April. '15] 



WOODWORTH: FUMIGATION PRACTICE 



303 



have a dose equal to that of a tent 22 x 22. It will not be necessary to 

 explain here why one fifth is the correct factor.^ 



The adoption of this plan of relative sizes makes it possible to pre- 

 sent a table of dosage in an exceedingly simple form, and to make the 

 adjustments for different degrees of leakage also very easy. 



DOSAGE TABLE 



Ounces of Sodium Cyanid 



Relative Leakage xxx .25%x x x% 



Size 64 61 58 56 53 50 47 44 42 40 37 35 32 30 28 26 24 22 20 18 16 15 13 11 10 ft. 

 40 36 32 28 24 20 18 16 14 12 10 9 8 7 6 5 4i 4 3^ 3 2| 2 1| 1| IJ 1 f § i 



Relative size equals distance over the tent plus one for each 5 ft. of difference between the 

 measurements. 



Leakage more than .25% is read to the left and if less to the right, one number for each .05% 

 more or less than .25%. Do not fumigate trees smaller than number of feet equal to .00% of 

 leakage. Holes produce leakage requiring the use of the next number to the left when equiva- 

 lent to a triangular tear half as many inches long as relative size and quarter as wide as long. 



Stronger dosage for purple scale may be read one or two numbers to the left and 



Weaker dosage for black scale one or two numbers to the right 



Acid corresponding with any dose is given 2 numbers to the left and 



Water 3 numbers to the left of the acid dose. 



In the foregoing table the approximate size of the minimum dose is 

 indicated by asterisks except for .25 per cent which is printed to em- 

 phasize that this table is for that degree of leakage. 



The first line of figures gives the relative sizes corresponding with 

 the doses on the following line. The intervals range from 1-3 and the 

 dose intervals from J oz. to 4 oz. This corresponds quite closely with 

 previous tables and with actual practice. 



The table in fact will be soon memorized. It will be noticed that 

 the intervals of the upper line just above 10 and 15 are 1 and that other 

 intervals are two except just below 35 and 40 and above 44. The 

 doses corresponding to 10, 20, 30, and 40, are f, 2 J, 5, 9, and with 64 

 is 32 oz. The intervals in the dose line are by quarter ounces to 2, half 

 ounces to 5, ounces to 10, two ounces to 20 and four ounces to 40. 



The acid and water dose is usually calculated mentally; if to be read 

 from the table cut a card as wide as five numbers. ' Held against the 

 table the two corners will indicate cyanid and water and a line on the 

 card may be drawn to point to the acid dose. Or prepare a card by 

 cutting out a hole or notch wide enough to enclose five numbers and 

 have- this line to indicate acid as before. 



The mental effort in calculating the relative size will not be found to 



1 Bulletin 220, Cal. Agr. Exp. Sta., p. 5. 



