Memoir upon Palladium and Rhodium. 4\ 



great deal of room : in this state it is of a reddish-brown co- 

 lour : on drynig it loses its volume, and takes on a very brilliant 

 black colour. 



The muriate of palladium does not form, therefore, triple salt 

 with potash like the muriate of platina. The oxide of palla- 

 dium, when well washed and dried as well as possible by a gentle 

 heat, loses 20 per cent, and becomes metallic: it contains there- 

 fore abundance of oxygen. 



§ VII. Sidphuration of Palladium. — One hundred parts of 

 the triple red salt of palladium, when heated with as much sul- 

 phur, in a well covered crucible, furnished 52 parts of a blueish 

 white sulphuret very hard, and presenting brilliant laminae in its 

 fracture. 



Being aware, from anterior experiments, that 100 parts of this 

 triple salt contain from 40 to 42 of metal, it was easy to know 

 the quraitity of sulphur which is combined with it in the above 

 operation. 



In fact, if 42 parts of metal (the result which I regard as the 

 most probable) absorb ten of sulphur, it is evident that 100 parts 

 of palladium will absorb about twenty-four in order to be sul- 

 phuretted completely. 



The sulphuret of palladium, when put into a cupel, is perfectly 

 fused at the heat at which assays of silver are made : when a 

 certain quantity of sulphur was dissipated, the metal was fixed, 

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

 all the sulphur was separated, the palladium was of a silver 

 Avhite ; it was malleable under the hammer, and might afterwards 

 pass through the rolling-press without being torn. 



Sometimes the palladium obtained by the roasting of its 

 suljjhuret, presents at its surface spots of a blueish-grecn colour, 

 which appear to be owing to a commencement of oxidation ; tor 

 they disappear in the muriatic acid, and tlie latter becomes of 

 a reddish colour. The same thing happens to it, when, by de- 

 composing its triple salt, a sufficient degree of heat is not given 

 to set the oxygen entirely free. The platina is not even united 

 to the sulphur. 



§ VIII. Rhodium. Examination of the ammoniacal Mu- 

 riate of Rhodium. — After having separated the palladium, and 

 evaporated the liquor containing the muriate of rhodium, in 

 order to obtain this crystallized salt, the mother-water was de- 

 canted, the crystals drained, and washed several times with al- 

 cohol as above described. This liquid dissolves the green met- 

 ter which exists among the crystals, and these last as§urae a 

 lively ruby-red colour. This salt, in order to be redissolved, re- 

 rpiircs much more water than before, because the alcohol ha,s 



taken 



