62 ^Appendix. 



The Anisic series is closely related to the oil of anise (Pim- 

 pinella Anisum and Illicium A.). 



The benzene nucleus has not been traced in many of the 

 alkaloids. Atropia, however, yields an isomer of cinnamic acid, 

 and it is conjectuial that other alkaloids of the Solanaceae con- 

 tain the benzene nucleus. 



In the Summary of Wittstein, before mentioned, T 2 T 6 or 22 

 per cent, of the natural orders contain aromatic bodies terpenes 

 and resins not being included as such. 



After this slight survey of the constitution and natural dis- 

 tribution of the aromatic bodies, we will next consider what has 

 been accomplished in their artificial synthesis. 



Benzene itself, it will be observed, is a polymer of acety- 

 lene, C 2 H 2 . And by heat, in a bent tube over mercury, 

 acetylene (13 times denser than hydrogen) is transformed into 

 benzene (39 times denser than hydrogen). Acetylene is formed, 

 from the elements carbon and hydrogen, in the electric arc, 

 with a strong battery (one of 40 or 50 Bunsen's elements giving 

 100 c.c. of the gas per minute( 16 ). Also from marsh gas, or 

 from carbon disulphide with carbon monoxide, by electric dis- 

 charge. 



Toluene is formed from benzene, (i) by action of methyl 

 iodide and sodium (Fittig and Tollens), (2) by marsh gas when 

 both it and the benzene are nascent (Berthelot)( 17 ). In the last 

 reaction, Xylene and Cumene are also produced. 



In these and other ways all the hydrocarbons expressed with 

 the single hexagon may be synthesized from benzene. Naphtha- 

 lene, of the double hexagon, is formed on passing toluene through 

 a white-hot tube (Berthelot)( 18 ). 



It is familiar to every one that these hydrocarbons, with the 

 phenols and many other aromatic compounds, are formed every 

 .day in every town from coal, by distillation at ten or twelve hun- 



(16) BERTHEIA>T: Compt. Rend., IV, 640; Watts' Diet., 1st Sup., 30, 31. 



(17) C 6 H 6 +CH 4 =C 7 H 8 + H 2 . 



(18) 4C 7 H 8 =C 10 H 8 +3C C H 6 +3H 2 . 



