142 Hilleorand and Ransome — Carnolite and Associated 



Average quality of marketed ore. — As these carnotite ore 

 bodies are being exploited for the market, it is of some interest 

 to know the average quality of each commercial lot. A care- 

 fully prepared sample representing several tons of ore was 

 received from one of the commercial houses of Denver and was 

 found to carry 11'49 per cent of uranium counted as U 3 O g , and 

 6*40 per cent of vanadium counted as V 2 B . Over one-sixth 

 of the vanadium existed, however, in the trivalent state, not as 

 a constituent of the yellow body, but doubtless of a silicate like 

 the one whose composition is given on p. 143. 



Commercial assay. — The commercial assay of these ores has 

 presented difficulties to the technical chemist, the results being 

 sometimes very discordant. 



As to uranium this is not surprising. The methods that have 

 probably been commonly employed will give varying results 

 according to the contents of the ore in phosphorus and alkaline 

 earths. Possibly the old Patera process, described in most 

 text-books on analytical chemistry, might be made to serve, 

 with modifications called for by the large amount of vanadium 

 present. 



The assay for vanadium presents little difficulty and does 

 not require much time. The ore is fused with sodium carbo- 

 nate, leached with water and the fusion repeated on the residue. 

 The combined filtrates are acidified by sulphuric acid, arsenic 

 and molybdenum are precipitated in the hot solution by hydro- 

 gen sulphide, whereby the V 2 6 is reduced to Y 2 4 . After 

 filtration and expulsion of hydrogen sulphide by boiling, the 

 vanadium is titrated in hot solution by permanganate. It is 

 then reduced by sulphur dioxide gas, and after boiling this out 

 the titration is repeated. The results are exact, and they are 

 not affected by the uranium that may be present. 



IV. Composition of the Vanadiferous Silicate in the Carnotite 



Ore. 



As already mentioned the ores contain a vanadiferous silicate 

 free from uranium. To the end of ascertaining its composition 

 if possible, ore ~No. Ill (p. 128), from the Yellow Bird claim, 

 low in carnotite but relatively rich in vanadium, was treated 

 as follows : 



The carnotite from 10 grams was extracted by cold, dilute 

 nitric acid, and the well washed residue, consisting of coarse 

 sand and an utterly amorphous mud, by 4 per cent sodium 

 carbonate solution to get rid of the small amount of silica pre- 

 sumably set free but not dissolved by the acid. This amounted 

 to 0*35 per cent in duplicate determinations, and together with 

 0*06 per cent in the acid solution or 041 per cent in all, may 



