Memoir upon Palladium and Rhodium. 39 



agreeable red colour. In this respect it deserves the name of 

 rhodium rather than palladium. When we examine this salt 

 in the mass, it is formed of flexible brilliant and slender needles ; 

 when taken in the mass, they are s])ongy and soft to the touch. 



Reduction. Twenty grammes of this salt dry, and made red 

 hot in a forge in an earthen crucible, furnished eight grammes 

 or 40 per cent, of metal of a dead silver white, the particles of 

 which were united, but incompletely fused. This metal was 

 perfectly ductile and malleable. 



In order to observe more closely what passes during the de- 

 composition by fire of this salt of palladium, I heated some by the 

 blow-pi])e, and I saw that it fuses, diminishes greatly in volume, 

 and sends out vapours of nuiriate of ammonia and oxy-muriatic 

 acid. It is the fusion and diminution in volume of this salt 

 when heated, which, bringing more closely together the particles 

 of the metal, render it susceptible of being laminated. 



Solubility. The red salt of palladium is scarcely soluble in 

 water ; it merely communicates to it after a long contact a 

 slight yellow tinge. It is easily dissolved in weak muriatic acid 

 cold ; but at a boiling heat it dissolves completely : the solution 

 is of a yellowish brown. 



The excess of muriatic acid in this solution being saturated 

 with ammonia, the salt is precipitated with its red colour and 

 all its other pro|)erties: if we add an excess of alkali, the liquor 

 assumes a weak yellow colour. 



If, instead of ammonia, potash be employed to saturate the 

 excess of muriatic acid, the salt is precipitated in yellow flakes ; 

 but by adding ammonia afterwards thev become still more yellow j 

 which proves that they are combined once more with the am- 

 monia in the state of a triple salt. 



§ V. Some Properties of Palladium. — This metal has some 

 resemblance to platina, in its colour, malleability, hardness and 

 fusibility. 



The fire of our furnaces does not fuse it completely: I could 

 fuse it but imperfectly on a piece of lighted charcoal acted upon 

 by a jet of oxygen gas*. 



I have remarked that, when it is once fused, if we continue to 

 heat it in the same way, it boils and burns away in verv brilliant 

 sparks. A portion of the metal which has escaped from the 

 combustion is condensed on the surface of the piece of coal, in 

 the form of very small grains. 



Platina when fused in the same maniier does not burn like 

 palladium; which proves that the latter is more volatile and 



* M. Clienevix says tliut palladium melts in a common furnace: it is 

 probaMc, however, that wliat he subjected to this proof was not perfectly 

 pure. 



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