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XL. On Osmious Acid, and the position of Osmium in the list of 
Elements. By J. W. Mauer, Professor of Chemistry, §c., 
University of Alabama*. 
N most chemical text-books it is stated, on the authority of 
Berzelius, that there are five oxides of osmium—OsO, 
Os? 08, OsO?, OsO?, and OsO*—of which, however, the second 
and fourth have not been isolated, although compounds containing 
them are known. To these may be added a blue substance, 
first obtained by Vauquelin and supposed by Berzelius to con- 
sist of OsO united to either Os? O? or OsO?, and the highest 
oxide, probably OsO®, the existence of which was announced by 
Fremy in 1854. 
While preparing osmium from some black platinum residues, 
I have accidentally obtained a substance which there is some 
reason to believe may be osmious acid—the hitherto unisolated 
teroxide—mixed indeed with osmic acid, but still permitting cer- 
tain of its properties to be observed. 
Three or four ounces of the platinum residue were treated by 
a modification of the original process of Wollaston, now seldom 
adopted. The powder was mixed with three times its weight of 
nitre, the mixture was fused for some time in an iron crucible, 
and then poured out upon an iron plate. While still warm the 
fused cake was broken into fragments and put into a flask fitted 
with a cork, through which passed a tube two feet long, bent at 
right angles, and a funnel-tube, the latter drawn out to a very 
small bore at the lower end, and reaching to the bottom of the 
flask. The bent tube was well cooled, and ; undiluted oil of 
vitriol was very cautiously poured, by a few drops at a time, into 
the funnel. 
The acid produced intense heat on coming in contact with the 
cake of potash salt, and oily drops of a bright yellow colour began 
to make their appearance in the cooled tube. These drops very 
slowly congealed to a solid resembling unbleached bees-wax. 
By the time the sulphuric acid had been added in slight excess, 
a considerable quantity of this yellow substance had collected 
in the tube and in a receiver attached. By gently heating, the 
whole was obtained in the receiver, and united under a little 
water to a single mass. Towards the end of the distillation 
colourless needles and fused drops of the well-known osmic acid 
came over, and doubtless a considerable portion of the yellow 
mass in the receiver consisted of the same. 
At first it seemed probable that the yellow colour of the latter 
was due merely to some impurity, and it was therefore cautiously 
* From Silliman’s American Journal for January 1860. 
Phil. Mag, S. 4. Vol. 19, No. 127. April 1860. x 
