SEPARATION OF THE METALS NICKERSON 27 



concentrations. The ordinary C. P. chemicals were used in 

 all cases. 



Acetic Acid 3 N. solution 



Ammonium Hydroxide 3 N. solution. 



Ammonium Carbonate 3 N. solution. 



Ammonium Sulphate 10% solution. 



Ammonium Oxalate Saturated solution at 15° C. 



Potassium Chromate 10% solution. 



Test solutions of the chlorides of barium, strontium and calcium 

 were prepared of such concentration that 1 cc of solution con- 

 tained 5 mgs. of the metal. 



Separation of Ba and Sr. 



The method given in the procedure above for the separa- 

 tion of these ions involves nothing new. It was necessary 

 however to study the separation quantitatively to determine 

 its practical limits of accuracy so far as this particular proce- 

 dure was concerned. Assuming that the detection of about 2 

 mgs. of barium in 100 cc's of solution represents reasonable 

 accuracy in a separation of this kind, it was only necessary to 

 determine the amount of acetic acid which would allow the 

 precipitation of that quantity of barium as barium chromate, 

 and also to determine the maximum amount of strontium 

 chromate which could be held in solution by the same concen- 

 tration of acetic acid. 



Separation of Barium and Strontium. 



Separations of barium and strontium were carried out 

 according to the method given, using varying concentrations 

 of acetic acid. The solubility of the barium chromate was 

 found to increase rapidly as the excess of acetic acid was in- 

 creased. With an excess of 3 cc's of 3 N. acetic acid, it was 

 found that 1.5 mgs. of barium gave a noticeable precipitate of 

 barium chromate, while under similar conditions, as much as 

 500 mgs. of strontium gave no trace of precipitate. 



