HYDROCYANIC ACID IN SUDAN GRASS' 



By C. O. vSwANSON ^ 

 Professor of Agricultural Chemistry, Kansas State Agricultural College 



In a previous paper ^ it was shown that hydrocyanic acid (HCN) is 

 obtained from green Sudan grass by macerating, digesting in water, and 

 distilling into a dilute solution of sodium or potassium hydroxid. Sev- 

 eral experiments reported in that paper made it clear that this acid does 

 not exist free in Sudan grass and is obtained only if the conditions of the 

 determination are favorable to enzym action. It appears to be a common 

 belief that hydrocyanic acid is developed by freezing. This merely bursts 

 the green cells and thus performs the same function as maceration, with 

 the result that the hydrocyanic acid is rapidly lost from frosted grass. 

 It was also shown that while in some cases poisoning had been reported 

 from pasturing Sudan grass, under normal conditions no poisoning took 

 place either before or after the grass was frozen. It was suggested that 

 when frozen the hydrocyanic acid had been liberated and then evap- 

 orated as the grass dried. 



Because of the importance of the subject it was thought worth while 

 to make further investigations. During the summer of 1920, material 

 was obtained from a i/20-acre plot of Sudan grass grown by the Depart- 

 ment of Agronomy of the Kansas State Agricultural College. The 

 Sudan grass had been planted early in June in rows about 2 feet apart. 

 On June 22, when the experiments were begun, the grass was about 6 

 inches high. These experiments were continued during the summer and 



early fall. 



METHOD OF DETERMINING HYDROCYANIC ACID 



At present there are no satisfactory quantitative methods for esti- 

 mating hydrocyanic acid obtained from organic material. All are open 

 to some objection. After considering several, the Prussian-blue method 

 was adopted as best suited for the purposes of the present investigation. 

 Because of simplicity in manipulation it is possible to run a large number 

 of determinations at the same time. The amount of hydrocyanic acid 

 obtained from the different samples was estimated colorimetrically, 

 using standard solutions containing known amounts of potassium cyanid. 

 One objection to the colorimetric measurements was the difficulty in 



' Contribution No. 92 from the Department of Chemistry, Agricultural Experiment Station of Kansas 

 State Agricultural College. 



* Credit is due Mr. Carl M. Conrad for efficient assistance in making the determinations reported in this 

 paper. 



' SWANSON, C. O. HYDROCYANIC ACID IN SUDAN GRASS AND ITS EFFECT ON CATTLE. Ill JoUr. Amer. 



Soc. Agron., v. 13, no. i, p. 33-36. 1921. 



Journal of Agricultural Research Vol. XXII, No. 3 



Washington, D. C. Oct. 15, 1921 



7x Key No. Kans.-J7 



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