= 
On definite Proportions. 167 
to constitute with it a neutral compound ; and the acid and the 
oxide must therefore contain equal quantities of oxygen; and 
71-7 parts of the oxide must take up 1973 of carbonie acid : 
the remaining 8°67 must be water, containing 7°5 of oxygen. 
This quantity of the oxide contains 14:34 of oxygen; so that 
the oxygen of the water is half as muchas that of the base. 
The slight difference in the results must depend on a little acci- 
dental moisture left in the oxide, from the imperfection of the 
process of drying. 
Carbonate of copper, precipitated from a cold solution, affords 
a very bulky powder, of a blueish-green colour: but when a boil- 
ing heat is employed, we obtain a heavy, fine-grained, yellowish- 
green precipitate. I at first considered these two precipitates 
as different carbonates, and attempted to collect the former, and 
to wash it with cold water; but it was converted by this process, 
in great measure, into the heavier yellow-green substance, and I 
could not obtain it in a pure state. I had accidentally placed on 
the sand-bath some carbonate of the oxide of copper, precipi- 
tated the day before, and still remaining in the fluid: when the 
carbonic acid had been expelled from the fluid, I observed that 
the carbonate of the oxide of copper, next to the bottom, col- 
lected into masses, and became of a yellow-green, without the 
least appearance of effervescence; and this effect extended by 
degrees upwards as the fluid became warm. The alteration in 
the form appears therefore to depend not on any alteration in the 
quantity of carbonic acid, but merely in that of water ; exactly as 
the carbonate of the protoxide of zinc, in a temperature below 
the boiling point of water, sets at liberty the water combined 
with it, and unites into heavier grains, and as the blue hydrate 
of copper, when the fluid is heated, separates from the water, 
and is deposited in the form of a black oxide. Other subsalts of 
coppér also, which, when they are precipitated cold, are light 
and bulky, become heavier by the effect of heat, and assume a 
yallower colour. 
6. Submuriates. 
. We have found by some of the former analyses, that the mu- 
riatie acid, in the submuriates of the oxide of copper and of the 
protoxide of lead, is combined with four times as much of the 
base as in the neutral salt. Since the muriatic acid must contain 
twice as much oxygen as the base by which it is neutralised, the 
oxygen of the acid in these subsalts amounts only to one half of 
that of the basis. 
7. Conclusions. 
From these experiments | think myself authorised in drawing 
the following inferences respecting subsalts. 
: L4 a.) The 
