CYANOGENBSIS IN SUDAN GRASS: A MODIFICATION 

 OF THE FRANCIS-CONNELL METHOD OF DETERMIN- 

 ING HYDROCYANIC ACID 



By Paul Menaul, Assistant Chemist, and C. T. DowELL, Chemist, Oklahoma Agri- 

 cultural Experiment Station 



There have been a few cases reported from this and other States of 

 the poisoning of cattle while pasturing on Sudan grass. Prof. H. D. 

 Hughes of the Iowa State College was so kind as to send us information 

 which he had obtained on the subject. It seems that no determina- 

 tions of the hydrocyanic acid in Sudan grass have been made except those 

 made by FrancisS and for that reason the writers decided to determine 

 the percentage of the acid present in the grass at several stages of its 

 growth. 



Our first sample was cut on June 1 6 when the grass was 1 5 inches high. 

 Other samples were taken at intervals of one week thereafter until the 

 grass was cut for hay. There had been plenty of rain, and the grass had 

 grown very rapidly. 



The method used for determining the acid was that employed by 

 one of the writers^ in determining the amount of the acid in kafir. 

 The grass was cut fine, bruised thoroughly in an iron mortar, and then 

 covered with water in a flask and kept at 40° C. for two hours. After 

 this it was made more strongly acid with tartaric acid and distilled into 

 30 cc. of a 2 per cent solution of sodium hydroxid. The cyanid was 

 precipitated as Prussian blue. After being burned in a muffle furnace 

 the iron oxid was weighed, and from this weight the weight of hydro- 

 cyanic acid was calculated. One or two of the last determinations 

 were made by the use of the Francis-Connell method^ as modified by 

 the writer. The results are shown in Table I. 



From this table there is seen to be a decrease in the hydrocyanic acid 

 with growth. This would be expected since similar results have been 

 obtained with other varieties of sorghums. More of the acid is present 

 in the leaves than in the remainder of the plant. This has been found 

 by others to be true for other plants. A number of determinations 

 which are not given in the table show that there is more hydrocyanic 

 acid in the plant in the morning than in the afternoon. The writers 



■ Franos, C. K. poisoning of live stock while feeding on plants of the sorghum group. Olda. 

 Agr. Exp, Sta. Circ. Inform. 38, 4 p. 1915. 



* DowELL, C. T. CYANOGENESis IN ANDROPOGON SORGHUM. In Jour. Agr. Research, v. 16, no. 7, 

 p. 175-180. 1919. 



* Franos, C. K., and Connell, W. B. the colorimetric method for determining hydrocyanjc 

 ACID IN PLANTS WITH SPECIAL REFERENCE TO KAFIR CORN. In Jour. Amer. Chem. Soc, V. 35, no. 10, 

 p. 1624-1628. 1913. 



Journal of Agricultural Research, Vol. XVIII, No. 8 



Washington, D. C. Jan. 15, igao 



tk Key No. Okla.-a 



(447) 



