aiLLEBRAND.] CARNOTITE AND ASSOCIATED MINERALS. 29 
barium. This is very remarkable in view of the fact that all the ores 
Prom different localities, examined by me show large admixture of 
calcium or barium salts or both, even that which is certified to have 
jome from the same lot as that from which their material was taken, 
rhe French authors give a brief outline of their methods of analysis, 
rttat one which afforded them the best results would involve the 
weighing of any calcium present as sulphate along with the potassium, 
3n the assumption that the presence of that element had been over- 
looked. It is much to be desired that a reanalysis of their material 
should be made, if there is any of it still available, in order to clear 
up the doubt connected with the first analysis. 
In the light of the evidence herein set forth, the existence of a dis- 
tinct mineral species having the composition claimed for carnotite can 
by no means be considered as established. 
AVERAGE QUALITY OF MARKETED ORE. 
As these carnotite ore bodies are being exploited for the market, it 
s of some interest to know the average quality of each commercial 
ot. A carefully prepared sample representing several tons of ore was 
•eceived from one of the commercial houses of Denver and was found 
o carry 11.49 per cent of uranium counted as U 3 8 , and 6.40 per cent 
>f vanadium counted as V 2 5 . Over one-sixth of the vanadium existed, 
lowever, in the trivalent state, not as a constituent of the yellow body, 
>ut doubtless of a silicate like the one whose composition is given on 
>age 30. 
COMMERCIAL ASSAY. 
The commercial assay of these ores has presented difficulties to the 
echnical chemist, the results being sometimes very discordant. 
As to uranium, this is not surprising. The methods that have prob- 
bly been commonly employed will give varying results, according to 
le contents of the ore in phosphorus and alkaline earths. Possibly 
le old Patera process, described in most text-books on analytical 
hemistry, might be made to serve, with modifications called for by 
le large amount of vanadium present. 
The assay for vanadium presents little difficulty and does not require 
mch time. The ore is fused with sodium carbonate, leached with 
ater, and the fusion repeated on the residue. The combined filtrates 
re acidified by sulphuric acid, arsenic and molybdenum are precipi- 
^ted in the hot solution by hydrogen sulphide, whereby the V 2 6 is 
iduced to V 2 4 . After filtration and expulsion of hydrogen sulphide 
y boiling, the vanadium is titrated in hot solution by permanganate. 
; is then reduced by sulphur dioxide gas, and after boiling this out 
le titration is repeated. The results are exact, and they are not 
lected by the uranium that may be present. 
