Separation of Strontium from Calcium. 53 



sulphate and weighed as such, and the results of these experi- 

 ments (5 and 6) go to show that the composition of the stron- 

 tium nitrate is not appreciably changed in the process of 

 separation and drying. In certain other experiments directed 

 to the same end, the residues of the process of separation were, 

 after weighing and drying, treated with a drop of nitric acid, 

 and again dried at 150° C. and weighed. These tests (7) and 

 (8) confirm the indications of the previous experiments. Fi- 

 nally a third experiment was made upon strontium nitrate 

 dried at 150° C. to see what decomposition might result by 

 heating to temperatures somewhat higher than 150° C. — the 

 temperature at which the residues of the previous experiments 

 had been dried. The result shows that the loss in the twenty- 

 five degrees above 150° C. is exceedingly slight. 



( Sr(N0 3 ) 2 calculated as SrO 0-1219 grm. 



(5) } The same dissolved and precipitated as SrS0 4 



( calculated as SrO 0*1219 grm. 



J Sr(NO,) a calculated as SrO _• 0-1213 grm. 



(6) -j The same dissolved and precipitated as SrS0 4 



( calculated as SrO 0-1214 grm. 



f Sr(NO s ) a calculated as SrO 0-1228 grm. 



(7) -| The same dried at. 150° C. after adding a drop of 



( HN0 3 0-1228 grm. 



( Sr(N0 3 ) 2 calculated as SrO 0-1239 grm. 



(8) < The same dried at 150° C. after adding a drop of 



( HK0 3 0-1239 grm. 



( "Weight of Sr(N0 3 ) 2 dried at 150° C 0-2482 grm. 



(9) 1 Weight of the same portion dried at 165° C 0-2480 grm. 



( Weight of the same portion dried at 175° C. . . .0-2478 grm. 



When calcium nitrate was treated in a similar manner by 

 boiling with amyl alcohol the mass of the salt dissolved, but 

 minute portions separated out on the bottom or sides of the 

 beaker. Such residues were, however, very small and on 

 weighing were found not to exceed 0-0003 grm. or 0*0004 grm. 

 of the oxide. In several instances this insoluble residue was 

 washed thoroughly with ethyl alcohol, dissolved in water, 

 tested before the spectroscope and found to give the charac- 

 teristic calcium spectrum. All experience pointed to the fact 

 that the formations of the residue was due to some very slight 

 change of composition of the calcium nitrate. On one or two 

 occasions the acidified solution of the residue appeared to 

 reduce a drop of an extremely dilute solution of potassium 

 permanganate, and this action suggested the presence of a 

 nitrite. Treatment of this residue with nitric acid and subse- 

 quent evaporation of the excess of acid failed, however, to 

 leave the calcium salt in a condition to be dissolved by amyl 

 alcohol. 



