12 



States Division of Entomology,* Colby, of California,! and others : — 



Arsenate of soda 10 ounces. 



Acetate of lead 24 



Water 150-200 gallons. 



The arsenate of soda and the acetate of lead (sugar of lead) should 

 be dissolved separately and then poured into a tank containing the re- 

 quired amount of water. A white precipitate of lead arsenate is im- 

 mediately formed, and when thoroughly stirred, is ready for spraying. 

 Its finely divided condition keeps it in suspension for hours and thus 

 simplifies the work of spraying. The preparation may be used several 

 times stronger without the least danger of scorching the most delicate 

 plants. When sprayed upon the foliage, it forms a coating which ad- 

 heres so firmly that it is but little affected by ordinary rains. 



The average wholesale price of the arsenate of soda and acetate of 

 lead, as given by an Ontario wholesale drug firm, is 9 and 7 cents per 

 pound, respectively. This would make the cost of the materials used 

 on the above formula a little over 16 cents, which would be as cheap, if 

 not cheaper, than Paris green. 



Arsenite of Lead. Prof. Colby, California Agricultural Experiment 

 Station, Bulletin No. 151, gives the following formula and directions 

 for the preparation of arsenite of lead : — 



Arsenite of soda 12 ounces. 



Acetate of lead 4 pounds. 



Water 150 gallons. 



Dissolve the ingredients separately and then pour them into a 150- 

 gallon spray tank filled with water. A milky mixture ready for spraying 

 is obtained. This mixture is said to remain in suspension fifteen times 

 as long as the finest grained Paris green. 



Calcium Arsenite. Several formulae for making this compound have 

 been published. There appears to be no doubt about the insolubility of 

 the compound when it is used immediately after it is prepared, but when 

 allowed to stand for days or weeks before applying, there may be some 

 decomposition take place and soluble arsenites be formed which will 

 destroy foliage. 



The formula proposed by Prof. Taft of Michigan is as follows : 

 "Boil one pound of white arsenic and two pounds of lime in two gallons 

 of water for forty minutes and then dilute as required." He further 

 states that when one pound of the arsenic, prepared as above, is used 

 in every 300 to 400 gallons of water, it has been equal to Paris green for 

 destroying the codling-moth and curculio, while one pound in 150 to 

 200 gallons of water is used upon potatoes. When used in Bordeaux 

 mixture it is not necessary to use any more lime, otherwise he recom- 

 mends the addition of a small amount of lime when diluting. 



* U. S. Department of Agriculture, Division of Entomology, Bull. 41. 

 t California Experiment Station, Bull. No. 151. 



