Among plants capable of emitting hydrocyanic acid, probably always accompanied with bitter almond oil, the tribes Pruneæ and Pomeæ of the rosaceous order may be particularly mentioned.
The farinaceous rootstocks of the Bitter Cassava, Manihot utilissima, Pohl, of the order Euphorbiaceæ, the source of tapioca in Brazil, have long been known to yield hydrocyanic acid.
A composite, Chardinia xeranthemoides Desf., growing in the Caspian regions, has been shown by W. Eichler also to emit hydrocyanic acid.[957] The same has been observed by the French in Gaboon[958] with regard to the fruits of Ximenia americana L. of the order Olacineæ, and the fact has been confirmed by Ernst of Caracas,[959] near which place the plant abounds. Mr. Prestoe of the Botanical Garden, Trinidad, informs us (1874) that in that island a convolvulaceous plant, Ipomœa dissecta Willd., contains a juice with a strong prussic acid odour. According to Lösecke, a common mushroom, Agaricus oreades Bolt., emits hydrocyanic acid.[960]
This acid is consequently widely diffused throughout the vegetable kingdom. Yet amygdalin has thus far only been isolated from a few plants belonging to the genus Prunus or its near allies.[961] In all other plants in which hydrocyanic acid has been met with, we know nothing as to its origin. Ritthausen and Kreusler (1871) have proved the absence of amygdalin in the seeds of a Vicia, which yield bitter almond oil and hydrocyanic acid. These chemists followed the process which in the case of bitter almonds easily affords amygdalin.
Commerce—[See preceding article].
Uses—Bitter almonds are used almost exclusively for the manufacture of Almond Oil, while from the residual cake is distilled Bitter Almond Oil. An emulsion of bitter almonds is sometimes prescribed as a lotion.
Adulteration—The adulteration of bitter almonds with sweet is a frequent source of loss and annoyance to the pressers of almond oil, whose profit largely depends on the amount of volatile oil they are able to extract from the residual cake.
FRUCTUS PRUNI.
Prunes; F. Pruneaux à médecine.
Botanical Origin—Prunus domestica L., var. ζ. Juliana DC.—It is from this tree, which is known as Prunier de St. Julien,[962] that the true Medicinal Prunes of English pharmacy are derived. The tree is largely cultivated in the valley of the Loire in France, especially about Bourgueil, a small town lying between Tours and Angers.