306 JOUENAL OF THE ROYAL HORTICULTURAL SOCIETY. 
be wrapped in smaU pieces of blotting paper it is easy to drop in the 
required amount of cyanide without the slightest risk of breathing the 
fumes of prussic acid, which are evolved on contact with the acid. 
For greenhouse work, proceed as follows : If the house be under 10,000 
cubic feet one vessel will suffice ; if over, provide a vessel for each 10,000 
cubic feet. Arrange the ventilators so that they can be opened from 
without. 
Operate from oiUsidc the house by tying the cyanide in a paper packet 
to a string at the end of a bamboo or other pole and dropping the cyanide 
into the jar of acid. Always add the acid to the water and not vice 
versa. 
The foliage of the plants should be dry. A temperature not exceeding 
60 deg. F., and preferably of 50 deg. F., is requisite. Above 60 deg. F, 
there is risk of injury to the foliage. Fumigation must not be done in 
strong light, and is best carried out after sunset. Open all doors and 
ventilators after the prescribed time, and on no account enter the house 
within one hour. 
For Mealy Bug we recommend 3 oz. cyanide ; 5 oz. acid ; 15 oz. 
water per 1,000 cubic feet, either before the vines bloom, or when grapes 
are colouring, or after the crop has been gathered. At either of these 
stages no harm results to either foliage or fruit. Avoid fumigation when 
the vines are in bloom, or before the grapes have commenced to ripen. 
For ordinary greenhouse pests, such as aphis, dolphin, whitefly, slugs, 
woodlice, red-spider, and caterpillars, a dose not exceeding 1| to 2 oz. 
cyanide, 4 oz. acid, 7 oz. water, per 1,000 cubic feet, has proved itself 
satisfactory. 
