W. Gibbs on the Platinum Metals. . 65 
Fremy’s* most recent method consists in roasting the ore 
in a current of air or oxygen at a strong red heat. Under 
these ienieusdiows the osmium is in a gr eat measure removed 
as osmic acid, while the other metals are more or less com- 
pletely oxydized. The mass from which the osmium has been 
removed is then to be fused with nitre, after which the re- 
maining osmium may be separated by distillation with nitrie 
acid. remy gives a method for the separation of the other 
a state of.purity. The separation of the osmium by roasting, 
has undoubtedly the advantage of giving pure osmie acid in 
rune not remove all the se and react does not ob- 
sorts ine fusion with nitre and caustic See n an eX- 
perisent "ahh I made to test Fremy’s process and in which I 
employed California ore in the form of fine gray sand and heated 
to full whiteness in a porcelain tube, I obtained after long heat- 
ing but little osmic acid; the tube became clogged and broke, 
and after cooling I found that a ore had actually melted and 
presented a gray mass, having the shape of the tube in which it 
was fused. This mass res embled when broken a fine grained 
cast iron; it was very hard and distinctly crystalline upon those 
parts of the fracture nearest the surface. As the large scales of 
osmiridium from California do not melt before the flame of the 
compound blowpipe this result was very unexpected; it was 
es owing to the large quantity of iron which the ore con- 
tai 
In a memoir published in 1835, Persozi} gave a method 6 
working osmiridium by first converting the metals into sulphide 
The ore is to be mixed with carbonate of soda and sulphur and 
then projected into a strongly heated earthen crucible. 
crucible is then ee be heated to mearnes, allowed to ae and 
€ treated with water to dissolve the alkaline salah 
Temaining mass heated with oxyd of mereury which os 
of iridiam—according to Persoz—while oxyd of osmium and 
metallic mercury are expelled. iz 
: * Comptes Rendus, Xxxviii, 1008. 
+ Ann. ong Chimie bogie ie race 55, 210. 
Au Jove. Sci—Srconp Sens, VoL. XXXI, No. 91—Jay., 1861. 
9 
