408 
PROFESSOR WYNDHAM R. DUNSTAN AND DR. THOMAS A. HENRY 
only about 1 per cent., as this acid is readily converted by hydrochloric acid into a resin 
dissolving in alcohol with a fine purple colour. The cyanhydrin of parahydroxy- 
benzaldehyde is also very unstable, being easily hydrolysed by water into prussic 
acid and the aldehyde, so that in each experiment about 50 per cent, of the latter is 
regenerated. Attempts were made to utilise anisaldehyde cyanhydrin for the 
preparation of the acid, but although this substance is somewhat more stable than its 
lower homologue, a considerable loss occurs in decomposing the methoxy-mandelic acid 
first formed. 
A small quantity of the silver salt prepared from the acid obtained as described 
above gave the following results on analysis :—- 
•1286 gramme gave ’1642 gramme C0 2 , C 34‘83 per cent. 
•0308 „ HoO, H 2-67 
‘1286 gramme gave a residue of silver weighing '0506 gramme = 39’35 per cent. 
C 8 H 7 0 4 Ag requires C 34’9, H 2‘48, Ag 39'09 per cent. 
The properties and reactions of dhurrin, as described in the foregoing paragraphs, 
may for convenience be summarised as follows : — 
(1) The glucoside is hydrolysed by emulsin and dilute acids into parahydroxy- 
benzaldehyde, hydrocyanic acid, and dextrose. 
(2) It is decomposed hydrolytically by alkalis into dhurrinic acid and ammonia. 
(3) Dhurrinic acid is hydrolysed by dilute acids into parahydroxymandelic acid 
and dextrose. 
These reactions we believe are fully accounted for by assigning to dhurrin the 
constitution of a dextrose ether of the cyanhydrin of parahydroxybenzaldehyde, 
which may be represented by the formula given below 
HO 
CuHnOj 
CH.O.CoHnOo 
H HO 
CN 
Dhurrin 
Hydrolysis by acids and emulsin Hydrolysis by alkalis 
(prussic acid, dextrose, parakydroxy- (dhurrinic acid and ammonia), 
benzaldehyde). 
Dhurrin is therefore the parahydroxy-derivative of the glucoside of mandelic 
nitrile which was prepared by Fischer by the partial hydrolysis of amygdalin 
with invertase, and resembles this glucoside in the ease with which it undergoes 
