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 XXXVII. Intelligence and Miscellaneous Articles. 



ON THE COMPOSITION OF THE PHOSPHATES OF URANIUM. 

 BY M. WERTHEIl. 



THE author obtained two phosphates of uranium in a state of 

 purity. When oxide of uranium is diffused in a small quan- 

 tity of phosphoric acid, a saline mass of a bright yellow is formed, 

 part of which is dissolved by ebullition, and part remains insoluble. 

 The yellow solution, when sufficiently concentrated, deposits after 

 long exposure over sulphuric acid, a lemon-coloured salt in irregular 

 crystals, collected in groups. These crystals gave the following 

 results by analysis : — at 212° F. they lost 7*5 per cent.; at 248°, 

 10'2 per cent. ; after long exposure to 320°, they lost 13*11 ; and 

 by calcination 17*9 per cent, of water. Another portion lost by 

 calcination 16*8 per cent, of water, gave 26*7 of phosphoric acid,, 

 and 55'96 of oxide of uranium ; a third portion lost 12' 1 per cent, 

 of water at 230°, 17"2 by calcination, and gave 54*6 per cent, of oxide 

 of uranium ; lastly, a fourth portion gave 27'49 of phosphoric acid. 

 The mode of estimating adopted by the author was the following: — 

 He fused some potassio-tartrate of soda in a platina crucible, and 

 carbonized it with a sufficient degree of heat, out of contact of the 

 air, and added to it a noted weight of phosphate of uranium. The 

 heat must not be continued longer than is requisite to fuse the black 

 mass : by this all the sesquioxide is reduced to protoxide, and from 

 it water will dissolve all the phosphate of soda, and the excess of 

 carbonate, unmixed with even a trace of uranium, the protoxide of 

 which remains on the filter, mixed with charcoal. 



M. Werther recommends two precautions in this operation to avoid 

 decomposing the phosphoric acid, and consequently to prevent the 

 perforation of the crucible : the phosphate of uranium must not be 

 placed at the bottom of the crucible, and then merely introduce the 

 potassio-tartrate of soda ; again, the heat must not be raised above 

 the degree -of redness requisite to effect the decomposition. 



Sometimes small flames appear during the fusion ; they are occa- 

 sioned merely by oxide of carbon. The filtered portion containing 

 the phosphoric acid is saturated by hydrochloric acid, mixed with 

 excess of ammonia and precipitated by sulphate of magnesia. As to 

 the protoxide remaining on the filter, it is to be dissolved in nitric 

 acid, precipitated by ammonia, and the precipitate is to be calcined. 

 The preceding results lead to the formula [P 2 O 5 , U 2 O 3 + 5H 2 0] ; 

 or reckoning 2H 2 as constituting an integrant part of the salt 

 [P 2 s , U 2 2 0, 2H 2 + 3 aq] . It is, however, correct to state that 

 all the water is expelled between 338° and 356° F. 



This phosphate of uranium is decomposed by water into phos- 

 phoric acid, holding a little oxide of uranium in solution, and an 

 insoluble subphosphate of uranium. If the latter be dissolved in 

 phosphoric acid and precipitated by ammonia, a yellow salt is depo- 

 sited which retains ammonia after repeated washings. 



The phosphate of uranium, corresponding to common phosphate 



