545 
How To REcKON CuBIC Capacity. 
Consider the covered tree as a cylinder. To calculate its 
volume, multiply half the width by itself, then by the height ; 
then multiply by 3, or, to be more accurate, by 33. This is ex- 
pressed by the formula V = 7 R?H, 7 = 3:14; R is the radius of 
the circumference ; H the height. Thus a tree eight feet wide by 
eight high would be 4 x 4 x 8x3 = 384 cubic feet, or say 400 
cubic feet. Cyanide of potassium, 1}0z. per 100 cubic feet, would 
be 6ozs., half as much again, or 9Yozs. of sulphuric acid, with half 
as much again of water as acid, or 13}0zs., making a total of 
28}0zs., or TJozs. of the combined chemicals for every 100 
cubic feet. 
DosEes AND TIME. 
Cyanide of potassium, 98 per cent. purity, loz. per 100 cubic 
feet. 
Sulphuric acid of commerce, 1} fluid oz. per 100 cubic feet. 
Water, 2} fluid oz. per 100 cubic feet. 
Norzt.—If fumigating in the winter for the more resistant 
scales, and particularly San Jose scale, the doses might be increased 
to : Cyanide of potassium, 1} oz. ; sulphuric acid, 2} fluid oz. ; and 
water, 3} fluid oz. per 100 cubic feet. 
The tree having been covered, one operator lifts the bottom of 
the tent : the other, after having poured in the earthenware bowl the 
quantity of water and acid (N.B.—Pour the acid slowly into the 
water to prevent spurting), crawls underneath and places that bowl 
under the tent close to the trunk of the tree, but not touching it. 
Then at arm’s length he breaks the paper cover of the cyanide of 
potassium and drops the number of packets required into the bowl 
holding his breath meanwhile and crawling back ; the tent is then 
let down, earth heaped up on the circular canvas collar, and the tent 
allowed to remain on the tree 45 to 60 minutes. Much of the poor 
work sometimes done is to be attributed to insufficient time. 
N.B.—The mere fact of covering a tree in full growth by means 
of an air-tight tent, for an hour or two, while the sun is up and the 
plant breathing, is enough to choke it and cause it to drop its 
foliage ; therefore, be careful to only fumigate, if in the growing 
months, in the cool of the evening or early in the morning. If the 
tree is dripping wet or is covered with beads of dew injury to the 
foliage might result. 
When the time is over, the operator and his assistant uncover 
the tree by lifting the tent up, holding their breath while so doing, 
when another tree can be covered and treated without pausing: 
Should a battery of half a dozen tents be in use, a considerable 
number of trees can be fumigated at once and without waste of 
e. 
ig Bury the residue left in the bowl after fumigation. 
