Distribution of HCN Gas in Greenhouse Fumigation 15 



case the temperatures were 50° and 60° F. (See figures 2 and 4). 

 Using the average concentrations for two fumigations with 

 a 1.5-ounce charge, it is found that with a difference of ii°F. the 

 concentrations are lower at the higher temperature. (See figures 

 12 and 15.) But in two tests made with a ^-ounce charge and 

 a difference of 9°F. one showed a slight reduction in concentra- 

 tion at the higher temperature, while the other showed a large 

 increase at the higher temperature. While on the whole, the 



I — I I — 1 1 — I n r~\ 



H0U3E PLAN 



o 



CAPACITY 25,366 



CU.FT. 



/ 2 J 4 5 6 



y e & 10 II la 10 14 15 le n 



MINUTES 



Fig. 8. Graph of Fumigation No. 8 



A wall bench; B, middle bench; C, center bench; D, middle 

 bench-' E, wall bench; F, center collecting tube; G, middle col- 

 lecting tube; H, wall collecting tube; J, comb collecting tube. 



greater number of tests show that the concentrations tend to be 

 higher when the temperature is low, the discrepancies noted, to- 

 gether with the small number of tests made, render it impossible 

 to judge accurately of the effect of temperature. 



Distribution in Relation to Humidity 

 Taking the results of two tests made in a greenhouse of 

 25,000 cubic feet capacity, with approximately equal tempera- 

 ture (50°-52°F.) a difference of 11 per cent relative humidity 

 was accompanied by an increase of concentration with the high- 

 er humidity. However, another test in which the time interval 

 was 8 minutes less from the beginning of the fumigation than 

 in the tests described above, the concentration was only slightly 



