DOSAGE REQUIREMENTS. 



45 



Table VII. — Study of dosage rates. 



From a study of the data in the Table VII the writer concluded 

 that for a ratio of 1:1.5 the cyanid should be used at a rate very 

 near tol ounce to 110 cubic feet of space. Owing to the fact that 

 in all cases tented trees include less inclosed space than would a 

 regular figure which for purposes of approximate calculations has 

 been considered as equivalent, this rate would be higher for a reg- 

 ularly shaped inclosure whose cubic contents could be definitely cal- 

 culated. Probably 1 ounce to 100 cubic feet of space is nearer the 

 actual rate which the experiments indicate is necessary with the ratio 

 mentioned. This, however, is of little consequence in dealing with 

 sheet tents, for only the comparative volumes and dosage rates for 

 trees of different dimensions are required for practical purposes. 

 Having decided upon the adoption of 1 ounce of potassium cyanid 

 per 110 cubic feet of space with the ratio of 1:1.5, calculations were 

 made for tents with different ratios up to 1:3.6. Professor Gossard 

 reports" that 1 ounce to 170 cubic feet of space destroys all white 

 fly pupap in an air-tight fumigatorium. Considering that this rate 

 is approximately correct, an equivalent rate for the volume inclosed 

 by a sheet tent covering a tree would be more than 170 cubic feet in 

 the ideal form of inclosure upon which the calculations are based. 

 Experiments numbered X.3 and X.4, however, show that a rate not 

 less than 1 ounce for 126 cubic feet of space should be used when 

 the ratio is 1:2. When the ratio is increased from 1 : 1 .5 to 1 : infinity* 

 and the rate of dosage for this latter ratio is considered as 1 ounce 



aFla. Exp. Sta. Bui. 67, p. 652. 



& It is evident that if the numbei of cubic feet of space were infinitely greater than 

 the number of square feet of leakage surface, the rate of dosage required for an air- 

 tight fumigatorium would be sufficient. 



