270 Browning and Jones — Estimation of Cadmium. 



presence of a few drops of sulphuric acid, igniting at low red- 

 ness, and weighing as the anhydrous sulphate. The average of 

 several closely agreeing results was taken as the standard. 

 Measured and weighed portions of this solution were diluted 

 to about 300 cm^ with hot water and a solution of potassium car- 

 bonate, 10 per cent, added drop by drop with constant stirring 

 until no further precipitate was obtained. The precipitate was 

 then boiled for about fifteen minutes, when it became granular 

 and settled quickly. It was then filtered upon asbestos, washed 

 thoroughly, dried, and ignited at red heat until a constant 

 weight was obtained. In several instances the weighed oxide 

 was treated with a drop of nitric acid, again ignited and 

 weighed, but in no case was there a perceptible change in 

 weight. In the following table the results are tabulated. 



CdO found. Error, 



grm, grm. 



0-1143 0-0003 + 



0-113'7 0-0005 — 



0-1148 00007 + 



0-1148 0-0007 + 



0-1146 0-0004 + 



0-1147 0-0004 + 



0-1144 0-0001 + 



0-1146 0-0007 + 



0-1272 0-0002 + 



0-1283 0-0004 + 



0-1281 0-0009 + 



0-1281 0-0003 + 



0-2561 0-0005 + 



0-2547 0-0003— • 



0-1279 0-0007 + 



0-1288 0-0007 + 



0-1278 0-0004 + 



0-1290 0-0006 + 



0-1277 0-0006 + 



0-1285 0-0007 + 



0-2555 0-0000 + 



As will be noticed, the results show a plus error which might 

 naturally be due to a slight inclusion of the alkali carbonate. 

 To test the truth of this hypothesis, a portion of the oxide 

 which gave a plus error of 0-0007 grm. was dissolved and 

 tested for potassium by the perchloric acid method* and an 

 amount of that element was found equal to 0*0006 grm. of the 

 carbonate. Another portion of the oxide which showed no 

 error was similarly treated and only 0*0002 grm. on the car- 

 bonate was found. The results show, as we think, that the 

 carbonate method can be successfully applied to the quantita- 

 tive estimation of cadmium without recourse to the tedious 

 process of manipulation recommended by Muspratt. 



June, 1896. 



* Kreider, this Journal, vol. xlix, 443. 



No. 



CdO taken 





grm. 



(1) 







1140 



(2) 







1142 



{^) 







1141 



(4) 







1141 



(5) 







1142 



(6) 







1143 



(7) 







1143 



(8) 







1139 



(9) 







1270 



(10) 







1279 



(11) 







1272 



(12) 







1278 



(13) 







2556 



(14) 







2550 



(15) 







1272 



(16) 







1281 



(IV) 







1274 



(18) 



0- 



1284 



(19) 







1271 



(20) 







1278 



(21) 







2555 



