Fusion of Iridium and Rhodium. 369 
simultaneous presence of oxygen. and the most intense heat. It 
might be fused by exposure in vacuo to the discharge of a pow- 
erful voltaic series, by means of the apparatus of which a descrip- 
tion with engravings has been. given in a recent volume of the 
Transactions of the American Philosophical Society, and ae 
lished in this Journal for 1841, vol. xl, p. 303. 
_Thave obtained osmium by honing the osmiate of ammonia in 
a glass tube with sal. ammoniac, agreeably to the instructions 
given by Berzelius. In this way a result was obtained which 
the information given by that distinguished chemist, had not led 
me to anticipate. 'The tube became coated with a ring of osmi- 
um, which it would be impossible by inspection merely, to dis- 
tinguish from the arsenical ring on the peculiar features of which, 
reliance has been placed for the detection of arsenic. 
~ It follows from my experiments and observations, that of all 
metallic bodies, osmiuret of iridium is the most difficult to fuse ; 
_ that rhodium and iridium are both fusible by the hydro-oxygen 
blowpipe, properly employed ; that the former has the rosy white- 
hess of bismuth, the latter the pale white of antimony ; and that 
both of them are slightly sectile though. extremely hard and near- 
ly unmalleable; that iridium merely fused, is | than platinum 
condensed by the hammer. —'Thus it follows from my experiments 
and from the recent observations of Breithaupt, on some specimens 
of native iridium, that the metal whether in this state or pure as 
obtained by chemical skill and. consolidated by fusion, must be 
allowed that preéminence in density which, until of late, was 
given to platinum. 
_ Itmay be proper to add that subsequently to the writing of the 
preceding narrative, receiving some large quantities of iridium and 
thodium, from Johnson and Cocke, my experiments were success- 
fully repeated on a larger scale, but without any result besides 
that of confirming the facts above stated. 
Srconp Srnizs, Vol. II, No. 6.—Nor., 1846. ae 48 
