216 On Palladium and Rhodium, [Seit, 



Article IX. 

 Memoir on Palladium and Rhodium. By M. Vauquelin.* 



I. Palladium. 



Historical Sketch of the Facts hitherto ascertained respecting Pal- 

 ladium. 



In the month of April, 1 803, a printed note was circulated in 

 London, stating that a new metal resembling silver was sold by 

 Mrs. Forster, Gerrard -street, under the name of palladium, or nevy 

 silver. The following properties of the metal were announced in 

 the printed note: — 



1. It is soluble in nitric acid, and gives a solution of a deep red. 



2. Sulphate of iron precipitates it from that solution, as it does 

 gold from nitromuriatic acid. 



3. If the solution be evaporated, we obtain a red oxide, which is 

 soluble in muriatic acid, and other acids. 



4. It is precipitated by mercury, and by all the other metals, 

 excepting gold, platinum, and silver. 



5. Its specific gravity, when hammered, is only 113; but after 

 being rolled out, it is 1 1*8. 



6. Its surface becomes tarnished by an ordinaiy red heat, and it 

 acquires a blue colour ; but it recovers its brilliancy when violently 

 heated, as is the case with the other noble metals. 



7- The strongest heat of a forge is scarcely sufficient to melt it ; 

 but if a little sulphur be added to it while hot, it melts, and flows 

 as readily as zinc. 



Mr. Chenevix, who was one of the first that received this printed 

 notice, suspecting, from the odd manner of publishing so interest- 

 ing a discovery, without the name of the author, some error or 

 imposition, immediately procured a quantity of the metal. 



After having recognised in it the characters that had been 

 assigned, Mr. Chenevix, satisfied that it did not resemble any 

 known metal, engaged in a laborious set of analytical and syn- 

 thetical experiments on the subject ; the result of which he com- 

 municated to the Royal Society, on the 12th of Ma)', 1803. 



These researches led the author to conclude that palladium was a 

 compound of platinum and mercury 3 for having obtained palladium 

 by precipitating a mixture of the solutions of platinum and mercury 

 by sulphate of iron, he took it for granted that he had formed it. 

 But there can be no doubt, from what we know of the subject at 

 present, that all the palladium which he obtained had been con- 

 tained in the platinum solution. 



Dr. Wollaston, by examining the solution of platinum, found in 



1 Translated from ehe Ann. de Chiin. toI. Ixxxriii. p. 167, for Not, 1813. 



