M. Schwanert on the Action of Nitric Acid on Camphor, 503 



and this body also seemed to result from the action of sodium- 

 amalgam on nitrobenzamide. 



When a solution of azobenzoate of soda in excess of caustic 

 soda was boiled with solution of green vitriol, hydrated oxide of 

 iron was formed at first, which speedily changed into black pro- 

 tosesquioxide of iron on the addition of more solution of protoxide. 

 The solution was feebly yellow, and on the addition of an acid a 

 yellowish white precipitate was formed, which Strecker calls hy- 

 drazobenzoic acid. It is nearly insoluble in boiling water, and dis- 

 solves in alcohol with difficulty, but sufficiently so for recrystalli- 

 zation, by which it is obtained in yellowish white indistinct 

 flakes. It has the formula C 14 H 6 NO 4 , differing from azobenzoic 

 acid by containing an additional atom of hydrogen. 



The new acid readily dissolves in the alkalies with a clear 

 yellow colour, but on standing in the air these solutions rapidly 

 absorb oxygen and are converted into the azobenzoates. When 

 boiled with strong hydrochloric acid, hydrazobenzoic acid is de- 

 composed into azobenzoic acid and hydrochlorate of amidobenzoic 

 acid. The decomposition is expressed as follows : — 



2C 14 H 6 NO 4 =C l4 H 5 N0 4 + C 14 H 7 N0 4 . 



Hydrazobenzoic Azobenzoic Amidobenzoic 

 acid. acid. acid. 



Schwanert* has published the results of a lengthened investi- 

 gation on the action of nitric acid on camphor, etherial oils, and 

 resins. In the case of camphor, about half a pound was heated 

 with ten to twelve times its weight of nitric acid, with frequent 

 cohobation, for about twenty hours. By this time the camphor had 

 completely disappeared, and the disengagement of nitrous fumes 

 had almost entirely ceased. When the liquid was evaporated to 

 about one half, camphoric acid crystallized out, and on further 

 evaporation it yielded another crop of crystals, while a mass was 

 left in all respects resembling Venetian turpentine. Besides 

 these products, water and carbonic acid were also formed. 



The above mass Schwanert found to consist essentially of a 

 new tribasic acid, the formula of which is € 10 H 14 7 , and which 

 is formed not only from camphor, but also from etherial oils and 

 resins. Schwanert names it camphresic acid. It is purified by 

 solution in water, neutralization with ammonia, and partial pre- 

 cipitation with acetate of lead, by which the whole of the 

 camphoric acid is first precipitated j this is filtered off, the pre- 

 cipitation completed by acetate of lead, the precipitate decom- 

 posed by sulphuretted hydrogen ; the liquid, filtered off from the 

 sulphide of lead and evaporated, leaves camphresic acid in a state 

 of purity. 



* Liebig's Annalen, October 1863. 



