67 
LONDON PURPLE. 
This by-product in the manufacture of aniline colors con- 
tains about forty-three per cent. of arsenite of lime; the rest 
is composed of aniline lime, insoluble residue, some little 
oxide of iron and water. As the material 1s cheap it would 
be used much more frequently if it came in convenient pack- 
ages and not in bulk. At all events it is just as good an in- 
secticide as Paris-green and can be used in the same manner, 
dry or with water. It is much lighter than Paris-green, and 
more finely divided, remains better in suspension in water, and 
can therefore be applied more evenly with less stirring. It ad- 
heres better to the foliage and is consequently not readily 
blown away by the wind or washed down by the rains. As most 
of the commercial London-purple contains some free and solu- 
ble arsenious acid we must add some milk of lime to prevent 
injury to the foliage. If this precaution be kept in mind we 
have in this substance avery superior insecticide. 
A good proportion in which to apply London-purple is one 
pound to two hundred gallons of water, with an addition of 
about one pailful of milk of lime. It is always well to mix 
London-purple with the water just before use and not to leave 
the mixture standing over night, as may be safely done when 
Paris-green is used. In a dry application we can dilute this 
insecticide with the same substance as we use with Paris: green. 
WHITE ARSENIC. 
White arsenic, though very cheap, is too dangerous to use, 
being so readily mistaken for some edible substance on account 
of its white color, and also because it is more injurious to fo- 
liage, as it is to some extent soluble in water. If it has to 
be used it should be very much diluted, and the mixture 
should be applied when quite freshly mixed and only with a 
large amount of milk of lime. 
In using such virulent poisons as Paris-green, London-pur- 
ple and white arsenic it is important to keep in mind the fol- 
lowing rules: label the stored material very plainly ‘‘Poison”; 
do not handle the poison with your hands; never apply it 
against the wind; do not use upon leaves of fruit soon to be 
eaten; and use it of no greater strength than is absolutely nec- 
essary. 
