i aoe W. Gibbs on the Platinum Metals. 
Weiss and Doebereiner* confirmed the results of Persoz so far | 
as the conversion of the platinum metals into sulphids was con- 
cerned. They recommended the fusion of the sulphids, after re- 
moving those of sodium and of iron by washing with water and 
chlorhydrie acid, with carbonate of potash and saltpetre, so as — 
to oxydize the sulphur and the platinum metals at the same time. 
By this process the ore is almost completely resolved in two ope- 
rations. 
On repeating these experiments with the California ore, I ob- — 
tained the same results as to the formation of the metallic sul- 
phids. After digesting the fused matter with chlorhydric acid 
and washing, there remained a greyish mass of crystalline scales, 
: a “ieee saa 
which resisted even boiling nitro-muriatic acid,—no s of 
osmic acid being perceptible. These scales were however pow- 
with oxydizing agents may however be readily overcome by — 
previously reducing them to the metallic state. This is mostsim- — 
ply accomplished by a method suggested to me by Dr. Genth, — 
which consists in evaporating the sulphids to dryness with a — 
small excess of strong sulphuric acid and then igniting gently. _ 
A gray metallic sponge remains, which contains all the platinum 
metals with a small quantity of iron. It is easily reduced to a — 
fine ee by rubbing in a mortar and may then be completely — 
oxydized by Claus’ method presently to be described. Nitro- — 
muriatic acid acts very slightly upon this metallic mixture and — 
I have not found it possible by this agent to remove an appreck 
“ trace of platinum. . 
the materials are heated together. The danger may be avoided — 
by fusing the nitre and potash together and, after all frothing has — 
ceased, projecting the metallic sponge little by little into the eru- 
cible, waiting in each case until the resulting action has ceased — 
before projecting a fresh portion. I am of opinion that the pre- 
* Annalen der Pharmacie, xiv, 15. 
