AROMA OF PLANTS, 15 



represents the volatile oil of winterj!;reen. In order to effect this 

 In^drolysis of the gliicosid in AA'interoreen or sweet birch, the material 

 is simply macerated with water. A reaction innnediately begins, 

 assisted by the plant ferments, which act as catalysing- agents, with 

 the formation of the volatile methyl salicylate and glucose, as 

 follows : 



CuHisOg , „ ^ C6H,(OH)COOCH3 , CeHiA, 



;+ ap- 



gaultherin"' - methyl salicylate ~ glucose" 



If after the reaction is complete the fermented material is put into 

 a distilling apparatus, the volatile oil of wintergreen and sweet birch 

 may be distilled as a colorless oil with the characteristic wintergreen 

 odor so commonly known. 



In addition to the two plants mentioned containing glucosidal sub- 

 stances which split up into a volatile oil and a sugar, the ordinary 

 bitter almonds and peach, apricot, and prune kernels may be men- 

 tioned. These kernels contain the glucosid amygdalin, which when 

 hydrolyzed yields benzaldehyde, hydrocyanic acid, and glucose, as 

 follows : 



C20H27NO,, HON CeH,CHO CeHiA 



amygdalin ■" - hydro- benzalde-"' glucose' 



cyanic hyde 

 acid 



Therefore, when the ground kernels are macerated or hydrolyzed in 

 the presence of water and then distilled, the ordinary volatile oil char- 

 acteristic of bitter almonds and of peach, prune, and apricot kernels, 

 is obtained. 



These kernel oils are in every way identical, just as the oils of win- 

 tergreen and sweet birch are practical^ identical, the former con- 

 sisting chiefly of hydrocyanic acid and benzaldehyde and the two 

 latter of nearly pure meth}^ salicylate. 



One other example of an oil produced by fermentation is the oil 

 of mustard seeds. These seeds contain the glucosid sinigrin, which 

 likewise suffers hydrolysis when ground seeds are macerated in 

 water, producing the volatile oil of mustard (alhd iso-sulphocyanid), 

 glucose, and potassium acid sulphate, according to the following 

 reaction : 



C,oH,6NS,KO, C3H,CSN CeHiA , KHSO^ 



sinigrin ' - allyl iso- glucose ' potas- 

 sulpho- slum 



cyanid acid 



sulphate 



The fermented mixture readily yields the volatile oil by distilla- 

 tion with steam. The medicinal action attributed to mustard seeds 

 is due to the mustard oil developed in the reaction mentioned. This 



195 



