366 Fusion of Iridium and Rhodium. 
was fused in the presence of Mr. Booth. Subsequently I procu- 
red specimens, warranted pure, severally from the house of Pelle- 
tier at Paris, and from Messrs. Johnson & Cocke, London. An- 
other specimen was given to me by a friend, who had received it 
as pure, from a source on which reliance may be placed ; and last- 
ly, I obtained myself, by Wohler’s process, a specimen of about 
sixty grains, from the insoluble residue of platinum ore. All the 
specimens thus procured, were found to be fusible under my hy- 
dro-oxygen blowpipe. The specimen obtained from Johnson & 
Cocke, after repeated fusions by which it was much consolidated, 
weighed sixty-seven grains. During fusion there appeared to be 
an escape of volatile matter, supposed to be osmic acid, arising 
from the presence of a minute portion of that metal, between 
which and iridium, an affinity of a peculiar degree of energy ex- 
ists. At acertain point of the process, a reaction took place sufli- 
ciently explosive to throw a portion of the metal, in globules, off 
from the support. One of these, about twice as large as the head 
of a common brass pin, proved to be hollow. By prolonged and 
repeated fusion, _ metal became more cn cieke and more 5 
sible. 
- Fused iridium has nearly the grain of soft cast steel, with the 
pale whiteness of antimony, and appears to be susceptible of a 
fine polish. Although as hard as untempered steel, it is some- 
what sectile, since when split by means of a cold chisel, the 
edge penetrated about the eighth of an inch before a division was 
effected. By light hammering a corner was flattened without 
fracture, although under heavier blows the mass cracked. I infer 
that sithoash nearly unmalleable and very hard, iridium may be 
wrought in the lathe. 
I have already mentioned that.I fused into a globule a speci 
men of iridium, obtained by me from the insoluble residuum of pla- 
tinum ore by Wohler’s process. From this globule, while congeal- 
ing, a portion ran out from the inside, leaving a cavity and cov- 
ering one of its sides externally with an incrustation, among 
which erystalline spangles, or facets, were discernible. ‘The spe- 
cific gravity of the globule of iridium, from the specimen fur- 
nished by Messrs. Johnson & Cocke, was taken by Mr. T. R- 
Eckfelt, of the United States mint at Philadelphia and by Dr. 
Boyé, both having balances of the greatest accuracy and 
ing very skillful in the employment of them. In the first in- 
