730 



Phaseolus Lunatus Beans. 



[march, 



latter thoroughly washed. In this process the glucoside is 

 brought into contact with the ferment and completely decom- 

 posed, the prussic acid formed being washed away by the 

 water, so that it can be understood readily enough that meal 

 so prepared is innocuous. Large quantities of cassava are also 

 used as a vegetable, being boiled or baked in the same manner 

 as potatoes. Treatment of this kind will destroy the activity 

 of the ferment, but will not necessarily affect the glucoside, 

 so that boiled or baked cassava is in much the same position as 

 hot-pressed linseed cake, i.e., it contains a glucoside capable of 

 yielding prussic acid, but is harmless so long as it is not in 

 contact with a ferment capable of decomposing the glucoside. 



Numerous cases of poisoning by cassava are on record, but 

 these seem to have been caused invariably by the consumption 

 of raw cassava. It would seem, therefore, that in the cases of 

 linseed and cassava, the application of enough heat to destroy 

 the activity of the enzyme present renders these materials 

 harmless, and the question arises as to whether similar treat- 

 ment would not be efficacious in the case of Rangoon beans. 



The statement has been made by exporters of Java beans 

 that the latter become safe to use after being boiled in water,, 

 and Messrs. Tatlock and Thomson have stated (loc. cit.) that 

 when Java beans are steeped in water and afterwards boiled, a 

 considerable proportion of the prussic acid-yielding glucoside 

 is removed. Experiments made at the Imperial Institute with 

 Java beans have shown, however, that practically no change 

 in the quantity of glucoside present is effected by this means, 

 but as the activity of the enzyme is destroyed, the ground 

 boiled beans no longer liberate prussic acid when mixed with 

 water. 



There is on record one case which seems to indicate that , this 

 treatment of Java beans is insufficient as a precaution against 

 poisoning. Thus Robertson and Wynne state (Zeit. AnaL 

 Chim., 1905, XLIV, 735) that four persons out of seven who had 

 made a meal of cooked " Kratok " beans (Kratok is a vernacular 

 name for Java beans in use in Holland and Germany), died,, 

 and in each case clear proof of poisoning by prussic acid was 

 obtained. 



In view of the large interests concerned in the trade in Rangoon 

 beans, and as, apart from the prussic acid they yield, they appear 



