210 THE CONSTITUENTS OF PLANTS. IX. 



H 



CH. 2 C CH 2 



CH 3 C CH.. 

 CH 2 -C- -CO 



CH, 



Aschan* has, quite recently, proved the correctness of this 

 formula. 



Camphor is obtained by distilling, in steam, the wood and 

 bark of Laurus camplwra. It is a colourless crystalline solid, 

 melting at 175 and boiling at 204. It is produced by the 

 oxidation of some terpenes. 



Phenols. Thymol, C,H 3 (CH H ).(C 3 H 7 ).OH, in oil of thyme. 



(1) (4) (3) 



Eugenol, C fi H 3 (C 3 H 5 )(OCH 3 ).OH, in oil of cloves. 



(1) (3) (4) 



Carvacrol, C (i H 3 (CH 3 )(C 3 H 7 ).OH, in oil of hops. 



;(i) (4) (2) 



Thymol, which may be taken as typical of the group, is a 

 crystalline body melting at 50 and boiling at 230. It is 

 possessed of antiseptic properties and in solution in alcohol is 

 sometimes used in veterinary medicine as a vermifuge. 



Among other oxygen-containing bodies of this class may be 

 mentioned coumarin, the anhydride of ortho-hydroxycinnamic 



CO 



acid. It has the constitution C (! H 4 / 



\CH---CH. 

 This substance occurs in woodruff, hawthorn, and other plants. 



2. (ii.) Essential Oils containing Sulphur. 



Oil of mustard allyl isothiocyanate, C H H 5 .N:C:S. 

 Oil of garlic allyl sulphide, (C 3 H 5 ) 2 S. 

 The latter is present in onions, leeks, cress, radishes, &c. 



Many of the substances belonging to the last two classes are 

 not present as such in the plant, but in union with glucose 

 and other substances as the compounds known as gluco- 

 sides ; e.g., almonds do not contain any benzaldehyde but 

 amygdaline, CgoH^NOu, which in presence of water and under 



Ann. 316, 196 ; Jour. Chem. Hoc. 1901, abst. i. 477. 



