34S 
CHEMICAL raiNClPLES. 
Fonnrr state 
merits of ox- 
ides of Gold. 
A uric oxide. 
of that contained in the oxide combined with them. We shall 
begin with the oxides of gold. 
Several chemists have endeavoured to determine the compo* 
sition of the oxides of gold, but with very ditferent results. 
M. Proust, for example, found in one experiment, 8-57 per 
cent, and in another, 31 per cent, of oxigen in this oxide. 
Richter found that it should contain 20-^- per cent. And 
lately, M.Obeikampf found that the oxide of gold contains 
10 per cent, of oxigen. It is known that it is very difficult to 
produce this oxide in a state of purity, and that part is reduced 
during the time of washing as well as while drying. In order 
to obtain a more decisive result than those of my predecessors, 
I thought it proper to follow a different method. 
1. O.xidum auricum- I call by this name the ordinary oxide 
of gold, because I found that gold has also a salifiable oxide, 
contains less oxigen, and which I therefore call oxiduiu auro- 
sum. 
I dissolved pure gold in the nitro-rauriatic acid, and afterwards 
evaporated the solution to dryness, and until the dried mass 
began to give out oxymuriatic gas. The neutral muriate thus 
produced was dissolved in water, and I afterwards digested it 
with mercury, of which the weight was exactly determined, 
and did not exceed , the half of that of the dissolved gold. I 
continued the digestion during four days, triturating from time 
to time the gold which had precipitated. When the gold ap- 
peared to contain no more mercury, I decanted the fluid, and 
washed the gold repeatedly, until the water, by boiling a few 
minutes, on the metallic powder, did not acquire a yellow 
colour. I then dried the gold at the temperature of fused lead, 
and aftejwards put it into a small gkiss retort, in which 1 exposed 
it to a red heat, to ascertain with certainty whether the gold 
contained mercury or not;. I then found that a small quantity 
of mercury had risen in the neck of the retort, TJiis I weighed, 
and subtracted its weight from that of the mercury employed to 
precipitate the gold. The experiment w'as made twice. In the 
first, 9,335 grammes of gold were precipitated by 14,29 
grammes 
