198 PROCEEDINGS OP THE AMERICAN ACADEMY 



0.4608 grm. of the salt dried at 135° gave 0.1973 grm. CaS0 4 . 



Calculated for 

 CaC 6 HBrS0 6 . Found. 



Ca 12.94 12.60 



Plumbic P-Brom-h-Sulphopyromiicate, PbC 5 HBrS0 6 . 4 H 2 0. — The 

 lead salt is freely soluble in hot water, more sparingly in cold water, 

 and crystallizes in flat clustered prisms, or on rapid cooling in clus- 

 tered needles. The air-dried salt contains four molecules of water, 

 almost the whole of which it rapidly loses over sulphuric acid. 



I. 1.3814 grm. of the air-dried salt lost, at 130°, 0.1758 grm. H 2 0. 

 II. 1.9209 grm. of the air-dried salt lost, at 140°, 0.2507 grm. H 2 0. 



III. 0.3442 grm. of the air-dried salt gave 0.1905 grm. PbS0 4 . 



IV. 0.6382 grm. of the air-dried salt gave 0.3530 grm. PbS0 4 . 



IV. 



37.79 



Potassic fi-Brom-S-Sulphopyromucate, K 2 C 5 HBrS0 6 . \\ H 2 (?). — 

 This salt is readily soluble in cold water, more sparingly soluble in 

 dilute alcohol. It crystallizes in small six-sided plates which are 

 permanent in the air, but which effloresce over sulphuric acid. Two 

 determinations of the water of crystallization made in different prep- 

 arations agree precisely with each other, but do not correspond well 

 with any simple formula for the salt. 



I. 0.8184 grm. of the air-dried salt lost, at 160°, 0.0537 grm. H 2 0. 

 II. 1.4398 grm. of the air-dried salt lost, at 160°, 0.0942 grm. H 2 0. 



0.3652 grm. of the salt dried at 160° gave 0.1825 grm. K 2 S0 4 . 



Calculated for 



K 2 C 6 HBrS0 6 . Found. 



K 22.52 22.44 



The connection between this brom-sulphopyromucic acid and the 

 8-sulphopyromucic acid could evidently be proved most neatly and di- 

 rectly by eliminating from it the bromine, and examining carefully the 

 sulphonic acid thus formed. By warming a strongly ammoniacal solu- 

 tion of the barium salt with zinc dust the bromine was quickly removed. 



