Gooch and Soderman — Barium and Strontium. 539 



water and treatment with 50 cm 3 -75 cm 3 of such a mix- 

 ture is practically negligible, while strontium chloride 

 equivalent to 0-3 grm. of the anhydrous salt, dissolved in 

 the least possible amount of water and treated with the 

 mixture, first yields a characteristic precipitate of crys- 

 talline needles and then dissolves completely when the 

 volume of the precipitating mixture has been sufficiently 

 increased and before this has reached the 75 cm 3 limit. 

 The precipitate of barium chloride formed when only 

 barium chloride is similarly treated is coarsely granular 

 and fails to dissolve upon further addition of the 

 precipitant up to the limit named. 



When a solution of barium chloride and strontium 

 chloride in the least possible amount of water is similarly 

 treated with a considerable volume of the acid-ether 

 mixture the former salt is completely precipitated and 

 the latter may be partially precipitated at first and, 

 excepting any inclusion in the barium chloride, go into 

 solution later as the volume of liquid is increased; but 

 if the precipitating mixture is added slowly to the solu- 

 tion of the mixed chlorides, drop by drop for the first few 

 cubic centimeters, the liability of the strontium chloride 

 to precipitation and inclusion is minimized. 



In the practical application of the method elaborated 

 upon these lines, the solution of the mixed chlorides in 

 the least possible amount of water may be accomplished 

 most easily by adding to the dry salts, contained in a 

 beaker, a very little water (beginning with about 0*2 

 cm 3 and, if necessary, adding more later), and warming 

 gently, with agitation, and then cooling. If crystals 

 separate on cooling, the operation is cautiously repeated 

 until a cold saturated solution is obtained. 



The precipitation is begun by adding the acid-ether 

 mixture to the cold saturated water solution of the mixed 

 salts, drop by drop and with constant agitation during 

 the addition of the first two or three cubic centimeters of 

 the precipitant. Thereafter the precipitant is added in 

 amounts necessary to complete the precipitation of the 

 barium chloride and dissolve the strontium chloride — 50 

 cm 3 to 75 cm 3 for amounts not exceeding 0-5 grm. of the 

 mixed salts nor 0-3 grm. of anhydrous strontium chloride. 

 The liquid is decanted upon asbestos in the perforated 

 crucible. The residue, washed and transferred to the 

 filter with a 4 : 1 mixture of concentrated hydrochloric 



