OF ARTS AND SCIENCES. 207 



retains a slight yellow or greenish color. The purification of this 

 neutral salt is still further rendered difficult by the fact that a hot 

 saturated solution of the salt deposits little or nothing on cooling, and 

 recrystallization therefore involves the evaporation of comparatively 

 large quantities of liquid. The purification may be more conveniently 

 effected by conversion into the more soluble acid salt, or by preparing 

 the acid salt at the outset. The acid salt may easily be made by dis- 

 solving the neutral salt in hydrochloric acid somewhat diluted with 

 water, and removing by recrystallization the baric chloride formed. 

 From a solution of the acid salt the neutral salt may again be precipi- 

 tated by the addition of baric acetate, or of course by the addition of 

 amnionic hydrate and the necessary quantity of baric chloride. The 

 free acid made from the barium salt by exact precipitation with sul- 

 phuric acid forms oblique flat prisms or plates, which deliquesce in 

 moist air. 



Baric fi-Sidpho-b-brompijromiicate, BaC 5 HBrSO c . 5 H 2 0. — The 

 barium salt is sparingly soluble in hot or cold water, and crystallizes 

 in clear six-sided, clustered prisms. Its aqueous solution is precipi- 

 tated by the addition of alcohol. The salt contains five molecules of 

 water, four of which it loses slowly on exposure to the air, or more 

 rapidly when heated to 100°. 



I. 2.1588 grm. of the salt dried by short exposure to the air lost, at 

 162°, 0.3806 grm. H 2 0. 

 II. 1.1795 grm. of the salt dried by short exposure to the air lost, at 

 170°, 0.2010 grm. H 2 0. 



Calculated for Found. 



BaC 5 HBrS0 . 5 H 2 0. I. II. 



II 2 18.14 17.63 17.88 



I. 1.8574 grm. of the salt dried at 100° lost, at 162°, 0.0792 grm. H 2 0. 

 II. 0.7262 grm. of the salt dried at 100° lost, at 160°, 0.0317 grm. H 2 0. 



I. 0.6945 grm. of the salt dried at 160° gave 0.3980 grm. BaS0 4 . 



II. 0.7840 grm. of the salt dried at 140° gave 0.4500 grm. BaS0 4 . 



III. 0.7825 grm. of the salt dried at 140° gave 0.4495 grm. BaS0 4 . 



Ba 



