1818.] the Commencement of the Year 1817. Part I. 29 



some experiments on the salts of platinum ; and every thine 

 coming from a chemist of such experience is entitled to attention. 

 When common muriate of platinum i3 exposed to a heat suffi- 

 cient to drive off a portion of its acid, chlorine is disengaged, 

 and the salt acquires a fawn-brown colour, and loses its taste and. 

 its solubility ; and when 100 parts of it are exposed to a strong 

 heat, they leave 72-5 parts of metallic platinum. Two opinions 

 may be entertained respecting - the nature of this brown residue. 

 1. It may be a chloride of platinum; on which supposition it 

 would be a compound of 



Chlorine 27-5 4-5 



Platinum . . 725 11-863 



100-0 



2. It may be a compound of muriatic acid and oxide of plati- 

 num. This is the opinion entertained by Vauquelin. If we 

 suppose the oxygen in the oxide, as seems to follow from Vau- 

 quelin's experiments, to be a compound of 



Platinum 84 



Oxygen 16 



100 



then the oxide of platinum in this salt must amount to 86-3, and 

 of course it must be a compound of 



Muriatic acid 13-7 4-625 9-250 



Oxide of platinum. . . 86-3 29-134 14-567 



100-0 



This last supposition would make the weight of an atom of 

 platinum 12-567 if we consider the oxide to contain two atoms 

 of oxygen. For my own part I think it most probable that the 

 fawn-coloured powder obtained from the muriate is rather a 

 chloride than a submuriate. 



When a solution of muriate of platinum, as neutral as possible, 

 is mixed with the requisite proportion of common salt, a triple 

 salt is formed which crystallizes with facility in fine crystals of a 

 beautiful orange red. ii' instead of common salt, caustic soda 

 be added in such a proportion as not to be in excess, the liquid 

 becomes of a dark brown colour, and nothing precipitates. If 

 this liquid be allowed to evaporate spontaneously, yellowish 

 brown crystals are obtained, forming plates like mica, among 

 which some may be perceived of a pearl-grey colour, and very 

 brilliant. These crystals art,' perfectly neutral. They are very 

 soluble in water, do not deliquesce, and the solution has a deep 

 brown colour. Sal-ammoniac occasions in it a precipitate of a 

 greenish yellow colour, and the mother water preserves its brown 

 colour ; but when sal-ammoniac is dropped into the salt, made 



