Browning — Separation and Detection of Strontium. 387 



to keep the inflammable fumes of the alcohol from the flame. 

 Five cubic centimeters of the alcohol is a convenient amount 

 to use in each boiling and the error introduced by the solubil- 

 ity of the strontium salt is thus reduced to a minimum, the 

 solubility in 30cm 3 having been determined to be 0*001 grm. of 

 the oxide. Experiments made to test the delicacy of the 

 method as regards the detection of strontium alone are re- 

 corded in Series I (5), (6), (7), (8), (9) ; and (10), (11), (12), (13), 

 give the results of the treatment in the presence of both 

 strontium and calcium. Into a test tube is put the mixture of 

 the nitrates of strontium and calcium not exceeding - 2 grm., 

 that being the limit of the solubility of calcium nitrate in 

 5cm 3 of amyl alcohol. After dissolving in a few drops of 

 water 5cm 3 of amyl alcohol are added and the boiling is carried 

 on until the normal boiling point of the alcohol, 128-130° C, 

 is reached. If strontium is present to the amount of 0-001 

 grm. of the oxide or more a very decided separation takes 

 place. If the amount is smaller it cannot be readily distin- 

 guished from the residual spots deposited on the bottom of the 

 tube by the calcium salt. The alcohol containing the calcium 

 salt dissolved is decanted upon a dry filter paper in a dry 

 funnel and the residue washed in the tube with about 5cm 3 of 

 absolute ethyl alcohol, this also being filtered into the tube 

 containing the amyl alcohol. The filtrate is reserved to be 

 tested for calcium, while the residue, if so small that it may 

 be a calcium deposit, is dried gently and finally ignited by 

 agitating the tube over a flame. After cooling the tube a few 

 drops of water and a drop of nitric acid are added and the 

 boiling repeated. As the results of Series I show, any amount 

 of strontium above - 0005 grm. of the oxide separates out dis- 

 tinctly, while the slight calcium residue does not reappear. 

 My experience has been that amounts of calcium nitrate equal 

 to 0*2 grm. give a deposit on the first boiling about equal to 

 0*0003 grm. of strontium oxide on the first boiling. The 

 residues from the second treatment in Series I (5) to (13) were 

 all dissolved in a few drops of water treated with a drop of 

 hydrochloric acid and tested before the spectroscope, all giving 

 distinct strontium lines but no trace of calcium. The calcium 

 residues from the first boiling gave distinct calcium lines but 

 no trace of strontium. 



The delicacy of the process in the detection of calcium is 

 shown by the experiments of Series II. The method of treat- 

 ment was the same as described above excepting that the fil- 

 trates and washings after the first boiling were used for these 

 tests. To these clear filtrates about 2cm 3 of dilute sulphuric 

 acid were added, and in five minutes or less the results recorded 

 were apparent. When strontium alone was taken either in 



