407 
ON CYANOGENESIS IN PLANTS. 
dhurrinic acid is so small that sufficient material for analysis and identification could 
not be obtained. A small quantity of the acid was converted into silver salt, and a 
weighed quantity of the latter ignited, with the following result :— 
•1058 gramme gave ‘0399 Ag = 38'65 per cent., C s H 7 0 4 Ag requires 39‘05 per cent. 
It seemed highly probable that the alkaline hydrolysis of dhurrin with the 
formation of dhurrinic acid, and the decomposition of the latter by dilute acids, might 
be strictly comparable with the similar reactions of amygdalin, which, when hydro¬ 
lysed by alkalis, furnishes amygdalic acid, this acid by heating with dilute acids 
being hydrolysed into mandelic acid and dextrose. 
Amygdalin. 
C'2 0 H 27 NO 1] 
Amygdalic acid and 
ammonia. 
c 30 h 28 o 13 + nh 3 
Mandelic acid + 2 mols. 
dextrose. 
C 8 H 8 0 3 2C 6 H 12 0 6 . 
Dhurrin. 
c 14 h 17 o 7 n 
Dhurrinic acid and 
ammonia. 
c 14 h 18 0 9 + nh 3 
Parahydroxymandelic acid 
+ 1 mol. dextrose. 
c 8 ha + c 6 h 12 0 6 . 
On this analogy the crystalline hydrolytic product of dhurrinic acid would be 
parahydroxymandelic acid. We have established the identity of the two substances 
by comparing the hydrolytic product with parahydroxymandelic acid prepared by 
the hydrolysis of the cyanhydrin of parahydroxybenzaldehyde. 
As parahydroxymandelic acid is now prepared for the first time, the following 
outline of the process employed may be given. 
Preparation of Parahydroxymandelic Acid .—Ten grammes of parahydroxy¬ 
benzaldehyde were dissolved in 50 cub. centims. of boiling water, and 30 grammes of 
potassium cyanide added to the solution, which was then cooled in a freezing mixture 
and 50 cub. centims. of strong hydrochloric acid gradually added, the whole being- 
set aside for about 12 hours. The mixture was extracted with ether, the latter 
being allowed to spontaneously evaporate, leaving an oily residue, which was mixed 
with 20 cub. centims. of strong hydrochloric acid and sufficient alcohol to keep it in 
solution. This mixture was boiled for 3 hours, neutralized with sodium carbonate, 
filtered from the large quantity of resin formed, and extracted with ether in order 
to remove unaltered aldehyde. The residual liquid was then made acid with dilute 
sulphuric acid and extracted with ether until exhausted. The solvent was then 
distilled off, the oily residue boiled with water, to which a little animal charcoal had 
been added, and the filtered solution evaporated in a vacuum. After several days 
rosettes of needles appeared in the oily residue, and these after recrystallisation from 
alcohol melted at 180°, and further resembled the acid obtained from dhurrin in 
giving a brown coloration with ferric chloride, and a crystalline bromine derivative 
melting at 185°. 
The yield of parahydroxymandelic acid furnished by the process described above is 
