New York AGRICULTURAL EXPERIMENT aaa 341 
arsenite instead of an aceto-arsenite of copper, el physically in 
being an impalpable powder while Paris green is crystalline. 
Green arsenite is said to be similar to if not identical with 
Scheele’s green, but according to samples sent by the manu- 
facturers to the Station the percentage of arsenious oxide may 
vary from 41.04 to 62 per cent, while Scheele’s green contains, 
theoretically, 52.94 per cent. 
WHEN FIRST USED AS AN INSECTICIDE: 
Mr. C. L. Marlatt of the United States Department of Agricul- 
ture, Division of Entomology, was probably the first to use green 
arsenite in place of Paris green. Mr. Marlatt® states that copper 
arsenite (green arsenite) was especially made for him in 1894, by 
a prominent manufacturer of Paris green and that it is in reality 
Paris green, without the addition of acetic acid which is ado to 
produce a more or less coarsely crystalline product. 
In a publication of the Department of Agriculture, Mr. Mar- 
latt? gives the results of experiments with this insecticide. He 
found that the action of the simple arsenite of copper on the foli- 
age of various plants used in the experiments was practically the 
same as Paris green. Again in a subsequent bulletin’? Mr. Mar- 
latt gives results of experiments with this and other arsenicals. 
ADVANTAGES OF GREEN ARSENITE OVER PARIS GREEN. 
In addition to the comparatively low cost of manufacture the 
principal advantage of green arsenite over Paris green is that, as 
it is so much more finely divided, it remains in suspension in 
water much longer. From experiments in the laboratory the 
writer found that the ordinary crystalline Paris green, when 
mixed with water at the rate of 1 pound to 150 gallons, would 
sink to the bottom of the jar in about five minutes, leaving the 
8 Insect Life, 7: 408-411. 
9U. 5S. Dept. Agr., Div. Ent., Bul. 2, n. ser. 
10 U. 8. Dept, Agr., Div. Ent., Bul. 6, n. ser. 
