Experiments on the Oxide and Salts of Uranium. 89 
in the nitrate, dried as above described, for it is probable that 
in that state the salt still retains a portion of water, which 
would vitiate the above estimate. 
IV. When recently precipitated oxide of uranium is digested 
in sulphuric acid, diluted with 4 or 5 parts of water, a solution 
of a green colour is obtained, which has an astringent aluminous 
taste, and is neutral; but, when evaporated, it deposits suc- 
cessive crusts of a difficultly soluble green salt, probably a sub- 
sulphate of uranium, and the supernatant liquor becomes acid, 
but cannot be made to crystallize. 
Dilute sulphuric acid was digested upon moist oxide of ura- 
nium, untila perfectly neutral solution was obtained. A por- 
tion of this solution was decomposed by caustic ammonia, and 
the precipitated oxide, duly washed and ignited, weighed 62 
grains. The solution from which the above 62 grains of oxide 
had been thrown down was neutralized by nitric acid, and pre- 
cipitated by muriate of baryta. It yielded 85 grains of dry 
sulphate of baryta, which is equivalent to 22 grains of sulphuric 
acid; here, therefore, it would appear that dry sulphate of 
uranium consists of 62 oxide=68.1 
29 acid 31.9 
91 100. 
and, assuming 40 as the prime equivalent of sulphuric acid, 
that of oxide of uranium will be 85.6, and of the metal 77 6, a 
number not very different from that obtained by the analysis 
of the nitrate. 
V. When solution of nitrate of uranium is decomposed by car- 
bonate of ammonia, a very slight excess of the latter dissolves a 
considerable portion of the precipitate, and which, when col- 
lected and dried, appears to retain the carbonic acid very feebly, 
and not to be of uniform composition, but a mixture of oxide 
and carbonate. In several experiments, in which the supposed 
carbonate of uranium was decomposed by muriatic acid over 
mercury, the proportion of carbonic acid evolved was various. 
The following is the best experiment that was made with the 
precipitated carbonate : 30 grains were decomposed over mer- 
eury, by muriatic acid ; they evolyed 2.9 cubic inches of carbonic 
‘ 
