314 



PRACTICAL ORGANIC AND BIO-CHEMISTRY 



and from these a larger number of isomers, menthadienes, containing two- 

 double bonds, e.g. 



Further, instead of forming the second double bond between two adjacent 

 carbon atoms union may be formed between the carbon atoms 8 and 3, 8 and 

 2, 8 and i, thus * 



or 



or 



i i i 



The chief terpenes and their oxygen derivatives are classified in several 

 groups and have been found to possess the following structural formulae : 



Menthane Group. 



CHo CH 



CHg 



Carvomenthol. 



CH g 



Carvomenthone. 



