OF ARTS AND SCIENCES. 317 



acid in vacuo. The viscous residue thus obtained gradually solidified 

 at low temperatures, and yielded tolerably well formed thick prisms 

 with bevelled ends. The substance, freed from the viscous mother 

 liquors as completely as possible and dried over sulphuric acid, gave, 

 on analysis, the following results : — 



I. 0.7181 grm. substance gave 0.6451 grm. CO., and 0.1004 grm. 



HoO. 

 II. 0.7504 grm. substance gave 0.6697 grm. COg and 0.1010 grm. 



HoO. 



III. 0.2053 grm. substance gave 0.1977 grm. AgBr. 



IV. 0.2348 grm. substance gave 0.2254 grm. AgBr. 



round. 



III. IV. 



C 

 H 

 Br 41.03 41.00 40.86 



Mucoxybromic acid is extremely soluble in water, alcohol, or ether, 

 and almost insoluble in chloroform, benzol, ligroin, or carbonic disul- 

 phide. The melting point was found to be 111-112° ; the true melt- 

 ing point may, however, be somewhat higher, since the substance could 

 not be purified by repeated crystallization. The acid gives with ferric 

 chloride an intense garnet-red coloration, which is readily seen, even 

 in very dilute solutions. With argentic nitrate it gives a white crys- 

 talline precipitate of the silver salt. Baric acetate added to a concen- 

 trated aqueous solution throws down the highly crystalline barium 

 salt. By the action of hydrobromic acid saturated at 0°, or of phos- 

 phoric pentabromide, no definite products were obtained. 



Baric Mucoxybr ornate, BaC^HBrO^ . 2 H^O. — The preparation of 

 the barium salt has already been described. The salt is somewhat 

 sparingly soluble in cold water, and its solubility is not sensibly in- 

 creased by heat. It is rapidly decomposed by boiling its aqueous 

 solution, and even in the cold decomposition ensues after long stand- 

 ing. On the evaporation of a solution saturated at ordinary tempera- 

 tures over sulphuric acid in vacuo, the salt separates in long lustrous 

 six-sided prisms, with perpendicular terminations. The air-dried salt 

 loses over sulphuric acid, or at 100°, rather more than one mole- 

 cule of water, and has then the composition BaC^HBrO^ . H^O. 

 When heated to 105-115°, it slowly loses the second molecule of 

 water, but at the same time it turns brown, and baric bromide is 

 formed. 



