Memoir on Platirm* 11-9 



-the most scrupulous researches were not able to discover the 

 least trace of that metal. 



The residuum when calcined in a platina crucible exhaled 

 at first vapours of muriatic acid, and then a substance which 

 gave a blue colour to the name of charcoal : at last there 

 remained a black powder, which was not attacked by acids. 

 They then subjected this black powder, covered with borax, 

 to the action of a strong fire for an hour, and obtained a 

 white metal, in part fused, brittle, and of which a part was 

 still inclosed in the borax. To separate the whole of this 

 metal from the borax they reduced it to powder, and washed 

 it till the separation was complete. 



This metal, when thus purified, does not dissolve in any 

 simple acid. It combines with the nitro-muriatic acid, and 

 gives it a very dark red colour. This solution takes place 

 with more difficulty than that of pure platina, and requires 

 more acid. It loses its colour by sulphate of iron : with 

 prussiate of potash it gives a brown precipitate, which be- 

 comes green in the air : it communicates to a solution of 

 pure platina the property of precipitating it of a very dark 

 red colour by sal-ammoniac. 



Such are the properties which Fourcroy and Vauquelin. 

 found in this metal, and which they are inclined to think 

 do not belong to any of those hitherto known. 



We shall now give, in a few words, an account of some 

 of those experiments which they made on the different kinds 

 of triple salts formed by solutions of platina and sal-ammo- 

 niac, to ascertain the cause of their various shades. 



If a solution of crude platina in nitro-muriatic acid be 

 twice precipitated by sal-ammoniac, it almost always hap- 

 pens that the second precipitate is of a very dark red colour, 

 while the former is of a pale yellow or orange colour, and 

 the mother- waters of these two precipitates, when evapo- 

 rated, furnish more red. 



If the yellow precipitate, when washed, be reduced to 

 the metallic state by a sufficient heat, it does not dissolve 

 speedily and in large quantity in the nitro-muriatic acid 

 without leaving a sensible residuum : on the other hand, 

 the red precipitate, when treated in the same manner, dis- 

 solves with more difficulty and in less quantity in the nitro- 

 muriatic acid, and always leaves a black powder, more or 

 less absorbent, which, when washed and exposed to a strong 

 heat, is reduced to a metal having a perfect resemblance to 

 that which they discovered in the residuum of crude pla- 

 tina dissolved in aqua regia. The whole of this metal, 

 however, is not separated by the aqua regia of the platina, 



K 2 arising 



