2>o7 
Copper . 21 
a brick-red precipitate with nitrat of silver, the arsenic acid 
being first neutralized with soda. 
Mr. Chenevix analyses the arseniats of copper in the 
same general way, but with some variations. 
The ore (previously heated moderately to expel and es- 
timate the mere water) is dissolved in dilute nitric acid 
and nitrat of lead poured in. The solution (containing an 
excess of acid and therefore holding some of the arseniated 
lead dissolved) is then evaporated nearly to dryness, and 
alcohol added to complete the separation of the arseniat 
of lead. After which the copper is decomposed by pot 
ash, and is obtained in the state of the brown oxyd. 
Muriat of Copper . 
The composition of this singular ore, found hitherto only 
in Peru, was ascertained nearly at the same time by 
Proust, and by Rochfoucault, Beaume, Fourcroy and 
Berthollet, a committee nominated for the purpose by the 
French Academy. The experiments are instructive. 
The ore thrown on hot coals burns with a beautiful 
blue and green flame, whereas malachite, which it most 
resembles in appearance, gives only a faint green flame. 
Distilled per se, malachite gives no other volatile product 
than carbonic acid and water ; whereas the muriat gives 
in the same process a quantity of oxygen gas with only a 
very small proportion of carbonic acid, and a green liquor 
strongly smelling of muriatic acid and proved to contain 
copper by giving a fine blue with ammoniac The residue 
in the retort was a brown oxyd of copper. This when ex- 
posed to air turns green, shewing therefore that it is not a 
simple, but a muriated oxyd. Part of the muriat of cop^ 
per therefore is volatilized, as it is well known that this 
salt readily rises in distillation. The muriatic acid how- 
ever is not sufficient in this ore to saturate the oxyd of 
copper, and hence by simple boiling in water only a small 
portion is dissolved,*, which gives Juna cornea with nitrat 
tf silver* 
