316 Browning — Separation of Barium from Calcium. 



The next experiments were directed toward a separation of 

 barium and calcium nitrates. Definite amounts of a solution 

 of barium nitrate were measured from burettes into counter- 

 poised beakers and weighed, as already described, the calcium 

 nitrate was then added in solution and the weight taken again. 

 The water was evaporated and the dry salts dissolved again in 

 the least possible amount of water, and boiled as before with 

 30cm 3 of amyl alcohol. The barium salt was filtered off into a 

 perforated platinum crucible containing an asbestos felt, dried 

 and weighed as previously described. The calcium was deter- 

 mined in the filtrate, in the form of the sulphate, by evapora- 

 tion of the alcohol, treatment with an excess of sulphuric acid 

 and ignition. Series II gives the results of this treatment. 



In Series III the effect of a double treatment with the alco- 

 hol is recorded. In these experiments, after the first boiling, 

 already described, the alcohol was decanted upon an asbestos 

 felt, under the conditions previously mentioned, and collected 

 in a beaker placed to receive it. The residue was then dried 

 at a gentle heat over a radiator to remove amyl alcohol, dis- 

 solved in a few drops of water, and this solution was treated 

 with a drop of dilute nitric acid to assure the condition of 

 nitrate, and evaporated to dryness. After dissolving in a few 

 drops of water, 30cm 3 of alcohol were added, and the boiling 

 repeated. The residue was filtered off upon the felt through 

 which the first portion had been decanted and washed with 

 amyl alcohol, care being taken to remove all particles from the 

 beaker by careful rubbing. The crucible and residue were 

 heated to 150° C. as before and weighed. The results after 

 one treatment are fully as satisfactory as those after the double 

 treatment, — a point which simplifies the method considerably. 

 In the separation of strontium from calcium the double treat- 

 ment was necessary. The form in which the salts separate 

 suggested a possible explanation. The strontium nitrate sepa- 

 rates in plate-like masses, while the barium is much more 

 granular and therefore less liable to include foreign matter. 



Series IY contains the results of certain experiments directed 

 toward the separation of barium and strontium together from 

 calcium. Definite portions of the three nitrate solutions were 

 measured into counterpoised beakers and the successive weights 

 taken as previously described. The method of treatment was 

 the same as that described in the double treatment of the 

 barium and calcium salts. The correction for the solubility of 

 the strontium salt was applied (O'OOl grm. of strontium oxide 

 to 30cm 3 of the alcohol used) in the manner defined in the paper 

 upon the separation of strontium from calcium. The results 

 are tabulated for the nitrates in the cases in which barium and 

 strontium were treated together, but the errors are also aver- 



