WHICH NITROGEN IS SUBSTITUTED FOR HYDROGEN. 
673 
0-3025 grm. of the substance gave, on precipitation with nitrate of silver, 0-304 grm. 
of bromide of silver, corresponding to 43-3 per cent, of hydrobromic acid. 
Calculated. 
Found. 
, 104 
56-22 
— 
rH 
OO 
43-78 
43-30 
185 
100-00 
Hydrobromate of diazobenzol crystallizes in white nacreous scales, which, like the 
compound previously described, are readily soluble in water, less so in alcohol, and inso- 
luble in ether. The solution of this compound is distinguished by a strong acid reac- 
tion. Heat, friction, and pressure cause the crystals of the hydrobromate to explode 
with the same violence as the nitrate of diazobenzol. Even when in a perfectly dry 
state this compound can only be kept for a short time without undergoing decomposition 
(which is accompanied by the production of a peculiar aromatic odour), the decomposition 
being complete in a few days. It is formed according to the equation 
G 12 H n N 3 + 6Br=G 6 H 4 N 2 , HBr+G 6 H 4 Br 3 N+2HBr. 
Diazo-amido- Hydrobromate of Tribromaniline. 
benzol. diazobenzol. 
Tribromaniline remains in the ethereal mother-liquor, from which it crystallizes on 
evaporation. 
It is most likely that, by the action of chlorine upon diazo-amidobenzol, hydrochlorate 
of diazobenzol may be obtained. An aqueous solution of this latter compound, how- 
ever, may also be prepared by treating a solution of the hydrobromate with moist chloride 
of silver. 
Perbromide of Biazobenzol, G 6 H 4 N 2 , HBr, Br 2 . 
On adding a small quantity of bromine-water to an aqueous solution of the nitrate of 
diazobenzol, a white crystalline precipitate of tribromophenylic acid is usually obtained, 
owing to the presence of a small quantity of phenylic acid formed by the spontaneous; 
decomposition of the nitrate by water. On removing the tribromophenylic acid as 
quickly as possible by filtration, and on the addition of a large excess of bromine-water 
containing free hydrobromic acid to the filtrate, the new bromine-compound separates 
as a brownish-red oil, which solidifies to a crystalline mass soon after the supernatant 
liquor has been removed. The crystals are obtained pure for analysis by washing with 
a little ether. 
I. 0-7154 grm. gave 0-5504 grm. G0 2 , corresponding to 20-98 per cent, of carbon and 
1-60 of hydrogen. 
II. 0-4805 grm. of this substance, digested with excess of aqueous ammonia'*, gave, on 
expulsion of the excess of ammonia and precipitation with nitrate of silver, 0-8005 grm. 
of bromide of silver, corresponding to 70-68 bromine per cent. 
* The transformation which this substance thus undergoes, and which renders it possible to determine the 
bromine in this manner, will be fully explained further on. 
