BROMOBENZOIC ACID. 857 



it is more soluble than the former salt, but crystallizes with 

 difficulty in a regular form. It will be observed that hyposul- 

 phobenzoic acid is formed by the abstraction of the elements of 



1 atom of water from 1 atom of benzoic acid and 2 atoms sul- 

 phuric acid, and that it retains the saturating power of 2 atoms 

 of acid, being bibasic. 



Nitrobenzoic or benzoenitric acid, HO + C 14 H 4 O 3 , NO 4 ; an 

 acid formed by the abstraction of HO from the elements of 

 nitric acid and benzoyl. It is prepared by boiling benzoic acid 

 with an excess of nitric acid, the first is dissolved and colours 

 the fluid red ; deutoxide of nitrogen is evolved as an accidental 

 product arising from the action of the nitric acid on the nitro- 

 benzoic acid already formed. From the cold solution crystals 

 similar to benzoic acid are deposited ; the fluid eventually 

 becomes a solid crystalline mass. At 50, 400 parts of water 

 dissolve 1 part of the acid, at 212 10 parts. It dissolves easily 

 in alcohol and ether ; fuses at 2GO.6 (127 centig.), but begins 

 to sublime at 230 ; the pure acid sublimes unchanged ; chlorine 

 has no action upon it. 



The nitrobenzoates are for the most part soluble in water and 

 alcohol, crystallizable, explode by heating, and when gently 

 warmed give off nitrobenzide (C 12 H 5 NO 4 ). Ammonia forms a 

 neutral and acid salt. The salt of lime is acicular and contains 



2 atoms of water, which are driven off at 374. The salt of 

 barytes loses 4 atoms of water at 212. The salt of strontian 

 loses 2f equivalents of water at 266. When acid nitroben- 

 zoate of ammonia is added to a solution of sulphate of zinc, a 

 gelatinous basic salt precipitates, containing 4 atoms of oxide 

 of zinc to 1 atom of acid. The filtered solution gives the 

 neutral salt of zinc in crystalline plates, w r hich contain 5 atoms 

 of water. The salt of copper is a blue powder soluble in hot 

 water, containing 1 atom of water. Besides a neutral nitroben- 

 zoate of lead, a remarkable sub-salt exists, in which 1 atom of 

 oxide of lead is united with 5 atoms of the neutral salt. Nitro- 

 benzoic acid forms fine crystallizable compounds with both 

 oxide of ethyl and oxide of methyl. (Mulder, Mitscherlich.) 



Bromobenzoic acid, 2HO-fC 28 H 9 BrO 8 ; a bibasic acid, dis- 

 covered by Peligot ; and formed by the action of 4 atoms of 

 bromine upon 2 atoms of benzoate of silver : 



4Br=C 28 H 9 BrO 8 and 2AgBr and HBr. 



