116 INJURIOUS INSECTS OF 1903. 



41. Paris Green- — 



Although there are several better arsenical insecti- 

 cides, Paris Green is the most popular. In samples studied 

 at this Station we find that even the Paris Green from the 

 best manufacturers contains at times a great deal of un- 

 combined arsenic. Therefore, it is to be expected that 

 some persons get better results than others in its use. 

 Some will have the foliage burned very badly and others 

 not at all. In another part of this bulletin the analyses 

 of samples of Paris Green are reported. It would be well 

 to study the figures there given before purchasing one's 

 next supply of Paris Green. 



Arsenical insecticides are used to combat the various 

 insects that cat the foliage and the fruit. 



Paris Green may be applied either by dusting or spray- 

 ing. In dustmg, to prevent the Paris Green from being 

 applied too thickly at one place, i pound of Paris Green is 

 mixed thoroughly with 25 to 50 pounds finely slaked 

 quicklime or cheap flour. This is dusted over the leaves 

 of the vines, trees, etc., in the early morning when the 

 dew is on. For methods of application see page 154. 



In spraying use i pound of Paris Green ; 

 2 to 4 pounds of fresh lime ; 

 160 to 200 gallons of water. 

 Slake the lime gradually, sprinkling in the Paris 

 Green, then add the rest of the water. (Mass. Bui. 80. 

 1902.) 



Or, make a paste of the Paris Gr«en and water and 

 then add to the mixture of lime and water. 



42. Petroleum — (See Crude Petroleum.) 



43. Potassium Sulfid — 



A stock solution is made as follows: 



Formula : 



Potash, 32 pounds; 



Sulphur, finely ground, 37 pounds ; 



Salt, 2 pounds ; 



Water, 50 gallons. : 



