164 SEEDS 



is obtained, together with a quantity of watery distillate ; the oil 

 is volatile or ^essential oil of bitter almonds, and consists of benzal- 

 dehyde and hydrocyanic acid, partly in the free state and partly 

 combined as benzaldehyde-cyanhydrin. It can be freed from hydro- 

 cyanic acid by shaking it with milk of lime ; all the hydrocyanic 

 acid, both free and combined, forms calcium cyanide. The addition 

 of ferrous sulphate then converts the cyanide into calcium ferro- 

 cyanide, and the oil can be obtained free from hydrocyanic acid 

 by redistilling in a current of steam. No benzaldehyde or hydro- 

 cyanic acid is developed by the sweet almond, because it contains 

 no amygdalin. 



Bitter almonds yield from O5 to 0'8 per cent, of volatile oil and 

 about 0'25 per cent, of hydrocyanic acid. 



Many other Rosaceous plants contain amygdalin, such as the 

 peach, apricot, plum, &c., not only in the seed, but also in the young 

 shoots and flower-buds. 



Amygdalin is closely allied to, but not identical with, prulaurasin, and is 

 also distinct from a similar glucoside that occurs in the bark of Prunus serotina, 

 Ehrhart (compare also p. 252). Its hydrolysis is said to occur in three stages, 

 each effected by a particular enzyme contained in the emulsin. 



Benzaldehyde is also prepared from benzyl chloride, C 6 H 6 .CH 2 C1, or benzal 

 chloride, C 6 H 5 .CHC1 2 , and sold as oil of bitter almonds ; it has a less pleasant 

 odour than that obtained from bitter almonds. 



Uses. Bitter almonds are sedative, but as the poisonous hydro- 

 cyanic acid yielded by them varies in quantity they are unreliable. 

 They are also employed for flavouring, but they should for a similar 

 reason be used with caution. 



Substitutes. Apricot kernels contain constituents similar to those 

 of the bitter almond. They are imported in large quantities from 

 Syria and California and are often used by confectioners in the 

 place of bitter almonds. The fixed oil expressed from them is com- 

 monly sold as ' Oleum Amygdalae Persicum ' or ' peach kernel oil.' 

 From the cake an essential oil (0*6 to 1*0 per cent.) is distilled as 

 from bitter almond cake. 



MELON PUMPKIN SEEDS 

 (Cucurbitae Semina Praeparata) 



Source, &c. Melon pumpkin seeds are obtained from Cucurbita 

 maxima, Duch. (N.O. Cucurbilacece) , a native of the Levant but 

 cultivated on the shores of the Mediterranean. For use in medicine 

 they should not be more than one month old and should be deprived 

 of their seed-coats. 



