4 
15 minutes without material injury. This will kill about 90 per 
cent of the plant-lice, but will not kill thrips. The use of the gas 
for carnations needs to be more carefully investigated before it is 
recommended. The same is true of chrysanthemums, on which it 
has been tried with only partial success, the young growth being 
very sensitive. 
Grapes under glass.—The gas has been used with success in 
New Zealand * for mealy bugs (Dactylopius adonidum L.) at the 
rate of one-third of an ounce 98 per cent cyanide to 100 cubic feet. 
This is equivalent to nine-hundreths gram per cubic foot. The gas 
is liberated after dark and left in till next morning, when thorough 
ventilation is given. It largely escapes, however, during the night. 
The treatment is said not to injure the plants in the least. 
Tomatoes.—Dr. Jabez Fisher, in ‘‘ American Gardening” (Oct. 29, 
1898), reports using the gas for ‘‘white fly” (Aleyrodes sp.) on 
tomatoes. The gas from one ounce of pure cyanide of potassium for 
each 1,000 cubic feet left in the house over night killed all the insects 
without injury to the plants. This method has not yet proved suc- 
cessful with us in any case, but it should nevertheless receive careful 
trial by other experimenters. 
CUBIC CONTENTS OF THE HOUSE. 
It is necessary in every case to determine with great care the 
cubic contents of the house, frame, or box in which the fumigation 
is to be made. To illustrate: Fig. 2 shows cross sections of two 
styles of greenhouse structures now in general use. At the left is 
an even span house 100 feet long, 12 feet wide, 2 feet on the sides, 
and 5 feet 6 inches from the surface of the beds to the ridge, with a 
walk 14 inches wide and 15 inches deep. To determine accurately 
the number of cubic feet in this or a house of similar construction: 
First, make a rough drawing showing a cross section of the house; 
second, divide the space into triangles and rectangles by drawing a 
line connecting the two wall plates and one from the ridge at right 
angles to this; mark on each its respective length in feet and inches. 
Compute the number of cubic feet in each of the rectangles and tri- 
angles in accordance with the following method. In the even span 
house shown at the left, the number of cubic feet of space in the walk 
is found by multiplying the width by the depth by the length, thus: 
Multiply 1 foot 2 inches by 1 foot 3 inches by 100 feet; reducing to 
inches we have 14 inches multiplied by 15 inches by 1,200 inches 
equals 252,000 cubic inches; dividing this result by 1,728, the number 
OD 
of cubic inches contained in a cubic foot, we have 145.83 cubic feet. 

* Fourth Report, Dept. of Agr., New Zealand. 1896. Pp. 141-143. 
