136 



Journal of Agricultural Research voi. xxii. No. 3 



EFFECT OF ACID OR ALKALI ON HYDROCYANIC ACID AFTER IT IS 



LIBERATED 



An experiment was performed to show what effect acid or alkaline 

 solutions have on the hydrocyanic acid after it is liberated. The green, 

 macerated material was digested overnight in measured amounts of 

 water. Enough standardized acid or alkali was then added to give the 

 normality desired, and distilled. The results are given in Table XVI. 



Table XVI. — Effect of acid and alkali on hydrocyanic acid after it is liberated 



Solution added. 



H2SO4 

 Hcl . . . 

 H3PO4 

 NaOH 



HON obtained after treatment with solutions of- 



Nlr. 



Mgm. 



9 

 16 



Nlo.g. 



Mgm. 



N/o.i. Njo.os. 



Mgm. 



16 



20 



2 



Mgvi. 



14 



18 



18 



O 



Water. 



Mg7n. 



20 

 20 



No hydrocyanic acid passed over in the first distillate from the sodium- 



hydroxid solution. The mixture was acidified with sulphuric acid and 



then distilled with the results given in Table XVI. While the results 



obtained in this experiment are not very uniform, they do show that 



hydrocyanic acid can be obtained from acid and alkaline solutions if the 



hydrocyanic acid is in a free condition before the acids are added. The 



experiment also appears to show that the addition of acid or alkali 



resulted in diminishing the amount of hydrocyanic acid obtained. The 



experiment was also tried by digesting the grass in sulphuric acid and 



sodium hydroxid of the normalities N/i, N/0.2, N/o.i, and N/o.o^ and 



then neutralizing before distilling. In no case was any hydrocyanic acid 



obtained. 



INFLUENCE OF WEATHER 



From a sample taken June 23, when there had been no rain for three 

 weeks, 27 mgm. of hydrocyanic acid were obtained. On June 30, after 

 a heavy rain and a week of good growing weather, during which there 

 was plenty of moisture, 30 mgm. were obtained. On July 24, when 

 there had been a period of dry weather, the amount obtained was 7 mgm. 

 The next day, following a rain during the night, the amount was 16 mgm. 

 Several experiments indicated that the largest quantity was obtained 

 when the plant was in the most vigorous growing condition. This is 

 contrary to a common belief that stunting has some effect in increasing 

 hydrocyanic acid. On the contrary, the potential amount may be 

 lessened. Determinations were made on samples collected at sundown 

 and also before sunrise. The data obtained were not conclusive in deter- 

 mining the effect of light on the potential amount of hydrocyanic acid 

 present. 



