CONTENTS 



Page. 



Introduction 91 



I. Analyses of chemicals used for the production of hydrocyanic-acid gas 91 



Sulphuric acid 91 



Cyanid samples 92 



II. Proportion of cyanid, sulphuric acid, and water for best yield of gas 93 



Potassium cyanid 93 



Sodium cyanid - 93 



III. Action of mineral acids on cyanids and hydrocyanic acid 96 



Action of sulphuric acid on hydrocyanic acid 97 



Action of hydrochloric acid on hydrocyanic acid 98 



Effect of the presence of sodium chlorid in cyanids on the yield of hydrocyanic- 

 acid gas in fumigations 99 



Description of apparatus 100 



Details of manipulation 100 



Results of experiments 101 



Ammonia formed from the decomposition of the cyanid 102 



Effect of the presence of sodium nitrate in cyanids on the yield of hydrocyanic- 

 acid gas 103 



Summary : 104 



ILLUSTRATION. 



Page. 

 Fig. 13. Laboratory apparatus used in the decomposition of cyanids and col- 

 lection of the liberated hydrocyanic-acid gas 100 



in 



