at the Royal Institution, 1 900-1 907. 



373 



mutual influence, without, however, directly entering into combina- 

 tion. The symbol is written — 



H C 

 H C/ 



/C H 



/ I or simply 



\C H 



Benzene is one of the hydrocarbons which are produced in 

 manufacturing gas by heating coal ; other hydrocarbons formed at 

 the same time are naphthalene and anthracene. It is now established 

 that naphthalene, CjqHs, may be regarded as formed by the fusion of 

 two and anthracene, C14H12, of three benzene rings, thus — 



Benzene 



Naphthalene 



Anthracene 



More complex hydrocarbons than these containing larger propor- 

 tions of carbon and smaller proportions of hydrogen are present in 

 coal tar, all of which apparently are built up in a similar manner : 

 it would seem, indeed, that the formation of carbon from the simpler 

 hydrocarbons involves not only the gradual loss of hydrogen but also 

 a correlative growth in complexity, due to the fusion of ring upon 

 ring in the manner illustrated in formulae such as the above. 



