LONDON PURPLE ITS COMPOSITION. 
149 
Worm Destroyer," which is essentially the same as the Lodi prepa- 
ration, and put Dp at the Xew Jersey works for the Galveston firm. 
Fifty grains of arseniate of soda and 200 grains of dextrine are to be 
dissolved in one gallon of cold water. The mixture formerly sold at the 
exorbitant price of 61 per pound, and is now offered for 50 cents per 
pound. It is put op in packages of and 100 pounds, and thus sold 
at a discount of 10 per cent. It is to be used at the rate of 4 ounces of 
the mixture to about 40 gallons of water, making the cost of one ap- 
plication per acre about 12) cents. It has been extensively used. 
Another 44 pest poison," also essentially the same as the Lodi prepa- 
ration, but faintly colored with rose aniline, is put up by the Kearney 
Chemical Works of New York, in i- pound packages, sold at 50 cents, 
and to be dissolved in CO gallons of water. 
This powder is obtained in the following manner in the manufacture 
of aniline dyes: Crude coal-oil is distilled to produce benzole. This is 
mixed with nitric acid, and form 8 nitro-benzole. Iron filings are then 
used to produce nascent hydrogen with the excess of nitric acid in the 
benzole. When distilled, aniline results: tothis are added arsenic acid, 
to give an atom of oxygen which produces rose aniline, and quicklime 
to absorb the arsenic. The residuum which is obtained by filtration or 
settling is what has been denominated » London purple," the sediment 
being dried, powdered, and finely bolted. The powder is, therefore, 
composed of lime and arsenious acid, with about 25 per cent, of car- 
bonaceous matter which surrounds every atom. Kxperiments which 
we made with it in 1878 impressed us favorably with this powder as an 
insecticide, and its use on the Colorado potato-beetle by Professors 
Budd and Bessey, of the Iowa Agricultural College, proved highly satis- 
factory. We were, therefore, quite anxious totest its effect on the Cotton 
Worm in the field on a large scale, and in the winter of 1878-V.) induced 
the manufacturers to send a large quantity for this purpose to the De- 
partment of Agriculture. The analysis made of it by Professor Collier, 
the chemist of the Department, showed it to contain : 
LONDON PI KPLE. 
Per cent. 
Rose aniline 
Arsenic acid 
Lime 
Insoluble residue 
Iron oxide 
Water 
Loss 
12. 46 
4:*. 65 
21.82 
14.57 
1.16 
2.27 
4. 07 
100.00 
Through the liberality of the manufacturers, Messrs. Hemingway & 
Co., a number of barrels of this powder were placed at our disposal 
