J. W. Mallet on Osmious Acid. 49 
ever be undertaken, as has been proposed, to measure an exten- 
sive are of the equator, the idea of such a visual method for the 
accurate determination of the differences of longitude, would be 
. 
well worth considering. 
prism and signal wheel, might be done with considerable accu- 
station to the first. 
Art. VI.—On Osmious Acid, and the position of Osmium in the 
list of Elements; by J. W. Mauuet, Prof. of Chemistry, &c., 
Univ. of Alabama. | 
IN most chemical text-books it is stated, on the authority of 
Berzelius, that there are five oxyds of osmium—OsO, Os,0,, 
0s0,, O30,, 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, 
oxyd, probably OsO,, the existence of which was announce 
by Frémy in 1854 
teroxyd—mixed indeed with osmic acid, but still permitting cer- 
tain of its properties to be observed. 
ree or four ounces of the platinum residue were treated by 
4 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 
used cake was broken into fragments and put into a flask fitted 
with a cork, through which passed a tube two feet long, bent at 
Tight 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 vit- 
Tol 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 color began 
to make their appearance in the cooled tube. These drops very 
slowly congealed to a solid resembling unbleached bees-wax. 
SECOND SERIES, Vor. XXIX, No. 85.—JAN., 1960. 
7 
