AET. 12 CAENOTITE FROM UTAH HESS AND FOSHAG t> 



acid (H20 = 1.32 per cent) showed, with sulphur-selenium melts, the 

 following indices of refraction: /3=2.06 and y=2.08 for Na light. 

 The mineral left over sulphuric acid of a water vapor pressure of 19 

 mm. (H20=1.T2 per cent) was somewhat lower, /?=2.04, y=2.06. 



CHEMICAL PROPERTIES 

 Oontriduted iy William F. Foshag 



For analysis there were selected the thicker crusts that were easily 

 detached from the rock. These had a maximum thickness of 2 mm. 

 and were entirely made up of coarse, clean plates. The lower sur- 

 face of the crusts was pared with a knife to remove any adhering sand 

 grains or calcite from the sandstone cement. The mineral was then 

 crushed to pass 100 mesh and the material thus prepared was ex- 

 amined under the petrographic microscope for impurities. The 

 sample consisted almost wholly of clear, coarse, transparent plates of 

 carnotite of a bright yellow color. Some of the larger grains had 

 a clouded appearance but reflected light showed this effect to be due 

 to included air spaces. A careful search revealed no visible grains 

 of calcite. 



The analysis of the carnotite was accomplished as follows : Water 

 was determined both directly and as loss on ignition. As these two 

 determinations gave essentially the same amounts of water later 

 determinations were made wholly as ignition loss. The vanadium 

 was separated from the other constituents by volatilization as vana- 

 dium chloride in a stream of dry hydrochloric acid gas. The 

 distillate was examined for molybdenum, phosphorus, iron, arsenic, 

 and lead and found to be essentially free of these elements. The 

 vanadium was then reduced with sulphur dioxide and titrated with 

 potassium permanganate solution after removal of the SOo by boil- 

 ing in a stream of carbon dioxide. The residue in the boat, left from 

 the distillation of the vanadium was entirely soluble in water except 

 for a small amount of gangue. Hydrogen sulphide passed into this 

 acidified solution gave only traces of lead and copper. The uranium, 

 iron, and alumina after oxidation of the iron were separated from the 

 lime and magnesia by three precipitations with carbonate free 

 ammonia. The separations of these constituents were made by the 

 usual methods. Alkalis were determined in a separate portion after 

 the vanadium was separated by distillation, uranium, iron, and 

 alumina by freshly prepared ammonium sulphide and lime and 

 magnesia by ammonium carbonate and ammonium oxalate. The 

 results of the analysis together with the calculated ratios and the 

 theoretical composition for the compound KjO. 2UO3. V2O5. 2/3H2O. 

 is given in the table below. , 



