NEW JERSEY 



Agricultural Experiment Stations 



bulletin 355 



September i, 1921 



A STUDY OF THE DISTRIBUTION OF HYDROCYANIC 

 ACID GAS IN GREENHOUSE FUMIGATION* 



WILLIAM H. WOOD KOMP, M. Sc. 



Introduction 



One of the most puzzling features in greenhouse fumigation 

 is the variation in amount of cyanide which in practice is used 

 to produce insect-killing strength of hydrocyanic acid gas. This 

 large variation may be accounted for in a number of ways : the 

 influence of temperature and moisture conditions ; the influence 

 of condensation of moisture ; and the tightness of the green- 

 house. Of these factors the last is apparently the most import- 

 ant. The operation of these three factors is such as to render 

 the accurate gradation of dosage in greenhouses impossible, as 

 the amount of cyanide which will produce insect-killing strength 

 of hydrocyanic acid gas in one house will be entirely different in 

 another house of the same cubical contents. This fact has led 

 to the great differences in recommendations for dosage in va- 

 rious publications dealing with the subject of hydrocyanic acid 

 gas fumigation, and is the reason for the empirical methods used 

 by the greenhouse man in actual practice. 



To overcome this element of uncertainty, it was proposed to 

 construct a machine by which the exact concentration of HCNt 

 in any part of the greenhouse being fumigated could be accu- 

 rately determined, and to carry out a series of experiments to 

 determine the part of the house from which the gas should be 

 drawn to give an index of killing strength throughout the iiouse, 

 and also to endeavor by means of minimum dosage experiments 



* This study was undertaken and carried out in the season of 

 1916-17 under the direction of Dr. Thomas J. Headlee, Entomologist 

 of the New Jersey Agricultural Experiment Stations. The author 

 takes this opportunity of acknov/ledging the constant encouragement 

 received by him. 



t HCN — Hydrocyanic acid gas. 



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