38* Intelligence and Miscellaneous Articles. 



and possesses peculiar properties ; but he lias not remarked that 

 his acid was an exception to the general rule. — Ann. de Chim. ct de 

 Phys. tom.li. p. 187. 



ON THE IODIDES OF "PLATINA AND THEIR COMPOUNDS. 

 BY M. LASSAIGNE. 



This paper has already been slightly noticed (Lond.and Edinb. 

 Phil. Mag., vol. ii. p. 197.): we shall now give a further account of 

 its contents. 



Protiodide of Platina.— Protochloride of platina was prepared by 

 first obtaining a solution of the perchloride by dissolving the metal 

 in aqua regia : this was evaporated to dryness. The perchloride ob- 

 tained was gently heated in a porcelain capsule till it ceased to dis- 

 engage chlorine : the resulting protochloride was of a yellowish 

 green colour. Any perchloride which might remain was gently 

 heated in alcohol of specific gravity '827 : a yellow coloured solu- 

 tion of perchloride was obtained by repeated washings. 



The purified protochloride was treated with a moderately strong 

 solution of iodide of potassium. No action occurred till the mixture 

 had been heated for about a quarter of an hour ; decomposition then 

 gradually took place, and a precipitate was obtained of the following 

 properties : it was black, heavy, finely divided, and adhered to the 

 fingers like charcoal ; it had neither taste nor smell. Neither water 

 nor alcohol acted upon it at any temperature, and it was unalterable 

 in the air. When heated it was decomposed, vapour of iodine 

 rising and spongy platina remaining. It may be heated to above 

 482° Fahr. without decomposing, but the vapour of iodine begins 

 to rise at about the temperature of boiling mercury. 



Neither nitric, sulphuric, nor muriatic acid has any action upon 

 it either hot or cold: the solution of potash or of soda gradually 

 decomposes it, and converts it into protoxide of platina, part of 

 which precipitates in the form of a black powder, and the rest re- 

 mains in solution in the excess of alkali with the subiodide formed. 

 Ammonia, digested in this iodide, gradually converts it at common 

 temperatures into a dull yellowish green matter ; this, after washing 

 and drying, is decomposed by heat, yielding ammonia, iodine, io- 

 duretted hydriodate of ammonia, and platina. It was found to be a 

 compound of protoxide of platina and iodide of platina, and ammo- 

 nia. The protiodide of platina decomposed by heat gave as the 

 mean of two experiments 



Iodine .. 5605 

 Platina.. 43'95 



10000. 

 A compound of 1 atom of iodine = 126 -f- 1 atom platina = 96 

 would consist of 



Iodine .. 56*76 

 Platina.. 43-24 



i 00-00. 



