Page:On the Continuity of Effect of Light and Electric Radiation on Matter.djvu/1

154 Dhurrin crystallises well, and is soluble in both water and alcohol. When hydrolysed by emulsin or by dilute acids it is converted into parahydroxybenzaldehyde, dextrose, and hydrocyanic acid according to the equation C$14$H$17$O$7$N + H$2$O = C$7$H$6$O$2$ + C$6$H$12$O$6$ + HCN. When warmed with alkalis, dhurrin is resolved first into dhurrinic acid and ammonia. This acid subsequently undergoes further hydrolysis when warmed with dilute hydrochloric acid, being converted into parahydroxymandelic acid and dextrose (1) C$14$H$17$O$7$N + H$2$O = C$14$H$18$O$9$ + NH$3$, (2) C$14$H$13$O$9$ + H$2$O = C$8$H$8$O$4$ + C$6$H$12$O$6$.

The identity of the parahydroxymandelic acid was established by its synthesis from the cyanhydrin of parahydroxybenzaldehyde.

Dhurrin differs from the other two known cyanogenetic glucosides, the amygdalin of bitter almonds and the lotusin found by the authors in Lotus arabicus, in being derived from dextrose and not from maltose.

The authors point out the protective purpose served by the existence of the cyanogenetic glucoside in the young plant.

The authors intend to fully investigate the several problems which are raised by the occurrence of cyanogenetic glucosides in plants.

They are at present engaged in examining several other plants which have furnished prussic acid, among them being Manihot utilissima, Linum usitatissimum, Lotus australis, and Phaseolus lunatus.

 

Introduction.

Though the theory of coherence gives a simple explanation of many cases of diminution of resistance in a mass of metallic particles under electric radiation, yet there are other cases which are not explicable by that theory. If coherence be due to electric welding, it would follow that all sensitive particles would exhibit a permanent diminution of resistance; in other words, the action should be non-discriminative and there should be no self-recovery. In my previous paper, however, I have shown that the effect of radiation is by no means non-discriminative. To the contrary, while its effect on the positive class of substances, e.g., Mg.Fe.Ni, is a diminution of resistance, it acts on the negative class, e.g., K.Ag′.Br.I, in a precisely opposite way, that is to say, it produces in these an increase of resistance. Further, the 