of some American Minerals. 39 
its carbonic acid at a temperature below that required to drive 
off all the water, nor is it rendered less soluble by exposure 
to the strongest heat of a Berzelius. lamp. 
No traces of sulphur could be found by boiling the mineral 
with fuming nitric acid, and testing with chloride of barium. 
The lead has therefore been calculated as oxide, and not as a 
sulphuret. 
The per centage results of two analyses are as follows: 
he II. 
EM 4 oo oe 4805 5.60 
Alumina. : : ; .90 
Oxide of iron ; ; » eee iiie 
Oxide of uranium i . 59,90 51.54 
Oxide of lead : A . 5.36 5.84 
Lime : . ‘ . 14.44 13.47 
Carbonic acid i . "erm ri 
. Water " : 4.64 
Magnesia and idioma traces 
98.70 
That the uranium exists in the mineral as E, and not as 
U €, as in the common pitchblende, is evident from its ready 
solubility in acids; and that the oxide of uranium, or uranic 
acid as it might with equal propriety be called, is in chem- 
ical combination in the mineral is equally evident, from the 
fact that its solubility is not diminished by ignition. That the 
silica is also chemically combined is shown by the fact that it 
is separated in a state in which it is soluble in carbonate of 
soda. It is difficult to see in exactly what manner these 
elements are combined with regard to each other, though it is 
probable that the oxide of uranium plays the part of an acid 
toward a portion of the lime, (the remaining portion being in 
combination with the carbonic acid) and the lead. The fre- 
quent occurrence of a small quantity of oxide of lead with 
the ores of uranium, is an interesting fact, on which future 
investigations may perhaps throw some light. 
