Vanadiferous Minerals in Western Colorado. 143 



serve as a maximum figure by which to gauge the action of the 

 cold acid on the silicate or silicates in the ore. The residue 

 was then digested for several hours with warm nitric acid of 

 about 1*2 sp. gr. until as shown by a companion test its action 

 had ceased. It was then filtered, washed and digested with 5 

 per cent sodium carbonate solution to dissolve the copious 

 deposit of silica. The final residue was collected in a Gooch 

 crucible, washed with sodium carbonate, followed by dilute 

 nitric acid to remove all alkali, then by alcohol to prevent tur- 

 bidity in the filtrate, and dried by suction of the pump. In it 

 the water was determined at different temperatures, also its 

 general composition.- From the sodium carbonate filtrate the 

 silica was obtained by two evaporations and filtrations, also the 

 trifling amount held by the acid solution. This latter was then 

 fully analyzed and the complete results follow. 



Composition of vanadiferous silicate in carnotite ore. 



Per cent 

 Per cent calculated 



in ore. to 100. Eatios. 



SiO„ 6-48 43-94 '7275 



A1„0 3 2-445 (2-45 and 2-44) ■ 16*58 '1622) 



V a "O s -965 ( -93 and 1-00) 6-54 -0434 [■ -2426 



Fe 2 3 -875 ( -87 and -88) 5-93 -0370) 



CaO __ -035 -24 -0043) ,,,„ 



MgO._ -654 ( -652 and -657) 4-43 -1099 f 



K„0 -546 3-70 -0393 A , on 



Na o -03 -20 •0037[ 0430 



H o 105° C. l'66f 11-26 -9222 



H 2 O300°C -44f 2-98 '1655 



H 2 above 300° C. -62f 4-20 -2333 



14-75 100-00 



Also traces of titanium, manganese, and lithium. 



On the improbable assumption that the iron is to be wholly 

 included, and regarding only the water given off above 300°, 

 the following ratios result : 



H 467 R '86 R "n4 R,,/ 485 Si , 2 , 2 673 5 



which become, if the iron is excluded, 



H 467 R'se R ''n4 R '"4U Si 72 7 2 46 2 " 



These figures, while strongly suggesting definite ratios 

 between certain of the constituents, do not under the circum- 

 stances warrant the deduction of a formula, nor do they lead 



*Si0 2 48-89, A1 2 3 , Fe 2 3 , zircon etc., -44, Ti0 2 -08, MgO -01, K*0 -11, Na»0 

 ■03, H 2 -07 ; total 4963. 



f Determined on a separate portion of the same powdered sample. See p. 138 

 footnote for data. 



