Separation of Strontium from Galcium. 51 



nitric acid, and making up to measure. In the earlier experi- 

 ments other methods of purification were used, such as the 

 precipitation of the strontium nitrate by alcohol, and in case 

 of the calcium salt the preparation of the nitrate from the 

 carbonate precipitated by ammonium carbonate from a solu- 

 tion of calcium sulphate. The method first described, however, 

 gave satisfactory results, the spectroscope failing to show in 

 the product thus obtained any trace of intermixture of calcium 

 and strontium salts, or the presence of any other appreciable 

 impurity. In the determination of the standards of these solu- 

 tions definite amounts were drawn off from burettes into 

 counterpoised beakers or crucibles (according as the method of 

 determination was by precipitation or evaporation) and weighed 

 as a check on the burette reading. The strontium nitrate in 

 each portion was converted into the sulphate either by pre- 

 cipitation in the presence of alcohol, or by evaporating and 

 igniting , these methods yielding results closely agreeing. The 

 calcium was determined by evaporation with sulphuric acid. 

 The first series of experiments was directed toward an investi- 

 gation of the action of amyl alcohol upon strontium nitrate 

 alone. Accordingly several amounts of the strontium salt were 

 measured from a burette into counterpoised Bohemian beakers 

 of about 100 cm 3 capacity, and weighed. The water was 

 then evaporated over a water bath, and the dry salts dissolved 

 in a few drops of water and boiled with 30 cm 8 of amyl alco- 

 hol, that amount being determined upon for convenience. 

 Care should be taken not to add more than the necessary 

 amount of water to dissolve the salt, inasmuch as the presence 

 of much water delays the process (it being necessary to expel 

 all the water before the amyl alcohol can do its work) and 

 tends to cause spattering due to the superheating of the water 

 and consequent sudden generation of steam under the alcohol. 

 It has been my experience that in the presence of a few drops 

 of water the boiling goes on quietly, the water escaping easily 

 through the amyl alcohol, so that in the course of a few 

 minutes the alcohol reaches its normal boiling temperature 

 (128°-130° C.) In order that the inflammable fumes of the 

 alcohol might not reach the flame during the boiling the 

 beaker was placed upon a piece of asbestos board about 15 cm. 

 square. When the temperature of the alcohol reached its 

 normal boiling point (128° — 130° C), as shown by a thermom- 

 eter, the beaker was removed and the strontium nitrate filtered 

 off upon an asbestos felt in a perforated platinum crucible, the 

 crucible and felt having been previously dried and weighed. 



The filtration was carried on under gentle pressure, the fil- 

 trate being received in a beaker standing under a bell jar upon 

 a ground glass plate. The last traces of strontium nitrate 



