Note 26 — Chapter VIII · CARBON AND THE HYDROCARBONS

The conception of homology has been applied by Gerhardt to all organic compounds in his classical work, ‘Traité de Chimie Organique,’ finished in 1855 (4 vols.), in which he divided all organic compounds into fatty and aromatic, which is in principle still adhered to at the present time, although the latter are more often called benzene derivatives, on account of the fact that Kekulé, in his beautiful investigations on the structure of aromatic compounds, showed the presence in them all of the ‘benzene nucleus,’ C6H6.