191 1.] Hydrocyanic Acid from Linseed Cake. 905 



authors (Jour. Board of Agric, Man, 1908, 729) quote two 

 commercial cakes which gave total hydrocyanic acid 0*035 

 and 0*041 per cent, respectively. But they clearly emphasise 

 the important question of " availability " of the poison, show- 

 ing that no acid is formed on maceration with cold water, 

 the enzyme having been, presumably, destroyed by the heat- 

 ing during process of manufacture. With such cake there 

 can hardly be any question of poisoning, since there is no 

 evidence to show that the glucoside is poisonous, or that it 

 is resolved by digestive ferments or those contained in other 

 foods. 



Cakes are, however, often met with which yield "avail- 

 able " hydrocyanic acid, by which it is to be clearly under- 

 stood that maceration with cold water produces free hydro- 

 cyanic acid. In such instances it is probable that part of 

 the original enzyme has escaped destruction by heat. It has 

 been found that fermentation goes on in 1 per cent, hydro- 

 chloric acid and also in 1 per cent, sodium bicarbonate 

 solutions, and would not therefore be inhibited by the body 

 fluids. The development of acid is, moreover, complete on 

 twelve hours' digestion in water at 12 0 C. None of the cakes 

 examined here contained more than 0*025 per cent, of available 

 acid. Dr. Voelcker has kindly informed me of several cakes 

 examined by him of which the lowest gave 0*0046 per cent, 

 or 0*321 grains per pound, the highest 0*051 per cent, or 

 3*57 grains per pound. My own specimens averaged 0*025 

 per cent. Dr. Voelcker's 0*051 per cent, sample was a 

 Calcutta cake, and he was informed that sheep refused it, 

 unless kept without other food.* 



The maximum noted by Dunstan and Henry (loc. tit.) 

 for Java beans is 0*123 per cent., and it might therefore, 

 bearing in mind the fairly rapid evolution of acid, be anti- 

 cipated that linseed cakes, especially such as the one noted 

 by Dr. Voelcker, might prove injurious, possibly even fatal. 

 Taking cake of 0*025 per cent, hydrocyanic acid, a daily 

 ration of 1 lb. for a sheep means a daily dose of 1*75 grains 

 of acid, slowly evolved during digestion. A 2-lb. ration for 

 a heifer would represent 3*5 grains of acid per diem. The 

 medicinal doses are for the sheep J, for horse or ox £ grain. 



By the courtesy of Col. Duncombe and Mr. E. G. Haskell,. 



* See also Jonrn. R.A.S.E., 1909, p. 342. 



