Uranyl Phosphate hy the Zinc Reductor 



235 



The following results were obtained 



Uranyl 

 sulphate 



taken, 



in terms 



of UO3. 



grm. 



H2SO4 



(1-84). 

 cm^. 



Dilution 

 at time 

 of reduc- 

 tion, 

 cm^. 



Time, 

 minutes. 



KMnOi used 

 after deduct- 

 ing cm^. of 

 oxalate, 

 cm^. grm. UO3. 



Amount 

 of UO3 



more 



than 

 theory. 



grm. 



0-1336 



20 



120 



13 



10-41 



0-1490 



-f o-oi.U 



0-1337 



20 



120 



17 



10-54 



0-1508 



+ 0-0171 



0-2004 



20 



120 



15 



15-71 



0-2247 



+ 0-0243 



0-2003 



25 



125 



19 



15-68 



0-2242 



+ 0-0239 



0-1002 



20 



120 



18 



7-56 



0-1081 



+ 0-0079 



0-0668 



18 



90 



18 



5-12 



0-0732 



+ 0-0064 



0-2658 



25 



125 



16 



20-60 



0-2946 



+ 0-0288 



0-2672 



20 



120 



15 



21-11 



0-3019 



+ 0-0347 



0-1002 



18 



90 



15 



8-01 



0-1145 



+ 0-0143 



In order to be certain that the cause for this apparent over- 

 reduction was not partially due to the setting free of oxygen 

 during the interaction of the permanganate and the oxalic acid 

 in the strongly acid solution of sulphuric acid, it was decided 

 to investigate the point. In an article from this laboratory,* 

 it is shown that in the presence of 20 per cent of sulphuric 

 acid (1 : 1) there is no a-ppreciable loss of the permanganate at 

 the ordinary temperature under an exposure of a few hours 

 only. The results, however, were obtained with small volumes 

 and at the ordinary room temperature, while in the uranium 

 process there was a much larger volume at a temperature of 

 from 30° to 40° when the permanganate and oxalic acid were 

 added. Some blanks, therefore, were carried out as follows : 

 Approximately 550^"^^ of distilled water were placed in a flask, 

 25cm3 ^1 strong sulphuric acid added, the mixture heated to 



about 40°, and 19^™^ of a — solution of permanganate run 



in. A slight excess of a — ammonium oxalate solution was 



^ 10 



then added, the mixture warmed to about 60°, and the final 

 end-point taken with permanganate. It was found that there 

 was no loss of the permanganate, the same results being given 

 in this way as when the ammonium oxalate was diluted to 

 gQQcms ^^(j \iiQY adding 25'°"' of sulphuric acid was heated to 

 60° and titrated directly with permanganate. 



Since there was no loss between the permanganate and the 

 oxalic acid (and there is no other apparent cause for error), the 



*Danner and Gooch, this Journal, vol. xliv (1892), 304. 



Am. Jour. Sci. — Fourth Series, Yol. XVI, No. 93. — September, 1903. 

 16 



