New York Agricultural Experiment Station. 341 



arsenite instead of an aceto-arsenite of copper, and 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 8 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 added to 

 produce a more or less coarsely crystalline product. 



In a publication of the Department of Agriculture, Mr. Mar- 

 latt 9 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 10 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 



« Insect Life, 7: 408-411. 



» U. S. JDept. Agr., Div. Ent., Bui. 2, n. ser. 



io U. S. Dept. Agr., Div. Ent., Bui. 6, n. ser. 



