208 poisons : THEIR effects and detection. [§§ 259, 260. 
and S. japonica ; 1 together with the roots of the bitter and sweet 
Cassava. 
In only a few of these, however, has the exact amount of either 
prussic acid or amygdalin been determined ; 1 grm. of bitter almond 
pulp is about equal to 2| mgrms. of anhydrous prussic acid. The 
kernels from the stones of the cherry, according to Geiseler, yield 3 
per cent, of amygdalin ; therefore, 1 grm. equals 0-177 grm. of HCN. 
§ 259. The wild service-tree (Prunus padus) and the cherry-laurel 
(Prunus laurocerasus ) contain, not amygdalin, but a compound of 
amygdalin with amygdalic acid ; to this has been given the name of 
laurocerasin. It was formerly known as amorphous amygdalin ; its 
formula is C 40 H 55 NO 24 ; 933 parts are equivalent to 27 of hydric cyanide 
— that is, 100 parts equal to 2-89. 
In the bark of the service-tree Lehmann found *7 per cent, of 
laurocerasin ( = -02 HCN), and in the leaves of the cherry-laurel 1-38 
per cent. ( = -039 HCN). 
Francis, 2 in a research on the prussic acid in cassava root, gives as 
the mean in the sweet cassava -0168 per cent., in the bitter -0275 per 
cent., the maximum in each being respectively -0238 per cent, and 
•0442 per cent. The bitter-fresh cassava root has long been known as 
a very dangerous poison ; but the sweet has hitherto been considered 
harmless, although it is evident that it also contains a considerable 
quantity of prussic acid. 
The kernels of the peach contain about 2-85 per cent, amygdalin 
( = •17 HCN); those of the plum -96 per cent. ( = -057 HCN); and 
apple pips -6 per cent. ( = -04 per cent. HCN). A. Hebert 3 has 
found a few milligrammes of HCN in 100 grammes of the young shoots 
of Ribes rubrum ; 0-04 per cent, in the embryo of the fruit of Eriobotrya 
japonica, and from 0 - 01 per cent, to 0-001 per cent, in various parts of 
Aquilegia vulgaris at the commencement of vegetation. 
It is of great practical value to know, even approximately, the 
quantity of prussic acid contained in various fruits, since it has been 
adopted as a defence in criminal cases that the deceased was poisoned 
by prussic acid developed in substances eaten. 
§ 260. Statistics. — Poisoning by the cyanides (prussic acid or cyanide 
of potassium) occupies the sixth place among poisons in order of 
frequency in this country, and accounts for more than 40 deaths 
annually. 
In the five years ending 1916 there were recorded no less than 268 
cases of accidental, suicidal, or homicidal poisoning by prussic acid and 
1 The bark and green parts of the Prunus avium, L., Prunus mahaleb, L., and 
herbaceous Spircece yield no prussic acid. 
2 “ On Prussic Acid from Cassava,” Analyst, April 1877, p. 5. 
3 Bull. Soc. Chim., iii. 19, 1898. 
