LEAD ARSENIATE. 



79 



They can be obtained on wheels to work by hand, on carts to work by 

 gasolene engines, or portable outfits on the plan of a fire-engine are pre- 

 pared which work by steam and 

 cover a large area daily. 



The choice of insecticides for 

 each case is a matter requiring 

 care. The principal insecticides 

 are shortly described with their 

 uses. The formulae for prepar- 

 ing these mixtures are given in 

 Appendix A, page 283. 



Lead Arseniate. 



This is practically the only 

 useful stomach poison available 

 in India, and no other is 

 required. Lead arseniate is a 

 form of arsenic which combines 

 the best qualities of the older 

 stomach poisons, London Purple, 

 Paris Green, etc., with qualities 

 peculiar to itself. It is a white 

 substance, procurable in powder 

 or paste, which is insoluble in 



water, harmless to plants, and easy of application in the form of liquid 

 or powder. It has a considerable power of resisting rain and so remaining 

 on the plant in wet weather, and its white colour shows up on the 

 plants to which it is applied. It is poisonous to cattle and human 

 beings if taken in any but a very small dose, but it can be applied at 

 such strength as to render plants poisonous to insects though not to 

 cattle. Sprayed on to plants at the rate of one pound in 60 to 100 

 gallons of water, it is effective as a poison to insects, and its efficacy 

 is increased by adding jaggery, gur or molasses and lime. The usual 

 mixture is one pound of arseniate, three pounds of lime and six pounds 

 or less of any form of low grade sugar or molasses with the necessary 

 water. It can be used at double this strength with full safety to 

 plants. Applied as a powder, it is best mixed with twenty parts of 

 wood ashes, road dust, cheap flour, powdered lime, or any other cheap 

 neutral powder : it can then be placed in rough cloth bags and shaken 

 oyer the plants, 



Fm. 96. 



Success Sprayer used on the ground for 

 spraying trees. 



