172 Process fur procuring pure Péalinum, Palladium, &c. 
composed of one part of nitric acid at 25° Baumé (1-210 sp. gr.) 
and three parts of muriatic acid, at 18° (1:14), and heat the mix- 
ture for half an hour. Such acid dissolves all the gold, all the lead, 
the greater part of the copper,’ and a very small quantity of pla- 
tinum, palladium, and iron, while the silver is converted into a 
chloride, which remains mingled with the ore not attacked. After 
decanting the acid liquor, the ore is thrown on a filter, and 
washed with a sufficient quantity of water. The filter-funnel 
being transferred to another vessel, the filter is to be washed with 
a very weak water of ammonia. By this means we dissolve all the 
chloride of silver, which is recovered by saturating the filtered 
liquor with muriatic acid. ; 
4. The solution which contains the gold, lead, copper, and 
iron, with a small quantity of palladium and platinum, being 
added to the water which has served for the washings, the whole 
_ is now evaporated to the consistence of syrup, which is diluted 
with thrice its volume of water, and treated with sulphuric acid, 
drop by drop, to precipitate the lead in the state of sulphate, to 
be afterwards separated by the filter. 
5. Into the filtered liquor a solution of proto-sulphate of iron 
must be poured, which throws down the gold and palladium in 
the metallic state. We decant the liquor, wash and dry the pre- 
cipitated metals. The platinum remains in the liquor with the 
iron and copper. We concentrate this liquor by evaporation, 
then pour into it a sufficient quantity of a saturated solution of 
muriate of ammonia, which throws down the platinum in the 
state of ammonio-muriate. This must be washed on a filter and 
dried. 
6. The gold may be very easily separated from the palladium 
by melting these metals with four times their weight of silver, and 
acting on the alloy with concentrated nitric acid, which dissolves 
the palladium and silver, but leaves the gold in the form of a 
brown powder, which may. be fused into a button in a crucible. 
Into the nitri¢ solution of silver and palladium we pour muriatic 
acid, which throws down all the silver in the state of chloride. 
The liquid freed by the filter from the chloride contains only 
palladium. We add to it a few drops of solution of sal-ammoniac, 
then saturate the redundant acid by ammonia; the whole palla- 
dium is thus precipitated in the state of an ammonia proto-sub- 
muriate of palladium, which exhibits small needles, of a delicate 
rose colour, This salt is to be washed on the filter, and dried. 
7. The ore of platinum which has been successively treated 
with weak nitro-muriatic acid, and then with ammoniacal water, 
to carry off the chloride of silver, is to be strongly desiccated. 
Having replaced. it in the retort, we pour over it a weight equal 
to its own of ‘nitro-muriatic acid, made in the same proportion 
the 
