1 equivalent of amygdalin--_i.e._, 457 parts--yielding 1 equivalent of CNH or 27 parts; in other words, 100 parts of amygdalin yield theoretically 5·909 parts of prussic acid,[236] so that, the amount of either being known, the other can be calculated from it. [236] According to Liebig and Wöhler, 17 grms. of amygdalin yield 1 of prussic acid (_i.e._, 5·7 per cent.) and 8 of oil of bitter almonds. Thirty-four parts of amygdalin, mixed with 66 of emulsin of almonds, give a fluid equalling the strength of acid of most pharmacopœias, viz., 2 per cent. Greshoff[237] has discovered an amygdalin-like glucoside in the two tropical trees _Pygeum parriflorum_ and _P. latifolium_. The same author states that the leaves of _Gymnema latifolium_, one of the Asclepiads, yields to distillation benzaldehyde hydrocyanide. Both _Lasia_ and _Cyrtosperma_, plants belonging to the natural family of the Orontads, contain in their flowers potassic cyanide. _Pangium edule_, according to Greshoff, contains so much potassic cyanide that he was able to prepare a considerable quantity of that salt from one sample of the plant. An Indian plant (_Hydnocarpus inebrians_) also contains a cyanide, and has been used for the purpose of destroying fish. Among the Tiliads, Greshoff found that _Echinocarpus Sigun_ yielded hydrocyanic acid on distillation. Even the common linseed contains a glucoside which breaks up into sugar, prussic acid, and a ketone. [237] M. Greshoff--_Erster Bericht über die Untersuchung von Pflanzenstoffen Niederländisch-Indiens. Mittheilungen aus dem chemisch-pharmakologischen Laboratorium des botan. Gartens des Staates_, vii., Batavia, 1890, Niederländisch. Dr. Greshoff’s research indicates that there are several other cyanide-yielding plants than those mentioned in the text. The following plants, with many others, all yield, by appropriate treatment, more or less prussic acid:--Bitter almonds (_Amygdalus communis_); the _Amygdalus persica_; the cherry laurel (_Prunus laurocerasus_); the kernels of the plum (_Prunus domestica_); the bark, leaves, flowers, and fruit of the wild service-tree (_Prunus padus_); the kernels of the common cherry and the apple; the leaves of the _Prunus capricida_; the bark of the _Pr. virginiana_; the flowers and kernels of the _Pr. spinosa_; the leaves of the _Cerasus acida_; the bark and almost all parts of the _Sorbus aucuparia_, _S. hybrida_, and _S. torminalis_; the young twigs of the _Cratægus oxyacantha_; the leaves and partly also the flowers of the shrubby _Spiræaceæ_, such as _Spiræa aruncus_, _S. sorbifolia_, and _S. japonica_;[238] together with the roots of the bitter and sweet _Cassava_. [238] The bark and green parts of the _Prunus avium_, L., _Prunus mahaleb_, L., and herbaceous _Spirææ_ yield no prussic acid.