220 
Mr. Chenevix’s Analysis of 
neutralization, evaporation, and affusion of nitrate of lead, (all 
of which operations were detailed in the first part of this 
Paper,) gave a precipitate, corresponding to 35,5 of arsenic 
acid. The first residuum weighed 53. Dissolved, as far as 
they could be, in muriatic acid, there remained 3, which, upon 
examination, were found to be really silica. Ammonia, poured 
in excess into the muriatic solution, redissolved 22,5, which 
were copper; and 27,5 of iron remained behind. The pro- 
portions were, 
Silica 
3 
Arsenic acid - 
- 
- 33>5 
Oxide of iron - 
- 
- 27,5 
Oxide of copper 
- 
- 22,5 
Water - 
- 
12 
98,5 
None of these experiments were sufficient to determine, whe- 
ther this ore is in the state of a triple salt, or merely a. mixture 
of two arseniates. As, in a ternary combination, the proportion 
of acid might vary, it cannot be justly called in to aid us in our 
enquiry. The solubility of one part of the ore being much 
greater than that of the other, and in different quantities of each 
salt, incline more to the opinion, that it is but a mixture. 
Simple Arseniate of Iron. 
This arseniate, exposed to any degree of heat, gave but an 
unsatisfactory result, with regard to the quantity of water. The 
arsenic acid is volatilized from this ore, with peculiar facility, for 
which I shall attempt hereafter to account. 
