Dr. Hofmann on the Metamorphoses of Indigo. 509 



dissolved in spirits of wine, a white crystalline precipitate is 

 formed. This was separated by filtration, and recrystallized 

 from boiling water. The crystals formed on cooling were in- 

 distinct in form, and with difficulty soluble in alcohol and 

 water; insoluble in aether. The combustion of a portion dried 

 at the ordinary temperature gave the following results : — 



0'5t)35 grm. of the oxalate gave 0'804'5 grm. of carbonic 

 acid and 0*1695 grm. of water. These numbers correspond to 



the formula CgOg, C,2 ^ t>? r N + HO, as is seen by a com- 

 parison of the theoretical and experimental numbers. 



Theory. Experiment. 



So that the brominated base forms, like aniline, the neutral 

 oxalate under the same circumstances in which the acid salt 

 of chloraniline is obtained. 



Hydrochlorate of Bromaniline. CI H, Cj 



HA 

 Br J 



N. 



This salt, which is obtained directly by dissolving broma- 

 niline in hydrochloric acid, crystallizes on cooling from its 

 hot saturated solution in a radiating filamentous mass. By 

 slow evaporation of the solution over sul- 

 phuric acid, large well-formed crystals can 

 be procured. 



According to the determination of Dr. 

 T. Mliller, these crystals belong to the 

 monoclinometric system (system hemior- 

 thotype of Mohs). 



The angle which is formed by the hori- 

 zontal axis b and a is = 90°. The axis c 

 forms with a a right, and with b\ an ob- 

 lique angle. 



Names of the planes : — 



c= c : oo a : QO b 



d=: a : c : CO b 



g— a : b : "X) c 



2g=2a : b x <x> c 



