60 Mr. R. Phillips's Analysis of Uranite. [Jan. 



the 100 grains submitted to analysis. Suspecting, therefore, 

 that some phosphoric acid had been volatilized with the water, 

 I held litmus paper over a further portion of the mineral while 

 subjected to the heat of the lamp ; I found that it was reddened 

 during the expulsion of the last portions of the water, and tur- 

 meric paper, which had been reddened by ammonia, had its 

 yellow colour restored by the phosphoric acid thus volatilized. 



M. Berzelius, it has been already stated, attributes the green 

 colour of this mineral to the presence of arseniate of coppei\ In 

 order to examine this point, Mr. Children was good enough to 

 submit some crystals to the blowpipe while I was present. 

 When crystals without admixture were heated upon charcoal, 

 not the slightest arsenical smell could be perceived by either 

 of us ; but when the ore was pulverised and mixed with bicar- 

 bonate of soda, and strongly heated in the reducing flame on 

 charcoal, a slightly arsenical smell was discoverable, but no 

 fumes were visible. As, however, this ore contains so large a 

 portion as nine per cent, of oxide of copper, the arsenic acid, 

 combined with it, would be detected with the greatest facility. 



Still further to examine whether the oxide of copper is in 

 combination with arsenic acid, I supersaturated some of a 

 nitric solution of the mineral with ammonia. By this the arse- 

 niate of copper would be dissolved, and the phosphate of ura- 

 nium precipitated without decomposition. I boiled some of 

 the ammoniacal solution with potash, and added nitrate of 

 silver to the filtered solution ; a yellow precipitate was obtained 

 having a scarcely perceptible tinge of red, instead of being of a 

 deep-red colour, as would have occurred if arsenic acid had 

 been present in sufficient quantity to form arseniate with the 

 oxide of copper. It is, therefore, evident, that the oxide of copper 

 is in the state of phosphate, a circumstance which is likely to 

 occur, when it is known that the mine which produces the ura- 

 nite also yields phosphate of copper. 



It is difficult to determine in what state of oxidation the 

 uranium exists in the mineral ; but as it is acted upon during 

 analysis by nitric acid, and as I found by direct experiment that 

 when dissolved in nitric acid, and heated to redness, it gained 

 no weight, I think we may conclude, that it is procured in the 

 state of peroxide, and I shall consider it as existing in this 

 state in the ore. 



According to Dr. Thomson, hydrogen = 1 ; the atom of 

 peroxide of uranium is represented by 137, and that of phosphoric 

 acid by 28 ; 60 will, therefore, combine with 12-2 of phosphoric 

 acid, forming 72-2 of phosphate of uranium, and there remain 

 3-8 of phosphoric acid to combine with 9 of peroxide of copper; 

 but as phosphate of copper is composed of 80 oxide and 28 acid, 

 or 1 atom of each, 9 of oxide will combine with only3T of acid, 

 leaving an excess of 0*7. 



Supposing the phosphate of uranium to be combined with 

 three atoms of water, and the phosphate of copper, as deter- 



