17-i TROCEEDINGS OF THE AMERICAN ACADEMY 



Angles between Normals. 



Action of Phosphoric Pentabromide and Acetylchloride. 



Mr, O. R. Jackson studied with me tlie behavior of mucobromic 

 acid towards phosphoric pentabromide and acetylchloride. 



Mucubromi/lbromide . When mucobromic acid is mixed with about 

 four times its weight of phosphoric pentabromide, and the mix- 

 ture heated for a short time at 110-115°, a quiet reaction sets in, 

 the mass becomes liquid, and water then precipitates a heavy red oil, 

 which after thorough washing with water gradually solidifies at ordi- 

 nary temperatures, or immediately if cooled to 0°. This substance is 

 very soluble in alcohol, ether, benzol, chloroform, or carbonic disul- 

 phide, but crystallizes well from a solution in a little hot alcohol 

 when this is cooled to 0°. After repeated crystallization from alcohol, 

 it forms small, slender prisms, which melt at 55-56°, and have the 

 percentage composition corresponding to mucobromylbromide. 



I. 0.6643 grm. substance gave 0.3755 grm. COg and 0.0374 grm. 



ILO. 

 II. 0.2598 grm. substance gave 0,4573 grm. AgBr. 

 lU. 0.2252 grm. substance gave 0.3964 grm. AgBr. 



m. 



74.89 



♦ The form { 100 } was observed upon two or three individuals only, and the 

 reflections were imperfect. 



