On, some Comhinations of Platina. 277 



t'he boiling continued to dryness. The mass was now 

 heated just below redness in a platina crucible. It acquired 

 an olive colour, and resembled platinana. It was heated 

 withflowersof sulphur in a small retort over distilled water, 

 and afforded sulphuret of platina and sulphuvane, which 

 last flowed in drops into the water : it was partially decom- 

 pounded, and occasioned no precipitate with muriate of 

 barvtes, but a copious one with nitrate of silver. 



From these experiments I must conclude, that no sub- 

 nitrate, or insoluble sulphate of platina, can be obtained by 

 the preceding methods ; nor are any such compounds at 

 present known to exist. The insoluble muriat of Mr. 

 Chenevix was, I presume, a mixed compound of plalinane 

 and platinana with water. I feel a reluctance in makmg 

 these and the preceding statements, becau>e they are op- 

 posed to those of Mr. Chenevix. It would have been much 

 more agreeable to me, to have confirmed his general results. 

 I am convinced this ingenious chemist must have been 

 misled by some circumstances connected with his experi- 

 ments. 



M. Tromsdorf* states that oxide of platina combines 

 with benzoic acid, and forms a yellow-coloured salt. I have 

 not seen the details of his experiments; but as the oxides of 

 platina appear to be unknown in a separate state, and it is 

 extremely difficult to detach chlorine or the alkalies fronrj 

 platina, I must regard the existence of this salt as extremely 

 doubtful. Bergman speaks of a combination of the calx 

 of plalina with the acid of sngarf. The calx he employed 

 was obtained from a solution of platina by soda. This sub- 

 stance is not an oxide of platina, as has been supposed. Alter 

 being dried, it furnishes a little oxygen by heat, and a sub- 

 stance analogous to platinana with muriate of soda. Hence, 

 there can be little doubt but that this oxalate of plaiina is 

 in facta triple compound of this kind, with a httleot the acid. 



Dr. Thomson speaks of a soluble prussiate of platina t. 

 1 have not been able to gain any evidence of the existence 

 of this salt. Schcele found that prussic acid had no effect 

 on plalina, or on those substances which were then con- 

 sidered as calxes of this metal. Bergman slates that 

 prussiate of potash occasions no precipitate in solutions of 

 platina, and Mr. Chenevix and Dr. Thomson assert that 

 platina is not precipitated by the prussiates. As a concen- 

 trated solution of muriate of platina appears to be a very 



• Annalts de Chlmif,tome xi. p. 315. 



f Physical and Chemical Ess:iy», vol. i. p. .'522. 



X Syttera of Chemistry, vol. iii. p. 131. 



S 3 good 



