PLATINOUS COMPOUNDS. 683 



cipitate, when the protochloride of platinum is decomposed by 

 sulphuretted hydrogen. It may be washed and dried without 

 decomposition. 



Protochloride of platinum, Pfc Cl, is obtained by evaporating a 

 solution of the bichloride of platinum to dryness ; triturating the 

 dry mass and heating it in a porcelain capsule, by a sand bath 

 at the melting point of tin, taking care to stir it, at the same 

 time, so long as chlorine is evolved. It remains as a greenish 

 grey powder, quite insoluble in water, and repelling that liquid 

 so as not to be moistened by it. This chloride is not decom- 

 posed by sulphuric or nitric acid, but is partially soluble in 

 boiling and concentrated hydrochloric acid. From the last 

 solution, alkalies throw down a black precipitate of protoxide. 

 When the calcination of the bichloride of platinum, at 420 or 

 460, is interrupted before the whole chlorine is expelled, the 

 residue gives to water a compound of a brown colour, so deep, 

 that the liquid becomes opaque. This, Professor Magnus 

 believes to be a combination of the two chlorides of platinum. 

 A double protochloride of platinum and potassium, PtCl + KC1 

 is obtained on adding chloride of potassium to the solution 

 of the platinous chloride in hydrochloric acid, and evaporating 

 the liquid. The salt crystallizes in four sided red prisms, of 

 which the form is the same as a corresponding salt of palladium ; 

 it is anhydrous. A protochloride of platinum and sodium also 

 exists, but does not crystallize easily. 



Ammoniacal protochloride of platinum, PtCl-hNH 3 , was 

 obtained by Magnus, on adding solution of ammonia to the 

 double protochloride of platinum and ammonium. A green 

 salt precipitates after a time, which is entirely crystalline, 

 insoluble in water, alcohol, hydrochloric acid and ammonia. 



The green crystalline salt of Magnus is not decomposed or 

 dissolved by boiling alkalies, nor by boiling sulphuric or hydro- 

 chloric acid ; so that the ammonia or its elements are in an 

 unusal state of combination. M. J. Gros, of Wesserling, has 

 formed a singular class of compounds from it. When treated 

 with hot concentrated nitric acid, the green salt is converted 

 into a white crystalline powder, which dissolves easily in water, 

 leaving half the platinum in the metallic state. The white salt is 

 obtained by a second crystallization in flat prisms ; it is named 

 nitrate of the chloramide of platinum by Liebig. Neither the 

 chlorine nor the platinum contained in this salt is precipitated 



