New YorkK AGRICULTURAL EXPERIMENT STATION. 299 
Irom the data in these tables it appears: (1) That it is unsafe 
to leave peach trees exposed to the action of the gas for periods 
of 12 hours no matter what weight of potassium cyanide per 
cubic foot is used; (2) that all vigorous trees, even those as 
tender as peach can be safely treated with as much as 24 ozs. of 
98 per ct. potassium cyanide per 100 cu. ft. (.75 grm. per cu. ft.) 
for a period not exceeding 30 minutes, providing the treatment 
is given while the trees are dormant; (3) that peach trees which 
have their vitality reduced by attacks of the scale are Habie 
to be injured after April Ist by use of 24 ozs. of potassium cyan- 
ide per 100 cu. ft.; but the injury is not usually such that the 
trees do not recover and make a better growth than while 
infested; (4) that peach can be treated in the orchard for inter- 
vals varying from 30 to 60 minutes with as much as 1} ozs. 
potassium cyanide per 100 cu. ft. (.50 grms. per cu. ft.), even after 
fruit buds show color; (5) that walnut and chestnut will stand 
the same treatment as peach. 
The tests made in 1900, under tents and hence liable to error, 
indicate that plums and cherries are similar to peach in resist- 
ance, and that pears cannot stand 1 ozs. of potassium cyanide 
after the flower buds are exposed. At this time the injury was 
confined principally to the flower buds, but even where these 
were injured the entire setting of fruit was not destroyed. 
Johnson has reported injury to peach in Maryland by use of 
about one-half the above amounts of potassium cyanide per cubic 
foot. It will be shown under rules for estimating contents of 
tents and fumigators that, through an error, Johnson has actu- 
ally used much more than the amount he recommends as safe. 
CauTtion.—It should be remembered that the larger amounts 
tested apply only to trees in orchards where the gas comes in 

contact with the ground. 
EFFECT OF THE GAS ON THE SCALE-INSECT. 
The effect of the gas upon the insects is not as easy to deter- 
mine as its effect on the trees. Frequently on branches thor- 
oughly encrusted with this pest not over one per ct. of tlhe 
