296 CONSIDERATION OF CARBON COMPOUNDS. 



On the. average, aromatic compounds are richer in carbon 

 than fatty compounds, and yield, when decomposed by various 

 methods, benzene as one of the products ; most aromatic sub- 

 stances have antiseptic properties. The following graphic 

 formulas may serve to illustrate the constitution of some aro- 

 matic substances: 



II 



i A 



Benzaldehyde, Salicylic acid. Gallic acid, 



or bitter almond oil. 



HO HO 



H \ /^ / C \\ 



\C X ^C CO O C X ^ 



HO C H HO^C' 



A A 



Digallic acid or tannic acid. 



