iS 14.] On Palladium and Rhodium. 273 



The infusion of nutgalls produces no change in the solution of 

 palladium; but when a few drops of ammonia are added to the 

 mixture, a greenish precipitate falls, 'lhe liquid retains a yellow 

 colour, Which announces the action of ammonia on that combina- 

 tion. 



Muriate of tin forms a black precipitate when poured into the 

 solution of palladium. Green sulphate of iron throws it down in 

 the metallic state. 



When the oxide of palladium is separated from the acid by 

 means of potash, it retains a great deal of water, at leaet its volume 

 is very considerable. In this suite it has a reddish brown colour. 

 When dried its bulk diminishes greatly, and it acquires a very bril- 

 liant black colour. 



Muriate of palladium then does not form a triple salt with 

 potash, as i3 the case with muriate of platinum. 



The oxide of palladium, well washed, and dried as much as 

 possible in a gentle heat, loses 20 per cent, and becomes metallic. 

 Hence it contains a great deal of oxygen. 



VII. 

 Stdphuration of Palladium. 



A hundred parts of the rose-coloured triple salt of palladium, 

 heated with its own weight of sulphur in a covered crucible, fur- 

 nished 52 parts of a bluish white sulphufet, very hard, and when 

 broken exhibiting brilliant plates in its fracture. . 



Knowing from preceding experiments that 100 parts of the salt 

 contain from 40 to 42 of metal, it was easy to determine the quan- 

 tity of sulphur which had combined in the above experiment. It is 

 evident that if -12 of metal (the pioportion which I consider as 

 the most probable) absorb 10 of sulphur, 100 parts of palladium 

 would requite 21 of sulphur to convert them into a complete sul- 

 phuret. 



The sulphuret of palladium put into a cupel me'ted completely 

 at the temperature at which silver is assayed. When a certain 

 proportion of the sulphur was dissipated, the metal became solid, 

 increased in volume, and became rough on the surface. When the 

 whole sulphur was separated, the palladium was of a silver white 

 >ur. It flattened easily under the hammer, and could be passed 

 between rollers without cracking. 



Sometimes palladium obtained by limning oil" the sulphur pre- 

 sents on ii, surfs e ^><>tsof a greenish blu< colour, which seem to 

 • ;i: " i" n commencement of oxidation; for they disappear in 

 muriatic acid, while the acnl acquires a reddish colour. 'I lie same 

 thing happen! when, in decomposing the triple salt, heat enough is 

 not given to dri the oxygen completely. Platinum does not 



Bnite in this manner to sulphur. 



Vol. iv. n°.iv. a 



