38 THE PRODUCTION OF VOLATILE OILS AXD PERFUMERY PLAXTS. 



t illation are for all practical uses identical. Mention has been made 

 previously of the fact that the oil in these plants is formed by re- 

 action and does not preexist in the tissues. The glucosid gaultherin 

 is the constituent which is responsible for the formation of this oil, 

 and since the reaction between this glucosid and the plant ferment is 

 the same in both plants, the resulting volatile oil (or methyl salicy- 

 late) must necessarily be similar. 



In the case of the sweet birch, which is a tree of some size, the bark 

 of the trunk and the small branches are used for distillation, being 

 previously cut into small pieces and allowed to macerate with water 

 before introduction into the still. A yield of three-tenths to three- 

 fifths of 1 per cent of oil is obtained. On the other hand, for 

 the separation of the oil of wintergreen the leaves and twigs are 

 used, the plant being more or less shrubby. The same treatment is 

 applied to wintergreen as to sweet birch, maceration in water being 

 allowed to continue for a period of several hours prior to distillation. 

 The yield of volatile oil from wintergreen varies from one-half to 1 

 per cent. Owing to the abundance of these plants their cultivation 

 especially for the volatile oil has not been attempted, the material 

 being collected from the plants as they grow in their native habitats. 

 The strict enforcement of the Food and Drugs Act has tended to 

 curtail largelv the use of the svnthetic oil (methvl salicvlate) for 

 certain purposes where the natural oil is required. A more active 

 demand for the natural oils of sweet birch and wintergreen has neces- 

 sarily resulted, the j^rice of these oils being thereby materially 

 advanced. 



CANADA FLEABASE. 



Several other plants capable of yielding volatile oils of some value 

 are at present distilled in the United States. A very common herb 

 growing abundantly in the Xorth-Central and "Western States, the 

 Canada fleabane {Erigeron canadensis)^ usually regarded as a weed 

 and known to westerners as the fireweed (not the true fireweed, how- 

 ever), is distilled in a small way in connection with the distillation 

 of peppermint. The plant, which is a hard}' annual, is not cultivated, 

 but is cut in the wild condition, no special care being taken to elimi- 

 nate other aromatic weeds or plants, and consequently there results 

 an oil which, although representing the oil of erigeron, is far below 

 the true standard of the oil, owing to the presence of extraneous plant 

 matter introduced during distillation. 



EVCALYPTUS. 



The production of eucalyptus oil from the leaves and twigs of the 

 blue-ginn tree (EycaJyptus glohuJus) is of considerable importance 

 in the volatile-oil industry of the United States. The commercial 



105 



