24 



BULLETIN 907, U. S. DEPARTMENT OF AGRICULTURE. 



presented in experiments 1 to 27 appears to indicate that the greatest 

 safety demands fumigation at temperatures below 80° F., unless the 

 dosage is weak or the exposure short, and this condition has been 

 corroborated by experiments in orchard treatment. 



SUDDEN CHANGES IN TEMPERATURE DURING FUMIGATION. 



The following four experiments, when viewed in the light of data 

 given in the preceding experiments, show the effect of a sudden 

 increase in temperature immediately before or during the first few 

 minutes of exposure and followed by a fluctuation of several degrees 

 during the remainder of the treatment. The actual temperature 

 during the gas treatment in the first three experiments was 86° F. or 

 above, while in experiment 27 it was cool, ranging from 61° to 70° F. 



EXPERIMENT 24. 



Condition during fumigation, dark, 86°-92° F. 



Condition before fumigation, dark, 64° F. 



Dosage, 1 ounce NaCN. 



Date, September 23, 1915, 6.10-6.50 a. m. 



Plants in each test, 4; total, 20. 



Remarks: Temperature of fumigatorium was raised from 64° to 92° F. imme- 

 diately before fumigation and held at 86°-92° F. throughout the exposure. Maxi- 

 mum temperature for day, 93° F. at 2 p. m. 



Results. 



Condition after fumigation. 



Dark, 65° F. 



Shade. 67° F. 



Dark, 73° F. 



Shade, 73° F. 



Sun. 73° F. 



4 



4 



4 



4 



5 



EXPERIMENT 25. 



Condition during fumigation, shade, 86°-92° F. 



Condition before fumigation, dark, 65° F. 



Dosage, 1 ounce NaCN. 



Date, September 23, 1915, 7.10-7.50 a. m. 



Plants in each test, 4; total, 20. 



Remarks: Temperature of fumigatorium was raised from 73° to 92° F. immediately 

 before fumigation and held at 86° to 92° F. throughout exposure. Maximum sun 

 temperature for day, 93° F. at 2 p. m. 



Results. 



■ - 



Condition after fumigai ion. 



Dark, 65° F. 



Shade, 67° F. 



Dark, 75° F. Shade, 75° F. 



Sun, 75° F. 



4 



4 



4 



4 



5 



