W. Gibbs on the Platinum Metals. 63 
ArT. VIT.—Researches on the Platinum Metals; by Wo.corr 
Gipss, M.D., Prof. of Chemistry and Physics in the Free 
Academy, New York. 
Reprinted by permission from the Contrib. of the Smithsonian Institution, Vol. XII. 
ie 
THE material which formed the subject of the present investi- 
gation was chiefly obtained from the United States Assay Office 
and from the Philadelphia Mint, and I am indebted for it to the 
kindness of Dr. Torrey and of Prof. Bache. Messrs. Cornelius 
of Philadelphia have also liberally presented me with about 600 
grammes of the Siberian osmiridium—a supply which has been 
of great assistance and for which I desire to express my thanks. 
The samples obtained from the mint at different times and which 
had been subjected to different preliminary processes, varied 
greatly in appearance. In some cases the ore was in distin 
scales rather whiter than the Siberian osmiridium ; in a sample 
weight of silver and the osmiridium allowed to settle. When 
the gol lloy is poured off, there remains a mass containing 
nearly all the osmiridium mixed with gold. This mass is fused 
in it shall create a deman 
* Dr. Torrey has kindly furnished me 
osmiridium, “For the first year or. 
whenever important Dee applications of the met 
