82 VEGETABLE GARDENING. 



kinds of insects. It is otten adulterated and can seldom be 

 obtained of good quality. It also deteriorates very quickly 

 when exposed to the air. On these accounts it is often very 

 difficult to get satisfactory results from that which can 

 be obtained at the stores. When used it should be diluted 

 with about five times its bulk of flour, with which it should be 

 kept in a tight vessel for at least twenty-four hours before 

 using, in order to get best results. It should always be kept 

 in an air-tight receptacle. 



Paris green is a refuse product composed of arsenious acid 

 and copper and is probably as safe to use as any arsenic 

 compound. It is only very slightly soluble in water, and is 

 used with water at the rate of one pound to one hundred or 

 more gallons of water: it is also used when mixed with dry 

 substances, at the rate of one pound to fifty pounds of flour or 

 one hundred pounds of land plaster, road dust or sifted coal 

 ashes. In using it with water, the addition of an equal 

 amount of milk of lime often prevents injury to leaves. 



London purple is composed of arsenious acid and lime. It 

 is often much cheaper than Paris green but varies more in its 

 composition. On account of its being lighter than Paris 

 green it does not settle so quickly when put in water. It is 

 used in the same manner as that substance. When used in 

 water an equal amount of milk of lime should always be added 

 to neutralize the free acid which it sometimes contains in in- 

 jurious quantities, and which may burn the foliage of tender 

 plants. London purple adheres to the foliage of plants longer 

 than Paris green. 



Tobacco is very useful for destroying some kinds of insects 

 in the garden and greenhouse. It is especially effective 

 against plant lice and soft-skinned hairless caterpillars. 

 Where smoke from it can be confined around the plants, as in 

 greenhouses and hotbeds, it is common to use it in a smudge, 

 but when thus used it should be kept from blazing. It is also 

 used in powdered form to keep off some insects. A more 

 common and effective way of using it, is as a decoction in 

 water at the rate of one pound of tobacco stems, leaves or 

 dust to two gallons of water. The tobacco should be 

 boiled in the water for twenty minutes. When cold the de- 

 coction should be used undiluted with a syringe, spray or 



