BITTER ALMONDS 163 



BITTER ALMONDS 



(Amygdala Amara) 



Source, &c. The bitter almond tree (Prunus Amygdalus, Stokes, 

 var. amara, Baillon) is indistinguishable from the sweet by any per- 

 manent botanical character, and enjoys the same geographical dis- 

 tribution, although it is not cultivated to so large an extent. It 

 is remarkable, therefore, that the seeds should invariably contain 

 a constituent amygdalin that is never present in the seed of the 

 sweet almond tree. The poisonous properties of the water distilled 

 from the bitter almond (and the cherry-laurel leaf), due to the pre- 

 sence and decomposition of a cyanogenetic glucoside, have long 

 been known ; it was the discovery of hydrocyanic acid in it that led 

 to the recognition of the poisonous nature of this acid, which, curiously 

 enough, had up to then (1802) escaped observation. 



Bitter almonds are imported chiefly from northern Africa, from 

 Sicily, and from the south of France. 



Description. In form and appearance bitter almonds closely 

 resemble Valencia almonds, but they are usually smaller and less 

 regular. They have, however, a bitter taste, and yield with water 

 an emulsion easily distinguished from that of the sweet almond by 

 its characteristic odour. 



Constituents. Bitter almonds resemble the sweet in containing 

 both a bland fixed oil and proteids, the former of which is obtained 

 by crushing the almonds between horizontal grooved rollers and 

 pressing in powerful hydraulic presses. But they differ essentially 

 from the sweet in containing a colourless, crystalline glucoside, amyg- 

 dalin (2'5 to 4 per cent.), which is not present in the sweet. This 

 substance is left in the cake obtained after the oil has been expressed, 

 and can be extracted from it by digestion with alcohol. It has a 

 bitter taste and is odourless, but when an aqueous solution is mixed 

 with an emulsion of sweet almonds the amygdalin is decomposed 

 with production of benzaldehyde, hydrocyanic acid and dextrose. 



C 20 H 27 NO n + 2H 2 = 2C 6 H 12 6 + C 6 H 5 COH + HCN 



Amygdalin Dextrose Benzaldehyde Hydrocyanic acid 



This change is effected by the emulsin contained in the sweet 

 almond. Emulsin is also contained in the bitter almond itself, but, 

 being localised in particular cells of the seed, is unable to act upon 

 the amygdalin until the seeds are crushed and water added. When 

 therefore bitter almonds (or cake) are crushed and mixed with water, 

 the characteristic odours of benzaldehyde and hydrocyanic acid 

 are developed. If, after standing a few hours, the mixture is sub- 

 jected to distillation, an oily liquid of strong bitter almond odour 



