84 Browning and Palmer — Estimation of Cerium. 



ganate used in the actual determination. It is of interest to- 

 note that ferricyanide solutions kept in clear glass bottles for 

 a week or more showed variations of only a drop or two in the 

 amount of permanganate taken up. 



All the various operations in this process were carried on 

 without warming the solution. The titrations and washings 

 were generally made under gentle pressure, and required on 

 an average not more than fifteen to thirty minutes. In Table 

 I the results obtained with cerium present alone are given. 



Table I. 

 Ce taken, calcu- Ce found, calcu- 

 lated as Ce 2 8 lated as Ce 2 3 Error 

 grm. grin, grm. 



0*1819 —0-0015 



0-1380 +0-0004 



0*1829 —0-0005 



0-1829 —0-0005 



0-1834 +0-0000 



0-1385 +0-0009 



0-1371 —0-0005 



0-1374 —0-0002 



0-1380 +0-0004 



0-1824 —0-0010 



0-1335 +0-0009 



0-1328 +0-0002 



f the other rare earths, containing 

 were treated by the same method, and the 

 failure to obtain evidence, by the permanganate, of the for- 

 mation of potassium ferrocyanide, showed that there is no 

 oxidation of these salts by the ferricyanide. 



In Table II the results obtained by estimating cerium 

 according to this method in the presence of the other rare 

 earths are given. 



Table II. 



(1) 



0-1834 



(2) 



0-1376 



(•') 



0-1834 



w 



0-1834 



(5) 



0-1834 



(6) 



0-1376 



(?) 



0-1376 



(8) 



0-1376 



(9) 



0*1376 



(10) 



01834 



(U) 



0-1326 



(12) 



0-1326 



Solutions of the salt 



about 0*1 grm. 



, were 



Ce taken, calcu- 



Ce found, 



calcu- Other Rare Earths present 



] 



ated as Ce 2 3 



lated as 



C!e 2 



j Error 



calculated as oxides 





grm. 



grm. 





grm. 



grm. 



(1) 



0-1328 



0-1335 





+ 0-0007 



0-lThO 2 



(2) 



0-1327 



0-1322 





— 0-0005 



0-1 " 



(3) 



0-0266 



0-0275 





+ 0-0009 



0-1 " 



(4) 



0-0267 



0-0272 





+ 0-0005 



o-i " 



(5) 



0-1324 



01326 





+ 0-0002 



o-iY 2 3 



(6) 



0-1326 



0*1323 





-0-0003 



o-i " 



(?) 



0-0266 



0-0264 





— 0-0002 



o-i " 



(8) 



0-0264 



0-0271 





+ 0-0005 



o-i " 



(9) 



0-1376 



0-1370 





— 0-0006 



0-15La 2 O 3 + Di 2 O, 



(10) 



0-1101 



0-1091 





-o-ooio 



0-15 " " 



(11) 



0-1324 



0-1332 





+ 0-0008 



0'03ZrO 2 



This method presents no difficulties in manipulation and is 

 especially adapted to the rapid estimation of cerium in rare 

 earth mixtures. 



