CHAPTER XV 



INSECTICIDES 



Arsenic in its various compounds is the cheapest and most 

 efficient insecticide in common use. For this purpose only 

 compounds insoluble in water can be used, since arsenic In 

 solution is injurious to foliage, even when present in only small 

 quantities. 



Arsenic 



White arsenic, arsenious oxid (AS2O3), is a white powder. 

 It is the cheapest form in which arsenic can be obtained. It is 

 soluble in water and therefore very injurious to foliage. A 

 cheap and efficient insecticide may, however, be prepared from 

 it by the following methods : 



For use with Bordeaux inixture only. — Sal soda, 2 pounds ; 

 water, 1 gallon; arsenic, 1 pound. Mix the white arsenic 

 into a paste and then add the sal soda and water, and boil 

 until dissolved. Add water to replace any that has boiled 

 away, so that one gallon of stock solution is the result. Use 

 one quart of this stock solution to 50 gallons of Bordeaux mix- 

 ture for fruit trees. Make sure there is enough lime in the 

 mixture to prevent the caustic action of the arsenic. 



For use without Bordeaux mixture. — Sal soda, 1 pound ; 

 water, 1 gallon ; white arsenic, 1 pound ; quicklime, 2 pounds. 

 Dissolve the white arsenic with the water and sal soda as above, 

 and use this solution while hot to slake the 2 pounds of lime. 

 Add enough water to make 2 gallons. Use 2 quarts of this 

 stock solution in 50 gallons of water. 



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