PLATINUM METALS AND ORE. 113 



5. RUTHENIUM. Still more infusible than the pre- 

 ceding metals. Sp. gr. = 11.3. Brittle. Pulverized and 

 heated in the air it is oxidized, fused with hydrate of 

 potassa and saltpetre or chlorate of potassa, it forms 

 ruthenite of potassa, KO, Ru O 3 , forming with water 

 a yellow solution. Neutralize this solution with nitric 

 acid, and a black sesquioxide is thrown down, which 

 is easily reduced in hydrogen gas. The double chlo- 

 ride of ruthenium and potassium, KCl-f Ru Cl 2 is easily 

 soluble in water, but insoluble in alcohol. The red 

 solution is not precipitated by potassa and alcohol in 

 the cold. If a stream of chlorine gas is conducted into 

 a solution of ruthenite of potassa ruthenic acid is ob- 

 tained, which is very volatile, of a yellow color, with 

 a strong odor, difficultly soluble in water, and soon 

 changing to black. 



6. OSMIUM. This metal alone is infusible in the 

 strongest oxy hydrogen flame, but forms a bluish me- 

 tallic mass with sp. gr. = 21.4 It volatilizes at the 

 highest temperature. It is obtained with all these 

 properties, if sulphide of osmium is heated in a strong 

 coke fire, in a close covered graphite crucible. It may 

 be prepared in the crystalline form by fusing the pul- 

 verized osmium with six or eight times its weight of 

 tin in a graphite crucible, slowly cooled, and the tin 

 dissolved by hydrochloric acid. Or it is obtained as 

 a bluish-black powder mass, when chloride of ammo- 

 nium is added to a solution of osmiate of potassa or 

 ammonia, evaporated to dry ness, and the mass heated 

 in a porcelain retort until the chloride of ammonium 

 begins to volatilize ; heating this with water, the osmium 



remains. 



rn 



The smallest quantity of osmium on platinum foil, 

 held in the flame of a spirit lamp, becomes brilliant, 

 and imparts the characteristic odor of osmic acid. 

 Osmium, heated in a slow stream of oxygen,- forms 

 osmic acid. It is also formed by oxidizing with nitric 



10* 



