224 Peters — Estimation of Calcium, Strontium, etc. 





Table VIII. 





SrO, 



SrO, 



calculated 



taken as 



from SrCO; 



Sr(N0 3 ) 2 . 



found. 



grm. 



grm. 



1 0-1120 



0-1113 



2 0*1120 



0-1116 



3 0-2435 



0-2425 



SrO, 



calculated 



SrS0 4 



found. 



grm. 



0-2437 



Precipitates of barium oxalate were also ignited from 5-10 

 minutes and weighed as the carbonate. The results are given 

 in Table IX, and are fairly accurate. 





Table IX. 





BaO, 



BaO, 





taken as 



found as 





Ba(N0 3 ) 2 . 



BaC0 3 . 



Difference. 



grm. 



grm. 



grm. 



0-2912 



0-2909 



— 0-0003 



a 



0-2901 



—o-ooii 



u 



0-2901 



—o-ooii 



The results of this work may be summarized as follows : In 

 the estimation of calcium by titration of the oxalate with per- 

 manganate, accurate results may be obtained when hydro- 

 chloric acid (with a manganous salt) is used as the solvent. 

 Strontium salts may be precipitated by ammonium oxalate 

 with practical completeness in a solution containing one-fifth 

 its volume of 85 per cent alcohol, and with approximate com- 

 pleteness from water solutions at a dilution not exceeding 

 250 cm3 . Furthermore, strontium oxalate may be titrated by 

 permanganate with accuracy when either sulphuric acid or 

 hydrochloric acid (with a manganous salt) is used to liberate 

 the oxalic acid. Barium salts may be precipitated with prac- 

 tical completeness by ammonium oxalate in a solution contain- 

 ing one-third its volume of alcohol (85 per cent) and the barium 

 oxalate thus obtained may be dissolved in hydrochloric acid 

 and titrated by permanganate after the addition of a manga- 

 nous salt. Strontium and barium oxalates may be converted to 

 the carbonates by ignition and weighed as such. 



