June 1908.J 



533 



Edible Products. 



Samples Received prom the Board 

 of Agriculture. 



Prussic Acid. 



'* Large white haricots " ob- 

 tained in Glasgow ... Nil. 



" Small white haricots," 

 said to be of Hungarian 

 origin ... •■• Nil. 



Samples obtained from Firms 

 in London. 



Prussic Acid. 



Firm A.—" Butter beans," 



large white ... Traces 

 " Dark red haricots " Nil. 

 Firm B. — Danubian beans Nil. 



Samples obtained in Paris. 



Prussic Acid. 

 Haricots d' Alger, blanc a rames Nil. 

 Haricots d' Alger, noir a rames Nil. 



It is of interest to note that the 

 "Butter beans'" now largely sold for 

 human food in this country furnish 

 traces of prussic acid, but the other 

 " haricot" beans included in this group, 

 which are probably mainly, if not 

 wholly, derived from Phaseolus vulgaris, 

 yield none. 



It will be seen on comparing the 

 results quoted in these two sets of tables 

 that all the earlier analyses indicate the 

 production by white Burma beans of no 

 prussic acid or only traces ; fairly large 

 quantities (0.016 to 0.026) per cent, have 

 so far as is known only been recorded 

 for consignments of white Burma beans 

 imported during 1907, Even these quan- 

 tities are, however, only about one-fifth 

 of those yielded by some specimens of 

 Java beans, which were coloured. 



No explanation of this unfavourable 

 change in the quality of white Burma 

 beans can be given at present. 



It has been suggested recently by the 

 French Consul at Rangoon that consign- 

 ments of Rangoon beans may contain 

 small quantities of the poisonous beans 

 of Psophocarpus tetragonolobus, and 

 that their production of prussic acid 

 may be due to such inclusions. The 

 only extraneous beans noticed in sam- 

 ples, both of Rangoon and Java beans 

 examined at the Imperial Institute, have 

 been those of Dolichos lablab, which Dr. 

 Leather has shown also yield small 

 quantities of prussic acid. None of the 

 investigators who have worked on Ran- 

 goon beans have recorded the occurrence 

 among them of Psophocarpus tetragono- 

 toous beans, so that there is no evidence 

 to support the Consul's suggestion, 

 whilst ihere is plenty of evidence that 

 the Rangoon beans themselves actually 

 yield prussic acid. 



Although both red and white Burma 

 beans have been imported in large quan- 

 tities into the United Kingdom, and 

 used for feeding cattle during the last 

 few years, no cases of poisoning have so 

 far been traced to them, but it is obvious 

 that if the amount of prussic acid 

 furnished by different consignments of 

 these beans may vary over as wide a 

 range as is shown by the figures quoted 

 above, the use of these beans for feed- 

 ing cattle may be attended with some 

 danger. 



There is nothing on record to show 

 what ill-effects — if any— are produced 

 by the long-continued use of feeding 

 materials capable of producing small 

 quantities of prussic acid, but the 

 following facts are of some interest in 

 this connection. It was shown by 

 Jorissen and Hairs as long ago as 1888 

 that ground linseed when placed in con- 

 tact with water yields prussic acid, and 

 these authors found that this was due 

 to the interaction of a glucoside and 

 ferment. Recently, in conjunction with 

 Dr. Auld, we have re-examined the 

 glucoside and ferment of linseed and 

 fouud that they are identical with the 

 cyanogenetic glucoside and ferment of 

 the beans of Phaseolus lunatus. (Proc. 

 Roy, Soc, 1«08, B. LXXVIII, 152). Since 

 in the mere expression of oil from lin- 

 seed the glucoside is not destroyed, it 

 became of interest to ascertain how 

 much of prussic acid is furnished by the 

 linseed cake commonly used as a feed- 

 ing stuff for cattle in this country. 

 Samples of linsaed cake were therefore 

 obtained from two of the principal 

 makers of this product in the United 

 Kingdom. The samples of cake were 

 both of the highest quality, and the 

 linseed from which they were made was 

 guaranteed by the firms to contain a 

 minimum of 98 per cent of true linseed. 

 The amount of prussic acid yielded by 

 the two samples was estimated and 

 found to be as follows :— 



Prussic Acidj 

 Per cent, 



Sample No. 1 035 



No. 2 0-041 

 These quantities it will be seen are about 

 50 per cent, greater than those obtained 

 from any of the samples of Burma beans 

 examined. Although cases of the poison- 

 ing of cattle by green stems of linseed 

 have been recorded in India, there are s 

 so far as is known, no cases of poisoning 

 of cattle by linseed cake ou record in 

 this country. 



There is, however, one important 

 difference betweeu the "availablity *' of 

 prussic acid iu the beans of Phaseolus 

 lumtus and in the linseed cake of com* 



