444 



VI. " Contributions to the History of Aniline, Azobenzole and 

 Benzidine." By A. W. HOFMANN, Ph.D., F.R.S. Re- 

 ceived May 30, 1855. 



The transformation of nitrobenzole into aniline by the action of 

 sulphuretted hydrogen is attended with such difficulties and requires 

 especially so much time, that chemists hitherto have generally pre- 

 ferred to prepare this base from indigo. Lately a new modification 

 of Zinin's process has been adopted by M. A. Be'champ*, which 

 consists in submitting nitrobenzole to the reducing action of acetate 

 of protoxide of iron. This process M. Be'champ simply uses a 

 mixture of iron and acetic acid is applicable to all nitro-compounds, 

 and has been extensively tried with the most perfect success in the 

 laboratory of the Royal College of Chemistry. The facility of the 

 process, its rapidity, and the large amount of product it yields in 

 most cases, cannot fail materially to assist the study of the volatile 

 organic bases. 



During these experiments several observations were made, which 

 I beg leave to bring under the notice of the Society. 



When employing about double the amount of iron which is recom- 

 mended by M. Be'champ (2 '5 instead of 1'2 of iron to 1 part of 

 nitrobenzole), Mr. Alfred Noble found that the latter portion of the 

 distillate solidified partly in the receiver and partly in the condenser. 

 Washed with hydrochloric acid from adhering aniline, and once or 

 twice recrystallized from boiling alcohol, the solid matter was ob- 

 tained in fine crystals of a yellowish-red colour, and fusing below 

 the boiling-point of water. These crystals possessed all the proper- 

 ties of azobenzole, which was moreover identified by combustion. 



0'260 gramme of substance gave 0'755 grm. of carbonic acid 

 and 0' 1 34 grm. of water. 



The well-established formula of azobenzole, C I2 H 5 N, requires the 

 following values : Theory. 



100-00 



* Annales de Chimie et de Physique, (3) torn. xlii. 186. 



