1906.] 



Cyanogenesis in Plants. 



149 



Isolation of the Glucoside. 



Flax plants (stems, leaves and roots) of about 4 or 5 inches in height were 

 thoroughly dried at a temperature not exceeding 40° C. The dried material 

 was ground to a fine powder and completely extracted with 90 per cent, 

 alcohol. The greater part of the solvent was then distilled off and the 

 residue poured into water, whereby chlorophyll, oily and resinous matters, 

 were precipitated. The aqueous liquid after decantation was decolorised by 

 the addition of a slight excess of lead acetate, and the filtrate, after treatment 

 with sulphuretted hydrogen, to remove the excess of lead, was evaporated 

 down to a low bulk under reduced pressure and set aside for a time. This 

 purified and decolorised extract was very rich in the cyanogenetic glucoside, 

 but it could not be induced to crystallise out of the syrupy mass. The 

 latter was, therefore, redissolved in alcohol and the solution poured into six 

 times its volume of ether. The sticky precipitate which separated consisted 

 principally of a mixture of dextrose and potassium nitrate. The solvent was 

 distilled from the decanted liquid and the dry residue again dissolved in 

 alcohol and the precipitation by means of excess of ether repeated. In this 

 case the precipitate was principally dextrose with a small quantity of the 

 glucoside. The solvent was again distilled from the decanted liquid and the 

 light brown syrupy residue set aside. After some days, masses of needles 

 arranged in rosettes began to separate and in a short time the whole of the 

 syrup had solidified, forming a crystalline mass. This was spread on a recently- 

 ignited porous tile and the fairly clean crystals, thus separated from the 

 viscous mother liquor, dissolved in alcohol and recrystallised until they were 

 colourless and of constant melting point. This material was carefully com- 

 pared with phaseolunatin prepared from the seeds of Phaseolus lunatus and 

 the two substances were proved to be identical. 



Determinations of the melting points of phaseolunatin and the flax 

 glucoside under the same conditions gave 138° C. (corr.) as the melting 

 point of each, and a mixture of the two substances also melted at this 

 temperature. 



The flax glucoside was found to have the specific rotation [«]d — 27°"4 

 in alcohol at 15°; that previously recorded for phaseolunatin is — 26° - 2 

 under the same conditions. 



Finally both substances crystallise in the same characteristic, spreading 

 rosettes of slender needles, and possess the same peculiar cool and bitter 

 taste. The total quantity of the glucoside obtained by us from flax did not 

 amount to more than 03 gramme, and as the results of the comparison of its 

 physical constants with those of phaseolunatin so positively established the 



