174 Mr . J. Davy’s Account of some Experiments on the 
a combination of brown oxide of copper. with the acid em- 
ployed. 
Heated slowly in a bent luted glass tube, connected with 
mercury, the native muriat affords water and oxygene gas, 
and the residue is an agglutinated brownish mass, which dis- 
solves in muriatic acid and gives a greenish precipitate with 
potash, and is apparently a mixture of brown oxide of copper 
and cuprane. When the heat is raised rapidly to redness, the 
water expelled is impregnated with muriatic acid, and muriat 
of copper. I have obtained from 25 grains of the mineral 
heated to redness till gas ceased to be produced, just two cubic 
inches of oxygene. This expulsion of oxygene seems to be 
owing to the action of chlorine on the brown oxide to form 
cuprane ; and there is, I have ascertained, a similar production 
of oxygene when heat is applied to a mixture of the deliques- 
cent muriat and brown oxide of copper. 
From these results, which perfectly agree with those ob- 
tained by eminent chemists on the Continent, who have exa- 
mined different specimens of this mineral, it appears to be a 
submuriat of copper, differing in a chemical point of view from 
the deliquescent salt, merely in containing a smaller propor- 
tion of acid. 
The following experiments were made with the design of 
ascertaining the proportions of its constituent parts. 
50 grains of the crystals in powder, boiled in a solution of 
50 grains of potash, afforded 36.5 grains of brown oxide of 
copper heated to dull redness. 
And 20 grains dissolved in nitric acid, and precipitated by 
means of nitrat of silver afforded 12.9 grains of dry horn 
silver. 
