* 70 oe W. Gibbs on the Platinum Metals. 
Fee 
upon the lungs have not been exaggerated and too much care — 
cannot be taken to avoid inhaling 1 7 
The solution of alkaline salts contains only a portion of the — 
osmium in the ore. The other portion exists in the mixture of | 
oxyd and must be separated by distillation. For this purpose | 
the retort should be provided with a safety tube passing through — 
the tubulure and with a receiver kept cold, and connected by a 
wide bent tube with a series of two or three two-necked bottles 
containing a strong solution of caustic potash with a little alco- — 
hol and also kept cold. All the tubulures and connections must — 
made perfectly tight. Strong chlorhydric acid is then to be — 
cautiously poured into the retort through the safety-tube in small _ 
portions at atime. The reaction which ensues is often violent; — 
great heat is evolved and a portion of the osmic acid distils over _ 
immediately and condenses in the receiver in the form of color- 
less needles. When a large excess of acid has been added, the 
action has entirely ceased and the retort has become cold, heat 
may be applied by means of a sand bath. The osmic acid grad- 
thrown away as worthless. ee 
The dissolved portions drawn off from the retort have a very _ 
dark brown-red color. The solution is to be evaporated to dry- — 
ness, redissolved in hot water and again evaporated, after adding — 
Tocess 
a little chlorhydric acid, and this p repeated till no smell — 
of osmic acid can be perceived. A cold and saturated solution — 
of chlorid of potassium is then to be added in large excess, This — 
dissolves the chlorids of iron and palladium which may be pres- 
ent, leaving platinum, iridium, rhodium and ruthenium as double 
* chlorids insoluble in a strong solution of the alkaline chlorid. — 
