1839.] 



On Chemical Tesfs. 



331 



fected by chalk, or by pure magnesia. The solution with lime gives 

 a deep red precipitate with galls which turns blue by acids. Osmium 

 heated in the air, and in distillation, has an odour somewhat like chlo- 

 rine. If a very small piece of pure osmium be placed on a slip of pla- 

 tina foil near its edge, and be brought into the flame of burning spirits 

 of wine, and be held so as to allow a portion of the flame to rise freely 

 by the side of the platinum the flame becomes suddenly very brilliant 

 just as if pure olefiant gas had been inflamed. 



94. OXYGEN GAS in water detected, see 67. 



95. PALLADIUM. Mercury, as well as protosulphate of iron throws 

 down palladium in a metallic form : cyanuret of mercury separates it 

 in the form of a yellowish white precipitate [cyanuret of palladium] but 

 the solution of palladium must in this case be neutral. This precipitate 

 detonates when heated. Palladium forms a red solution with nitric 

 acid, and precipitates in a brown powder on adding protomuriate of tin ; 

 but if the solution be much diluted this re-agent produces a fine emerald 

 green colour. Prussiate of potash produces an olive coloured precipi- 

 tate ; sulphuretted hydrogen a dark brown; and all the metals except 

 gold, or silver, and platina precipitate metallic palladium. The alkalies 

 occasion an orange coloured precipitate. 



«. Almost all the salts of palladium are soluble in water, and the 

 colour of the solutions is a fine red. 



96. PLATINA. Platinum in solution which is generally 

 brown, or yellowish brown is detected by muriate of ammonia, see 

 34, and by protomuriate of tin, which is a delicate test, and produces 

 an orange coloured precipitate (Accum), see 122. Protochloride of tin 

 communicates to solutions of chloride of platinum a deep reddish brown 

 colour without producing a precipitate (Rose). Potash and ammonia 

 and their carbonates produce yellow precipitates of chloride of the test 

 and platinum. Prussiate of potash changes the colour from yellow to 

 green 



The following tests give further indications of platinum. 



Potash and ammonia and their carbonates produce yellow precipitates 

 as before mentioned, particularly when muriatic acid is added to the 

 solution. These precipitates are not soluble in free acid; but those by 

 potash and ammonia are soluble in an excess of those alkalies, when 

 they are heated ; and if the solution is afterwards supersaturated with 

 muriatic acid a white precipitate is produced. 



