FOR SEPARATING THE ALKALINE EARTHS. VICKERY. 37 



as chloride, failrd to form a precipitate in lo niinutcs, or 

 to leave a deposit on the filter. Hence tlio limit of detection 

 of barium using the ordinary procedure is 4 mg. when excess 

 of the others is present. 



A solution containing 15 mg. of strontium and 200 mg. 

 each of calcium and l)arium was treated b}- the ordinary' 

 procedure and the barium removed. Insufficient ammonium 

 chloride was added and a considerable precipitate formed 

 with the ammonium sulphate. This was boiled with am- 

 monium carbonate and dissolved in acetic acid and calcium 

 sulphate added. A very fine precipitate formed in the 

 course of a few hours. A similar solution was taken and 

 sufficient ammonium chloride (i.e. 80cc) was added, after 

 removing the barium, to hold up the calcium. A very fine 

 granular precipitate was obtained with ammonium sulphate 

 in a few minutes, and no trace of the typical calcium crystals. 

 Its identity was easily established. A solution with 1.3 mg. 

 of strontium failed to give a precipitate, hence the limit 

 of deteetability of strontium is 1.5 mg. when an excess of 

 barium and calcium is present. 



A solution containing 1 mg. of calcium, 200 mg. of barium 

 and 500 mg. of strontium was treated as before, and the 

 barium and strontium removed as chromate and sulphate 

 respectively. A fine white precipitate appeared in a few 

 moments on making alkaline and adding ammonium oxalate, 

 A solution containing 0.5 mg. gave no precipitate on boiling 

 15 minutes, but gave a very fine deposit on standing over 

 night. Hence, the limit of deteetability of calcium is 1 mg. 

 or somewhat under, when excess of barium and strontium are 

 present. 



PROPOSED PROCEDURE 



The results of the investigation can best be summarized 

 by giving a procedure with notes for the separation of the 

 alkaline earths by the improved chromate process. 



