Barium, as the Oxalates. 217 



« 





Table I. 







CaO, 





Volume 







taken as 



Ammonium 



at 



CaO 





CaCl 2 . 



oxalate. 



precipitation. 



found. 



Error. 



grm. 



grm. 



cm 3 . 



grm. 



grm. 



0-0656 



0-3 



100 



0-0657 



+ 0-0001 



a 



tt 



100 



0-0656 



o-oooo 



u 



a 



150 



0-0658 



+ 0-0002 



a 



a 



100 



0-0655 



—o-oooi 



0*0985 



0-5 



175 



0-0981 



— 00004 



0-1313 



0-6 



150 



0-1315 



+ 0-0002 



a 



a 



200 



0-1315 



+ 0-0002 



In one experiment, for example, in which the precipitate, on 

 the felt, was washed fourteen times with portions of about 

 50 cm3 each of hot water, each portion bleached from 2-6 drops 

 of approximately one-tenth normal permanganate, making a 

 total loss of 0*0034 grm. of calcium oxide. 



/Strontium Oxalate. 



Souchay and Lenssen* state that strontium oxalate is soluble 

 in 12,000 parts of water. This fact seemed sufficient to war- 

 rant the study of the quantitative separation of strontium as 

 the oxalate. In the work which follows strontium oxalate has 

 been precipitated both in alcoholic solution and in water solu- 

 tion, and for convenience these two conditions of precipitation 

 will be discussed separately. All the strontium salts, of estab- 

 lished purity, were standardized by precipitation with sul- 

 phuric acid in a solution containing at least one-half its volume 

 of alcohol, and with some solutions confirmatory standards 

 were also obtained by e vaporization with sulphuric acid. 



Precipitation in Alcoholic Solution. — To determine the 

 completeness of the precipitation in alcoholic solution stron- 

 tium nitrate was precipitated by ammonium oxalate in a solu- 

 tion containing one-third of its volume of alcohol, the mixture 

 was allowed to stand over night, the liquid was filtered off on 

 asbestos, and the precipitate was treated in the capped filtering 

 crucible with sulphuric acid, ignited, and weighed as the 

 sulphate. 



The results are given in Table II. 



It is plain from the results recorded in this table that the 

 precipitation of even small amounts of the strontium salt from 

 a solution containing one-third of its volume of alcohol is prac- 

 tically complete. 



To determine the minimum amount of alcohol necessary for 

 the complete precipitation of the strontium oxalate, experi- 



* Ann. der Chem. (Liebig), cii, 35. 



