arises. 
the 
