40 Memoir upon Palladium and Rhodium. 



more combustible. I fomid the spec' ic gravity of the laminated 

 palladium to be tvveUe and a veiy small fraction. 



§ VI. Solution of Pnliadium by the nifro-mvriaiic And. — 

 One gramme of palladium put into six granunes of uitro-muri- 

 atic acid composed of equal i:arts was speedily att».jked, even 

 in the cold way, which was announced by tiie rt Jdish-brown 

 colour assumed by the liquor. At first, no nitrous gas was de- 

 veloped ; but, by means of heat, plenty came over ; v'^'ch indi- 

 cates that palladium requires a great quantity of oxyyeu for its 

 solution. 



The solution of palladium is or a reddish brown, which is 

 deeper in proportion to the quantity cf acid v.hu !■ it ccniains ; 

 for, in propoition as the latter evaj)orateSj tlie colour diminishes, 

 and the solution gives a salt of a favr. colou) ainios.t insoi .'. ! , and 

 which merely makes the vvi'ter yellow ; but this so)u*iun becomes 

 reddi-'i brown on the addition of some drc-:s of muriatic acid. 



The neutral muriate of pallr.d'u;n is not very soluble in water; 

 it is dissoi*p(", on the contrary, abundantly when the water is 

 sharpened with a little muriatic acid. This solution is not re- 

 gularly crystallized. 



The muriate of ammonia in liquor, put into the acid solution 

 of palladium, forms no precipitate in it ; but if the liquors are 

 sufficiently tliick, there is im:nediateh" formed a great quantity 

 of crystals in needles of a greenisli-yelioA" colour and very sin- 

 gular. When the crystallization takes place slowly, this salt 

 presents the form of quadrilateral prisms or elongated hexa- 

 gons: these are the ammoniacal nnniate of palladium. If to 

 the solution of this triple salt we add some drops of ammonia in 

 order to saturate the excess of acid, a very brilliant crystalline 

 red precipitate is formed, which is the ammoniacal submuriate of 

 palladium above alluded to. 



The solution of potash turns the colour of the muriate of 

 palladium brown, and separates from it red and brilliant flakes, 

 as if they were formed of laminae : the liquor remains coloured, 

 notwithstanding the excess of alkali ; but heat affects the pre- 

 cipitation of the oxide of palladium, and the liquor loses its co- 

 lour entirely: the alkaline carbonates produce the same effect. 



The infusion of gall-nuts produces no change in the solution 

 of palladium ; the addition of some drops of ammonia to this 

 mixture determines a greenish precipitate: the liquor contiimes 

 <4f a yellow colour j which announces an action of ammonia on 

 this combination. The muriate of tin at the minimum forms 

 in the solution of })aliadium a black precipitate. The green 

 sulphate of iron precipitates it in the metallic state. 



The oxide of pa'ladium, on being separated from the acid by 

 means of potaeb^ retains much water, at least it occupies a 



great 



