ON THE OCCURRENCE OF PRUSSIC ACID 

 AND ITS DERIVATIVES IN PLANTS 



By T. A. HENRY, D.Sc. (Lond.) 



Principal Assistant, Scientific and Technical Department, Imperial Institute 



Though the poisonous character of bitter almonds appears to 

 have been well known in early times, and they were regularly 

 prescribed by physicians in the Middle Ages, it was not till 1800 

 that Bohm, 1 a pharmacist of Berlin, detected prussic acid in the 

 volatile oil produced when crushed bitter almonds are macerated 

 in cold water and the liquor obtained, subsequently distilled. 

 Curiously enough, Scheele, 2 who discovered prussic acid in 

 1782, did not realise that it was poisonous, and the final proof 

 that prussic acid was the toxic constituent in volatile oil of 

 bitter almonds was made by Schrader in 1803. 3 



Since that time the occurrence of free prussic acid, or of 

 derivatives which readily yield this acid, 4 has been noted in 

 a large number of plants belonging to such different natural 

 orders as the Gramineae, Liliaceae, Salicaceae, Ranunculaceae, 

 Passifloreae, Bixineae, Tiliaceae, Sterculiaceae, Linacese, Sapin- 

 daceae, Rhamnaceae, Celastrineae, Euphorbiaceae, Saxifragaceae, 

 Rosaceae, Leguminosae, Sapotaceae, Oleaceae, Asclepiadaceae, 

 Convolvulaceas, Rubiaceae, and Compositae. In an incom- 

 plete list of plants known to contain cyanogenetic compounds, 

 published by Jouck in 1902, 5 over one hundred species are 

 enumerated, and this number has been increased since. 



Most of these cases are only of importance at present as 

 pointing to the fact that the occurrence of cyanogenetic com- 

 pounds in plants is far more common than is generally believed; 



1 Neiees allgemeines Journal der Chemie, 1803. 



2 Nova acta Acad. reg. sued., 1782. 



3 Trommsdorfs Journal, 1803. 



4 Dunstan and Henry have used the term " cyanogenesis " to describe this 

 process, and the adjective " cyanogenetic " to describe the precursors, usually 

 glucosides, of prussic acid in the plant. 



5 Jouck, Beitrdge zur Kenntnis der Blausdure abspaltenden Glycoside, Strass- 

 burg, 1902. 



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