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ARSENICALS. 



Several arsenical poisons are available for use, such as Paris green, 

 Scheele's green, arsenite of lime, and arsenate of lead. These all contain 

 arsenic and destroy insects which eat them with their food. In the 

 work herein reported Paris green and arsenate of lead were used. A 

 good quality of Paris green is very satisfactory, and this poison is per- 

 haps more generally used than all other arsenicals combined. It 

 should be used on apple at the rate of about 1 pound to 150 gallons of 

 water or Bordeaux mixture, in which case it is simply added to the 

 mixture, having previously been worked into a paste with water, to 

 insure its more thorough distribution in the fungicide. Many growers 

 use it at the rate of 1 pound to 100 gallons of spray, but there is danger 

 of injury to apple foliage at this strength. When used alone in water 

 the milk of lime from slaking 2 or 3 pounds of good stone lime for 

 each 50 gallons should be added, which will neutralize any free arsenic 

 and prevent burning. The same result is secured by the excess of 

 lime in the Bordeaux mixture. 



The arsenate of lead was purchased from the manufacturer and 

 used at the rate of 2 pounds for each 50 gallons of Bordeaux mixture. 

 This arsenical, as found on the market, usuallj^ occurs in the form of a 

 thick paste, which must be entirely worked free in a small amount of 

 water before being added to the spray tank. 



Arsenate of lead has been found preferable to Paris green by some 

 experimenters, as a nmch greater quantity may be used without injury 

 to the foliage, and it adheres longer. However, when used with Bor- 

 deaux mixture Paris green is not readily washed off by rains, is 

 apparently as satisfactory as the former, and at the strength used 

 costs less. 



Scheele's green is similar to Paris green, but contains no acetic 

 acid. Being a finer powder, it remains in suspension longer, and 

 costs about one-half less. 



Arsenite of lime is nmch the cheapest of the arsenicals used in 

 spraying, and has been found to be quite efhcitmt. It may be pre- 

 pared according to the following fornuila: 



White arsenic pound . . 1 



Sal soda (crystals) pounds. . 4 



Water gallon. . 1 



All of the ingredients are boiled together for a few minutes, or 

 until dissolved, and any water lost by evaporation added. This 

 constitutes a stock solution, which will keep indefinitely, 1 pint being 

 used with each 40 or 50 gallons of Bordeaux mixture or water. If 

 used with water, the milk of lime from slaking 2 or 3 pounds of good 

 stone lime must be added to produce the arsenite of lime and the 



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