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It is now on the market as a dry powder, white or colored with a dye, 
ready for immediate use, costing about 10 cents a pound, and also in 
paste form. Arsenate of lead may be used at any strength from 3 to 
15 pounds to the 100 gallons of water without injury to the foliage, 
and in this respect is much safer on delicate plants than any other 
arsenical. Its use is advised where excessive strengths are desirable 
or with delicate plants where scalding is otherwise liable to result. 
With this insecticide there is an advantage in using the freshly pre- 
pared and wet mixture in that it gives a more filmy and adhering coat- 
ing to foliage, the same fineness not being secured when it has been 
dried and repulverized. 
In point of solubility and corresponding danger of scalding the 
foliage these arsenicals fall in the following order, the least soluble 
first: Arsenate of lead, Scheele’s green, Paris green, and London pur- 
ple. The difference between the first three is not great in the particu- 
lars noted nor also in point of effectiveness against larvee or other 
insects. London purple is ordinarily considerably less effective. 
HOW TO APPLY ARSENICALS. 
There are three principal methods of applying arsenicals. The wet 
method, which consists in using these poisons in water in the form of 
spray, is the standard means, secures uniform results at least expense, 
and is the only practical method of protecting fruit and shade trees. 
The dry application of these poisons in the form of a powder, which is 
dusted over plants, is more popular as a means against the cotton 
worm in the South, where the rapidity of treatment possible by this 
method, and its cheapness, give it a value against this insect, in the 
practical treatment of which prompt and economical action are the 
essentials. This method is also feasible for any low-growing crop, 
such as the potato, young cabbages, or other plants not to be immedi- 
ately employed as food. The third method consists in the use of the 
arsenicals in the form of poisoned baits, and is particularly available 
for such insects as cutworms, wireworms, and locusts in local inva- 
sions. 
The wet method.—Either Scheele’s green, Paris green, or London 
purple may be used at the rate of 1 pound to 100 to 250 gallons of 
water, or 1 ounce to 6 to 15 gallons. The stronger mixtures are for 
such vigorous foliage as that of the potato for the Colorado potato- 
beetle, and the greater dilutions for the more tender foliage of the 
peach or plum. An average of 1 pound to 150 gallons of water is a 
good strength for general purposes. The poison should be first made 
into a thin paste in a small quantity of water and quicklime added in 
amount equal to the poison used to take up the free arsenic and 
remove or lessen the danger of scalding. An excess of lime will do 
no injury. The poisons thus mixed should be strained into the spray 
