OP ARTS AND SCIENCES. 177 



required by a barium salt of dibrommaleic acid containing two mole- 

 cules of water of crvstallization. 



I. 0.8687 grm. of substance lost, at 120°, 0.0G24 grm. II^O. Of 

 this dried salt, 0.414^ i^rm. gave, by ignition, 0.2341 grm. 

 BaSO,. 

 II. 0.5780 grm. of air-dried salt gave, by ignition, 0.3010 BaSO^. 



Calculated for BaCiBrjO^ . 2 HjO. Found. 



This salt is hardly more soluble in boiling water than in cold ; in 

 dilute alcohol, it is almost insoluble. The solubility in water was de- 

 termined according to the method of V. Meyer. 



I. 7.1377 grm. of a solution saturated at 19° gave, on evaporation 



with H^SO, and ignition, 0.2296 grm. BaSO^. 

 II. 6.9649 grm. of a solution saturated at 19° gave 0.2249 grm. 

 BaSO,. 



An aqueous solution saturated at 19°, therefore, contains of the 

 anhydrous salt the percentages : — 



I. II. 



5.65 5.67 



The silver salt could best be made by the precipitation of a solution 

 of the free acid by argentic nitrate. From dilute solution, it separated 

 in long, flat needles ; from concentrated solutions, it was precipitated 

 in small prisms. It proved to be almost insoluble even in hot water. 

 The dry salt exploded violently on heating, or by percussion. 



0.6311 grm. of the salt, dissolved in dilute nitric acid, gave 0.4859 

 grm. AgBr. 



Calculated for AgoC4Br204. Found. 



Ag 44.27 44.22 



The lead salt fell as a crystalline precipitate upon the addition of 

 plumbic acetate even to a dilute solution of the free acid. 



The acid was liberated from the pure barium salt by the addition of 

 normal sulphuric acid, in quantity insufficient for complete precipita- 

 tion; the aqueous solution was allowed to evaporate spontaneously ; and 

 the acid >vas then separated from the excess of barium salt by means 

 of ether free from alcohol. Prepared in this way, the acid formed a 



VOL. XVI. (n. S. VIII.) 12 



