the Axs-eniates of Copper, and of Iron. 203. 
In this ore, I believe, for the following reasons, that the metals 
are in the state I have marked. First, the proportions in the 
ore announce it ; for I always had an excess of weight in the 
total result, if I did not deduct such a proportion of oxygen as 
might be contained in 30 parts of copper. 
Secondly, there is a considerable disengagement of nitrous 
gas. 
Thirdly, the ore does not attract the loadstone. 
And, fourthly, the greater part of the iron, (but none of the 
copper,) is dissolved in muriatic acid, forming a green muriate of 
iron, without disengagement of hydrogen gas. 
No. VIII. Grey vitreous copper ore. (See page 173.) There 
are many intermediate states between this ore and the yellow 
hematitic copper ore ; but they are not fair objects of chymical 
analysis, being merely mixtures of both kinds, in different pro- 
portions. The mineralogist, indeed, may dwell upon them, as 
interesting in studying the products of nature, but they are 
unsatisfactory subjects for the chymist. 
Grey vitreous copper ore, when obtained in its greatest pu- 
rity, is by many degrees the richest cupreous pyrites known 
in nature ; and, in the large way, the metal may be extracted 
by the easiest processes. 100 parts of this ore, in dilute nitric 
acid, left 1 2, which were sulphur. Ammonia, poured in excess 
into the nitric solution, redissolved, with the exception of 4, the 
whole of the precipitate which it had formed ; the 4 were iron ; 
and, from the ammoniacal liquor, 105 of black oxide of copper, 
equal to 84 of metallic copper, were obtained by evaporation, 
and then boiling with potash. 
D d 2 
