66 
the same amount would kill other plants, as the plum tree. 
Plants made sensitive by certain climatic conditions, as by con 
tinuous moist and warm weather without sunshine, suffer much 
more severely from an application of this and similar insecti- 
cides at such times than at others. Before applying any ar- 
senical poisons to plants upon a large scale it is always best to 
try their effects upon a few, so that the mixture can be made 
just strong enough to kill the insects and not to injure the 
plants. It has been found that milk of lime almost entirely 
prevents the injurious effects of arsenical poisons upon the 
leaves. Milk of lime can be prepared by filling a barrel nearly 
full of air-slaked lime, and adding a sufficient amount of water 
to entirely fill the barrel. After standing undisturbed for some 
time the clear water above the lime is milk of lime. This can 
be demonstrated by blowing the air from the lungs through it, 
when it will become milky. 
Dry Application—As a general rule, Paris-green should be 
mixed with one hundred times its weight of perfectly dry flour, 
sifted wood ashes, road dust, land plaster, air-slaked lime or 
some similar substance. ‘To apply this dry mixture it is neces- 
sary to dust it over the plants at a time when there is no wind, 
and when the leaves are moist, as they usually are very 
early in the morning. In this case most of the dust will adhere 
to the leaves and remain there for a long time. Still any dry 
application, except upon a small scale, is always a very waste- 
ful one. 
Wet Application.—One pound of Paris-green to one hundred 
and fifty gallons of water is a safe mixture with which to kill 
nearly all insects that possess a biting mouth; it will not kill 
the foliage of any cultivated plants grown in Minnesota. If it 
should become necessary to spray the same plants repeatedly, 
later applications may be reduced in strength. As Paris green 
does not readily mix with water it should first be made into a 
paste, and then mixed with the amount of water required. Up- 
on the leaves of some plants, as those of cabbage, this fluid will 
not readily adhere, but in such a case we can readily overcome 
the difficulty by adding a little dissolved soap to the mixture, 
or by adding stale milk. 
