CHAPTER I. 



INSECTICIDES. 



Arsenic. Kncwn to chemists as arseriious acid or wMte 

 oxide of arsenic. It is considered an unsafe insecticide., 

 as its color allows it to be mistaken for other substances ; 

 but in its various compounds it forms our best insecticides. 

 From i to 2 grains usually prove fatal to an adult ; 30 

 grains will usually kill a horse, 10 a cow and i grain or 

 less is usually fatal to a dog. In case of poisoning, while 

 awaiting the arrival of a physician, give emetics, and after 

 free vomiting, give milk and eggs. Sugar and magnesia 

 in milk is useful. 



Arsenites. Compounds of arsenic, in which arsenious 

 acid unites with some metallic base. The leading arsen- 

 ites used in destroying insects are Paris green and London 

 purple. 



PARIS GREEN. An aceto-arsenite of copper. When pure, 

 it contains about 58 per cent, of arsenic, but the commer- 

 cial article usually contains less, often as little as 30 per 

 cent. The following may be considered an average an- 

 alysis : Arsenic, 47.68 per cent.; copper oxide, 27.47; 

 sulphuric acid, 7.16; moisture, 1.35; insoluble residue, 

 2.34. It is applied either in a wet or dry condition, but in 

 any case it must be much diluted. For making a dry 

 mixture, plaster, flour, air-slaked lime, road dust, or 

 sifted wood ashes may be used. The strength of the mix- 

 ture required depends upon the plants and insects to 

 which it is to be applied. The strongest mixture now 



