Memoir upon Palladium and Rhodium. 43 



Fifteen grammes of this salt made red hot in an earthen cruci- 

 l)le furnished four grammes and two-tenths of white metal not 

 fused, hut all t!ie parts of which were agglutinated and formed 

 only one mass. In another experiment ten grammes of the same 

 salt gave three weak grammes of metal : from these results it is 

 evident that this salt contains between 28 and 29 per cent, of 

 metal. 



Being anxious to kno^v if this metal could he united with sul- 

 phur, and, in this case, how much it required to pass to the state 

 of a complete su!]3huret, I mixed four grammes of the above salt 

 with as much sulphur, and I heated this mixture for Some mi- 

 nutes in a furnace. I obtained a well fused metal of a blucish- 

 white colour, weighing one gramme -VfiV- 'This result proves 

 that the rhodium is combined with the sulphur ; without which 

 it would not have melted, and would have only yielded, accord- 

 ing to the proportion above estabiished, one gran)me -J^^ of 

 metal ; it had therefore acquired -,V'u"o ^^ sulphur, which is in 

 the ratio of 26 to -^ of metal. 



The sulpliuret of rhodium, when subjected to a strong heat 

 in contact with the air, exhales sulphurous acid, and exhibits 

 considerable arborisations. After this o]jeration, it is white, 

 spongy, and brittle, and does not u'eigh more than one gramme 







i " _ 



Fusibility. — Rhodium of all the known metals seems to be 

 the most infusible ; in fact, one semigramme of this metal, 

 coming from its submuriate, decomposed at a middling heat, 

 and which had on that account a blackish colour, heated for a 

 long time on a piece of charcoal upon which a stream of oxygen 

 gas played, was not melted : its parts were merely agglutinated 

 into a single mass, which was of a silvery-white colour. I re- 

 peated this operation several times on still smaller quantities, 

 without fusing them completely. This metal, although fragile, 

 is therefore more difficult to fuse than the pure j)latina and pal- 

 ladium, which melt very speedily in a fire kept up by oxygen gas. 

 Hence it was impossible to determine the specific gravity of this 

 metal. 



We may say therefore that pure rhodium is a metal of a 

 white colour, very little different from that of palladium, which 

 is brittle, and more difficult to fuse than all the other metals. 



§ XI. Soluhility of Rhodium in the Acid^. — One graiume of 

 rhodium in fine powder subjected to the action of eight grammes 

 of nitro-muriatic acid, in ecjual parts, was not sensibly attacked, 

 and scarcely was the acid coloured. I then treated it with a 

 very strong acid, but it vvas not dissolved. Since rhodium 

 when it is pure is absolutely insolulde in the acids, we must 

 suppose that it is alloyed in the ore of platina with other metals, 



which 



