RHODIUM. 4-61 



good many years ago, enabled me to determine 

 the atomic weight of rhodium and its oxides, 

 with considerable precision. This salt forms 

 rhomboidal crystals of an intensely deep red 

 colour, and not altered by exposure to the air. 

 It is insoluble in alcohol, but sufficiently so in 

 water. Carbonate of ammonia produces no ef- 

 fect upon the solution of this salt ; but caustic 

 ammonia, as well as the caustic fixed alkalies 

 precipitate the peroxide of rhodium in yellow 

 coloured flocks. An excess of the fixed alkalies 

 redissolves the whole of the precipitate. Though 

 ammonia does not act so powerfully as a solvent, 

 yet it is not without its effect ; for the whole 

 oxide of rhodium is never obtained if an excess 

 of ammonia be added to the solution. 



1. A hundred grains of crystals of soda mu- Analysis of 



r TIT- j soda-mu- 



riate of rhodium were dissolved in water, anciriateofrho- 



the peroxide was precipitated by ammonia, tak- 

 ing care not to add that alkali in excess. The 

 oxide of rhodium, when collected, washed, and 

 dried, was found to weigh 26*07 grains. 



Into a solution of another 100 grains of the 

 same salt a polished plate of zinc was put, and 

 left in the solution till the whole of the rhodium 

 which it contained had been precipitated in the 

 metallic state. To prevent the rhodium from 

 adhering to the zinc, which would have made it 

 difficult to weigh it correctly, the liquor had 

 been acidulated with some muriatic acid. The 



