408 STYRACE.E. 



By distilling the resin of benzoin with ten times its weight of zinc 

 dust, Ciamician (1878) chiefly obtained toluol, C''H5(CH='). 



Subjected to dry distillation, benzoin affords as chief product 

 Benzoic Acid, C^ffO^, together with empyreumatic products, among 

 which Berthelot has proved the presence (in Siam benzoin) of Styrol 

 (p, 274). The latter has been obtained in 1874 by Theegarten from 

 Sumatra benzoe by distilling it with water. When the resin is fused 

 with potash, it is partly decomposed and then, according to Hlasiwetz 

 and Barth (186G), yields among other products, protocatechuic acid 

 (more than 5 per cent.), C®H^(OH)^COOH, para-oxybenzoic acid, 

 C'H\OH)COOH, and pyrocatechin, C6H*(0H)-. 



Benzoic acid exists ready-formed in the drug to the extent of 14 to 

 18 per cent.^ Although the acid dissolves in 12 parts of boiling water, 

 the resin in which it is imbedded precludes its complete extraction by 

 this means. It is however easily accomplished by the aid of an alkali, 

 most advantageously by milk of lime, which does not combine with the 

 amorphous resins. 



Benzoin is not manifestly acted on by bisulphide of carbon, but if 

 kept in contact with it for a month or two, very large colourless crystals 

 of benzoic acid make their appearance. Brought into a warm room, the 

 crystals quickly dissolve, but are easily reproduced by exposure to cold. 



Most pharmacopoeias require not the inodorous acid obtained by a 

 wet process, but that afforded by sublimation, which contains a small 

 amount of fragrant empyreumatic products. The resin, when repeatedly 

 subjected to sublimation, affords as much as 14 per cent, of benzoic acid. 

 It has long been known that the opaque Avhite tears of benzoin are less 

 rich in benzoic acid than the transparent brown resin in which they lie. 

 From the latter, S. W. Brown (1883) extracted 13 per cent, of impure 

 acid, but from the former scarcely 8^ per cent. We are by no means sure 

 that such difference is constant. 



Bitter almond oil, which by oxidation yields benzoic acid, is wanting 

 in benzoin. Very little volatile oil is in fact to be got ; half a pound of 

 the best Penang benzoin yielded us by distillation with water only a 

 few drops of an extremely fragrant oil (styrol?). 



Ferric chloride imparts to an alcoholic solution of benzoin a dark 

 brownish green, which is not acquired under the same circumstances by 

 the aqueous decoction of the powdered resin. Benzoin dissolves in cold 

 oil of vitriol, forming a solution of splendid carmine hue, from which 

 water separates crystals of benzoic acid. 



Kolbe and Lautemann in 1860 discovered in Siam and Penang ben- 

 zoin together with benzoic acid, an acid of different constitution, which 

 in 1861 they recognized as Cinnamic Acid, C^H^O". Aschoff' (1861) 

 found in a sample of Sumatra benzoin, cinnamic acid only, of which he 

 got 11 per cent; and in amygdaloid Siam and Penang benzoin only 

 benzoic acid. In some samples of the latter, one of us (F.) has likewise 

 met with cinnamic acid. On triturating this sort with peroxide of lead 

 and boiling the mixture with water, the odour of bitter-almond oil, due 

 to the oxidation of cinnamic acid, is evolved. 



The simultaneous occurrence of benzoic and cinnamic acids, or the 



^ Lowe (1870) and Rump (1878) at- they have not shown with which substance 

 tempted to prove that the acid is partly it is combined in the drug, 

 present in the form of a compound, but 



