Plants as Affected by Animal Parasites. 165 



tate of lead (sugar of lead) in one gallon of water and 

 separately 10 ounces of arsenate of soda in three quarts 

 of hot water. (Use wooden, earthen ware or glass ves- 

 sels.) Pour the separate solutions into 100 gallons of 

 water. A white precipitate of lead arsenate ready for 

 spraying immediately forms in the tank; its fine, floc- 

 culent condition keeps it in suspension for hours, and 

 of all arsenic compounds it is the most easily kept sus- 

 pended in water." 



Arsenate of lead prepared ready for use is offered 

 under different trade names, as "Disparene," etc. 



287. London Purple (arsenite of lime, with certain 

 impurities) often contains soluble arsenic and like 

 white arsenic, must be used with caution. It may be 

 safely applied to many p 7 ants at the rate of one pound 

 to two hundred gallons of water, if put on immediately 

 after its addition to the liquid, but for the peach it 

 should receive greater dilution. London purple is con- 

 siderably cheaper than Paris green. 



The addition of fresh milk of lime to water, to which 

 white arsenic or London purple has been added, largely 

 prevents their tendency to injure foliage. 



Both Paris green and London purple, when perfectly 

 mixed with 150 parts, by weight, of land plaster, or an 

 equal bulk of any other cheap, harmless powder, are 

 satisfactory for destroying the potato beetle and many 

 other leaf -eating insects (307). 



288. Compounds of Arsenic are Deadly Poisons and 

 should always be handled with the greatest care. 



