512 
Book II. 
Division II 
Verdegris. 
SALTS OF 
0.56 parts of it are dissolved, and there remain 0.44 
parts in the state of a fine green powder, which remains 
long suspended in the solution. Mr Proust has ascer 
tained that this powder is a sub-acetite of copper. It 
is decomposed by sulphuric acid, by potass, and by dis 
tillation. According to the analysis of Proust, it is 
composed of .... 37 acid and water 
63 oxide 
1o 
Thus it appears, from the experiments of this philoso 
pher, that the verdigris of commerce is composed of 
two different acetites of copper ; the one soluble in wa 
ter, the other insoluble. It is much used as a paint ; 
and crystallized acetite of copper is a frequent ingre 
dient in dyeing compounds. Verdigris is formed in 
great quantities at Montpelier. A particular account 
of the processes followed in that place has been lately 
published by Mr Chaptalt. 
Sp. 13. Oxalat of Copper. 
OXALIC ACID is capable of attacking copper, and it 
combines with great facility with its oxide. The oxa 
lat formed is in the state of a bluish-green powder, 
scarcely soluble in water unless with excess of acid. 
According to Bergman, to whom we are indebted for 
all that is yet known of this salt, 21 parts of copper 
require 29 parts of acid to dissolve them. Oxalic acid 
precipitates this salt from liquid sulphat, nitrat, muri 
at, and acetite of copper . 
* Ann. de Cbim. XXV. 305. 
Bergman, i. 267.