248 M, Barucl on the Process 



dissolves the palladium and silver, but leaves the gold in the 

 form of a brown powder, which may fused into a button in a 

 crucible. Into the nitric 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 chlo- 

 ride contains only palladium. We add to it a few drops of so- 

 lution of sal-ammoniac, then saturate the redundant'acid by am- 

 monia ; the whole palladium is thus precipitated in the state 

 of an ammonia proto-submuriate 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 

 as the above, but with this difference, that the acids ought to be 

 as concentrated as possible. I employ for this purpose nitric 

 acid, at 40° (1.387 sp. gr.) and muriatic acid, at 23^° (1.195). 

 The retort is placed on a sand-bath, with a tubulated receiver 

 adapted to its neck, and it is heated moderately. A brisk 

 effervescence soon arises, owing to the disengagement of much 

 nitrous vapour, and a little chlorine. The action of the heat 

 must be so modified as to produce the most beneficial effect on 

 the solution, without volatilizing the acid. Finally, when the 

 effervescence ceases, the fire is to be augmented till the liquid 

 boils, and till no more orange nitrous fumes are disengaged. 



When the action of the acid is quite exhausted, we decant 

 the liquid into a matrass, and pour on the portion of the ore 

 not attacked the same nitro-muriatic acid, equal in quantity to 

 the first. 



The mixture is to be heated anew, observing the same pre- 

 cautions as for the preceding solution. Finally, we treat the 

 ore five times in succession with the compound acid. By this 

 process six parts of this acid are sufficient to dissolve the whole 

 platinum, palladium, and rhodium contained in the ore. 



8. After the last digestion, which yields only a slightly 



