Uranyl Phosphate hy the Zinc Eeductor, 



233 



ammonmm phospho-moljbdate, Blair states that the solution 

 should alwajs be kept above the level of the zinc, so that no 

 air will pass into the reductor. This precaution was carefully 

 observed, for, by the action of nascent hydrogen, hydrogen 

 peroxide might be formed, and this would cause high results 

 in the process. 



The contents of the receiving flask after the operation were 

 of an olive-green color, but upon exposure to the air by pour- 

 ing into a porcelain dish the color changed immediately to the 

 sea-green color always possessed by uranous salts, and this 

 change of color is of itself evidence of oxidation. In the 

 titration of the hot solution of uranous sulphate with perman- 

 ganate the solution gradually became more and more of a 

 yellowish green color as it approached the highest condition of 

 oxidation. With small amounts of uranium the addition of a 

 single drop of permanganate in excess caused the whole solu- 

 tion to change to a very faint pink color, but with larger 

 amounts the solution became a yellowish pink upon adding the 

 excess of permanganate, and the end-point was harder to read. 



The results obtained are shown in the table : 



Uranyl 

 sulphate 

 taken, in 

 terms of 



UO3. 



grm. 



H2SO4 



(1-84). 

 cm^. 



Dilution 

 at time 

 of reduc- 

 tion, 

 cm^. 



Time, 

 minutes. 



KMn04. 

 om^. grm. UO3. 



Error in 

 terms 



of UO3. 

 grm. 



0-1336 



18 



117 



15 



9-32 



0-1334 



-0-0002 



0-1337 



20 



120 



15 



9-37 



0-1341 



-f 0-0004 



0-1336 



25 



125 



17 



9-40 



0-1345 



-^ 0-0009 



0-2005 



18 



117 



20 



14-02 



0-2006 



-1-0-0001 



0-2003 



25 



125 



17 



14-01 



0-2005 



-f 0-0002 



0-26n 



23 



150 



20 



18-67 



0-2671 



±0-0000 



0-26'73 



20 



140 



18 



18-05 



0-2669 



— 0-0004 



0-1001 



25 



125 



22 



706 



0-1010 



-h 0-0009 



0-1002 



20 



140 



17 



7-02 



0-1004 



4-0-0002 



0-1002 



20 



140 



14 



7-01 



0-1003 



-f-0-0001 



0-0668 



18 



117 



17 



4-70 



0-0673 



+ 0-0005 



0-0994 



20 



100 



16 



6-96 



0-0995 



-fO-0001 



0-1988 



20 



120 



18 



13-90 



0-1988 



±0-0000 



0-1988 



25 



150 



18 



13-88 



0-1985 



-0-0003 



0-3314 



25 



150 



27 



23-14 



0-3309 



— 0-0005 



0-3314 



30 



150 



36 



23-19 



0-3316 



+ 0-0002 



0-3314 



25 



145 



33 



23-17 



0-3313 



—0-0001 



Since the uranium, by contact with the air, is oxidized 

 exactly to the stage of oxidation represented by UOj, and since 

 in a few preliminary experiments carried out in the presence of 

 carbon dioxide it apparently remained reduced below that 

 stage, it appeared that it might be interesting to investigate 



