On some Comlinaiions of Platina: 351 



florence flask. — When the hydrosulphuret of platina is 

 treated with strong nitrous acid, an immediate action takes 

 place, heat is excued, the acid is decomposed, nitrous gas 

 is evolved, and sulphuric acid formed. The spontaneous 

 action, however, is very limited, and soon subsides ; heat 

 must now be applied, and the materials boiled to dryness. 

 When the excess of nitrous acid is expelled, a httle more 

 should be added, to insure the entire conversion of the 

 hydrosulphuret into sulphate. The utmost heat of a large 

 Argand's lamp may now be applied for a considerable time. 

 When the superabundant acid is driven off, and no more 

 fumes can be perceived, the sulphate of platina alone re- 

 mains, and exhibits the following properties. 



Phyikal and Chemical Properties. 



Its colour is very dark brown, approaching to black. It 

 is obtained in the form of a porous crust or cake, resembling 

 a dry cinder, or the carbonaceous matter resulting from 

 the decomposition of sugar by heat. It is very brittle, and 

 easily pulverized. It has a brilliant resinous lustre, some- 

 what analogous to crystallized blende, and the powder 

 exhibits a crranular appearance. — Its taste is rather acid and 

 nietallic, w°ith some degree of causticity. — It slightly affects 

 litmus paper. It is very deliquescent, and, of course, readily 

 soluble in water. When exposed in a dry state to the 

 atmosphere for a few minutes, it becornes quite moist, and 

 after a short time assumes the fluid form. — In this state 

 it appears as a dark brown viscid sulistance, and a single 

 drop of it colours about a gallon of water. The dry sul- 

 phate is soluble in alcohol, and in ether. It is soluble in 

 muriatic acid. When it is boiled to dryness in this acid 

 and heated, it is decompounded, the sulphuric acid is ex- 

 pelled, and the insoluble compound of platina and chlorine 

 remains. It is soluble in nitric acid ; but this acid may be 

 successively boiled to dryness on it, without apparently 

 altering its'conslitution. It is soluble in phosphoric acid, — 

 When°hc aqueous solution of sulphate of platina is treated 

 with pure potash, soda or ammonia, peculiar triple com- 

 pounds are formed. — Muriate of alumine, and muriate of 

 barytes, also produce peculiar compoinids with sulphate of 

 platina. Of these alkalme and earthy substances, more 

 will be said hereafter. 



I have not obtained the sulphate of platina in a perFcctly 

 crystallized state. 1 made some slight attempts of this 

 kind, but have not succeeded in determining the form of 

 the crystals. 



