216 PROCEEDINGS OF THE AMERICAN ACADEMY 



III. 0.5901 grm. of the air-dried salt gave 0.3981 grm. BaS0 4 . 



IV. 0.8840 grm. of the air-dried salt lost, at 160°, 0.0484 grm. H 2 0. 



I. 0.6005 grm. of the salt dried at 165° gave 0.4270 grm. BaS0 4 . 

 II. 0.6010 grm. of the salt dried at 165° gave 0.4269 grm. BaS0 4 . 



Ba 



la determining the solubility of the barium salt in cold water, we 

 evaporated its solution rapidly until crystals began to appear, and then 

 cooled with constant stirring. Abundant crystals of the salt were 

 thus formed. In order to satisfy ourselves that solutions of constant 

 composition could be obtained in this way, we made four separate 

 determinations. 



I. 16.2601 grm. of the solution saturated at 21° gave 0.2172 grm. 



BaS0 4 . 

 II. 14.4321 grm. of the solution saturated at 21° gave 0.1950 grm. 

 BaS0 4 . 



III. 12.1256 grm. of the solution saturated at 21° gave 0.1646 grm. 



BaS0 4 . 



IV. 12.7701 grm. of the solution saturated at 21° gave 0.1788 grm. 



BaS0 4 . 



The aqueous solution of barium salt saturated at 21°, therefore, con- 

 tained the following percentages of the anhydrous salt : — 



I. II. III. IV. 



1.88 1.90 1.91 1.96 



Acid Baric fi-Sulphopyromucate, Ba(C 5 H„S0 6 ) 2 . 3 H.,0. — This 

 salt may be made by dissolving the neutral barium salt in hydrochloric 

 acid, or, more advantageously, by mixing solutions of the neutral ba- 

 rium salt and the free acid in equivalent quantities. It is readily solu- 

 ble in hot water, more sparingly in cold water, and crystallizes in 

 small obliquely truncated prisms, which are permanent in the air. 



I. 1.4255 grm. of the air-dried salt lost, at 130°, 0.1403 grm. H,0. 

 II. 1.3386 grm. of the air-dried salt lost, at 135°, 0.1271 grm. H 2 0. 

 III. 0.5371 grm. of the air-dried salt gave 0.2193 grm. BaS0 4 . 



