PERFUMES AND ESSENTIAL OILS 355 



Chinese camphor to distinguish it from Borneo camphor which 

 is obtained from Borneo and Sumatra. The former is obtained 

 from the Laurus camphora, the latter from Dryobalanops cam- 

 phora, both large trees. Their chemical relations are indicated 

 by the following formulae : 



Chinese Camphor. Borneo Camphor. 



or or 



/CO /.CH-OH 



ri TT / n TT / 



^8- tl 14\ t-'S-tt-^Xj 



CJti 2 C Ji 2 



Camphor has always been procured by the crude and wasteful 

 method of cutting up the wood, in which the camphor exists in 

 crystals, and distilling it with water in stills of very primitive 

 construction. 



It is purified by resublimation and is obtained in large hemi- 

 spherical masses called bells, or being obtained in crystalline 

 powder is then compressed into cakes. Common camphor is a 

 natural constituent of several essential oils, especially those of 

 lavender, rosemary, and sage. Borneo camphor does not come 

 into European commerce, but it is preferred in Eastern Asia, 

 where it commands a high price, and is used chiefly for making 

 incense and generally for ceremonial purposes. 



These two substances camphor and borneol are easily con- 

 verted the one into the other, having between them a difference 

 of only two atoms of hydrogen and standing toward each other 

 in the relation of ketone (camphor) and secondary alcohol 

 (borneol). Hence camphor is easily made from borneol by the 

 action of oxidising agents, nitric acid, for example, while borneol 

 can be produced from camphor by the action of sodium on an 

 alcoholic solution of camphor. 



Camphor has been the subject of very protracted investiga- 

 tions, as its constitution was for many years somewhat mysterious. 

 These difficulties have now been cleared away, and the know- 

 ledge now existing of the relation of camphor to the terpenes has 

 enabled chemists to contrive a process by which it can be made 

 from oil of turpentine (pinene C 10 H 16 ). 



The artificial camphor is identical in every respect with 

 natural camphor, except that it is optically inactive while all the 

 natural products rotate the polarised ray. The manufacture of 



