Experiments on the Oxide and Salts of Uranium. — 87 
by copper, their solution was therefore decomposed by excess of 
ammonia, and the precipitated oxide digested in liquid ammo- 
nia, until all traces of copper were removed; it was then 
washed, and dried in a very moderate heat, and was considered 
as a pure hydrated peroxide of uranium. ; 
But this supposed peroxide dissolved very readily in muri- 
atic acid, without the slightest evolution of chlorine, though 
there was some effervescence arising from the extrieation of a 
small portion of carbonic acid gas. Moreover, the above hy- 
drated oxide, when heated to dull redness in a glass tube, only 
lost water and a little carbonic acid; it lost no oxygen, but 
became black and cohesive, diminishing exceedingly in bulk. 
A portion heated to bright redness in a platinum crucible, 
underwent nearly the same changes, contracting into a dark 
purplish mass, which, however, when triturated into an im- 
palpable powder in an agate mortar, assumed a dingy yellow- 
brown tint. In this state the oxide of uranium appears only to 
lose water and a small portion of carbonic acid, accidentally 
contracted during its precipitation and drying, and not to have 
altered its state of oxidation, for it remains as before, perfectly 
soluble in muriatic and nitric acids, evolving no gas, and form- 
ing salts in no respect differing from those produced with the 
hydrated oxide, recently thrown down from the nitrate. 
50 grs. of the yellow hydrated oxide of uranium, dried at 212° 
and afterwards exposed under the exhausted receiver including 
a surface of sulphuric acid, till it no longer lost weight, were 
exposed to a white heat, in a platinum capsule. The loss, upon 
an average of three trials, amounted to 6 grains, so that the 
composition of the hydrated oxide of uranium is— 
88 oxide 
12 water 
100 
and, assuming this hydrate to consist of 1 proportional of water 
and 1 of oxide, the prime equivalent of oxide of uranium will 
be 66, that of water being 9; and 58 will be the equivalent of 
uranium, if the above oxide be a compound of | proportional 
of metal and 1 of oxygen. 
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