46 



FUMIGATIOISI FOR THE CITRUS WHITE ELY. 



for 170 cubic feet of space, all of the rates are more or less greater 

 than those used in the experiments in which from 95 per cent to 

 99.9 per cent of the insects were killed. It is evident that the increase 

 in number of cubic feet per ounce of potassium cyanid from 110 to 

 170 must be calculated at a rate which is in direct proportion to the 

 percentage of increase in cubic contents. The method employed in 

 these calculations is shown in Table VIII, which gives the figures 

 with the ratios ranging from 1 : 1.0 up to 1 :3.6. 



Table VIII. — Rates of dosage as ajf'ected by ratio of niunber of square feet in surface to 

 the number uf cubic feet in volume. 



In Table VIII the number of cubic feet of space per ounce of potas- 

 sium cyanid increases toward 170, representing the rate when the 

 ratio is 1 to infinity, and the dosage increases in rate (= decrease in 

 the number of cubic feet per ounce of potassium cyanid) as the units 

 of cubic contents become infinitely small in number as compared 

 with the units of square measure of leakage surface. Using the 

 above rates as a basis, the doses for trees measuring from 10 to 76 

 feet over the top have been calculated. The dimensions of the tented 

 trees and volumes of the inclosed spaces have been calculated in 

 accordance with the formula? given in the preceding pages. Table IX 

 gives the original calculations, while in the appendix the recommended 

 doses alone are given, in a form more convenient for practical use in 

 the field. 



