Insects and Insecticides. 
21 
1. WHITE ARSENIC. 
While this is the cheapest of the arsenical poisons, it is used but 
little, except for the purpose of making arsenical compounds with 
other substances, such as lime, copper and lead. Because some 
States have passed laws requiring a high percentage of arsenic in 
Paris green, arsenic has been used as an adulterant of Paris green 
and thereby working an injury to the purchaser if not a benefit to 
the manufacturer of it, because arsenic is much cheaper than Paris 
green, and when it is mixed with the latter it greatly increases its 
liability to burn foliage. The reason that white arsenic burns 
foliage badly is it dissolves in water and, when in solution, it pene¬ 
trates the leaves and kills the living tissue. Arsenical mixtures 
must never be in solution , but only in suspension , in the water that is 
used to distribute them upon foliage. 
2. ARSENIC BRAN-MASH. 
Prepared by mixing one pound of arsenic and six to ten pounds 
of bran together, with just water enough to thoroughly moisten the 
mass. Some prefer to add a pound of sugar to the above in order 
to cause the particles of bran to adhere to each other, so that it may 
be distributed in little balls pressed together with the hands or with 
a paddle. This poisoned bran is used for the destruction of grass¬ 
hoppers in orchards and vineyards where it is not possible to use a 
hopper-pan. 
3. PARIS GREEN. 
This poison in a pure state is said to be composed of three sub¬ 
stances—arsenious acid, acetic acid, and copper oxide—united in a 
chemical combination. The percentage of arsenic may vary con¬ 
siderably, as these substances do not always combine in exactly the 
same proportions. The range is nearly always between 55 and 60 
per cent arsenic, with an average of about 58 per cent. *Mr. J. K. 
Haywood, one of the chemists in the Department of Agriculture at 
Washington, D. C., says that the chemical composition of Paris 
green should be: 
Per cent. 
Arsenious acid.58.65 
Copper oxide.31.29 
Acetic acid.10.06 
Pure Paris green is one of the very best of the arsenical com¬ 
pounds for the destruction of insects, and the reports of many 
analyses in different States do not indicate that this poison is often 
found greatly adulterated upon the market. If adulteration is sus¬ 
pected, or if the poison is being purchased in any considerable 
quantity, it is advisable to test its purity in some way. Pure Paris 
^Farmer’s Bull. No. 146, U. S. Dept, of Agr. 
