190 PROCEEDINGS OP THE AMERICAN ACADEMY 



Acid Baric §-Sulphopyromucate, Ba(C 5 H 3 S0 6 )„ . 4 H 2 and 6 H 2 0. — 

 Although this salt may be formed by the action of hydrochloric acid 

 upon the neutral salt, its ready solubility in cold water makes it more 

 conveniently prepared from equivalent quantities of the free acid and 

 the neutral salt. On cooling the concentrated solution, the salt sepa- 

 rates in long slender prisms containing six molecules of water. From 

 more dilute solutions, when crystallization begins at ordinary tempera- 

 tures, the salt separates in well-formed rhombic plates which contain 

 four molecules of water. Not unfrequently both forms appear to- 

 gether, and we have not been able to determine with precision the 

 conditions essential to the formation of either. The long slender 

 prisms effloresce slowly when exposed to the air. When dried by 

 pressure and by short exposure to the air, it gave the following 

 results : — 



I. 0.6298 grm. of the salt lost, at 100°, 0.1056 grm. H 2 0. 

 II. 1.7845 grm. of the salt lost, at 120°, 0.3055 grm. H 2 0. 



Calculated for Found. 



Ba(C s H 3 S0 c ) 2 .6H 2 I. II. 



H 2 17.22 16.77 17.12 



I. 0.5242 grm. of the salt dried at 100° gave 0.2361 grm. BaS0 4 . 



IL 0.7035 grm. of the salt dried at 120° gave 0.3155 grm. BaS0 4 . 



III. 0.7629 grm. of the salt dried at 120° gave 0.3420 grm. BaS0 4 . 



Ba 



The rhombic plates did not lose in weight when exposed to the air, 

 and but slowly over sulphuric acid. The air-dried salt gave the 

 following results : — 



I. 4.3735 grm. of the air-dried salt lost, at 105°, 0.5235 grm. H 2 0. 



II. 1.4496 grm. of the air-dried salt lost, at 105°, 0.1762 grm. H 2 0. 



III. 1.6332 grm. of the air-dried salt lost, at 135°, 0.2010 grm. H 2 0. 



H 2 



I. 0.6969 grm. of the salt dried at 105° gave 0.3125 grm. BaS0 4 . 



II. 0.6325 grm. of the salt dried at 140° gave 0.2825 grm. BaS0 4 . 



III. 0.5982 grm. of the salt dried at 140° gave 0.2682 grm. BaS0 4 . 



Ba 



