158 Principles of Plant Culture. 



the soda and potash compounds, all these may be used 

 either as a dry powder or with water. 



284. The Arsenic Compounds are effectual as insect de- 

 stroyers, even when largely diluted. AYhen applied in 

 water, however, they are liable to injure foliage in pro- 

 portion to the amount of soluble arsenic they contain. 

 When insoluble in water, they require stirring to keep 

 them in suspension. 



285. Paris Green (arsenite of copper), when pure, is a 

 nearly insoluble compound and may be safely used upon 

 the foliage of most plants, diluted at the rate of one 

 .pound to two hundred gallons of water. For the peach 

 and nectarine it should be diluted one-half more. Pure 

 Paris green dissolves without sediment in ammonia water. 



286. White Arsenic (arsenious acid) is slightly soluble 

 in water, and hence is dangerous to foliage unless used 

 with care. If applied immediately after its addition to 

 the water, it may be safely used upon the foliage of the 

 apple, plum and cherry at the rate of one pound to fifty 

 gallons, but constant stirring is required to keep it in 

 suspension. 



287. London Purple (arsenite of lime, with certain im- 

 purities) often contains soluble arsenic, and like white 

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

 applied to many plants 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 considerably 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. 



