12 N. J. Agricultural Experiment Stations, Bulletin 355 



The same charge used in the same house may give very 

 different results. Taking for comparison figures 12 and 15, 

 both made in the fern house with a charge of i^/o ounces, it is 

 seen that at ii/o minutes after the fumigation started the average 

 concentration throughout the house was 11. 5 for No. 15, while 

 for No. 12 it was only 9.06. This discrepancy continues, as 16 

 minutes later the concentration in No. 15 was 10.26, while in 

 No. 12 it was 7.55. Only at the end of the fumigation was 



€^ 



HOUSE 

 PLAN 



cAPActrr 



l,37lcu H 

 AV 5.41 



I ^ 3 4 5 6 7 Q 9 10 II iZ 13 14 15 16 17 18 19 20 2/ 22 

 MINUTES 



Fig. 5. Graph of Fumigation No. 5 



A, left bench; B, right bench; C, left collecting tube; D, 

 middle collecting tube; E, right collecting tube; F, comb collect- 

 ing tube. 



there a close approximation, as at 35 minutes after the fumiga- 

 tion started the concentration in No. 15 was 6.29, while in No. 12 

 it was 6.89. Likewise, in two fumigations in which double the 

 amount of cyanide was used in one case as was used in the 

 other, the resulting concentrations of gas were not in the same 

 proportion. Figures 13 and 14 show this relation. Using the 

 average concentrations throughout the house in both cases, No. 

 13 showed an average of 31.5, 1% minutes after the fumigation 

 started, while No. 14 showed less than this, 27.12 with a charge 

 twice as great. Seventeen minutes later the average for the 3- 

 ounce charge was 19.43 while for the 6-ounce charge it was 

 23.64; 35 minutes later the average concentration for the whole 



