6 



saleratus, baking powder, and other materials used in cooking, 

 it would be unwise in the extreme to recommend it, especially 

 if it be in solution, for insecticidal purposes. 



Paris Green. — This is an arsenite of copper and was 

 brought into prominence as an insecticide for the first time 

 in this country in 1869. It was first used for destrojnng 

 the potato beetle. It varies somewhat in composition but 

 there is generally over fifty per cent of arsenic in that which 

 has not been adulterated. The commercial Paris green is 

 undoubtedly more or less adulterated, and that sold in the 

 market for the destruction of insects probably never contains 

 fifty per cent of arsenic, and may contain no more than 

 thirty per cent. It is practically insoluble in water and may 

 be applied either dry or wet. In the former case it should 

 be well mixed with some fine powder as a diluent ; plaster, 

 air-slaked lime, flour, road-dust, and finely-sifted wood 

 ashes, all answer the purpose fiiirly well, though lime or 

 plaster are usually preferable. The proportion of poison to 

 diluent varies greatly Avith different users, — one part poison 

 to fifty, and even one hundred, of diluent, will usually be 

 efi'ective, if the mixing be thoroughly done. Care should 

 be taken to apply lightly and to all parts. To most low 

 plants this application can be easily and rapidly made by 

 enclosing the powder in a muslin bag, which is shaken 

 over the plants. All dry applications are best made in 

 the early morning w^hen the dew is on, or after a shower. 

 If applied in water the amount of Paris green that can be safely 

 used varies according to circumstances. The opinions of 

 various scientific experimenters as to the proper propor- 

 tions are given' later on in the work. The arsenites, 

 either dry or in water, may be used against the difierent 

 potato beetles, the flea beetles, the cucumber beetles, the 

 cabbage w^orms (before the plants begin to form heads), 

 the codling moth, the tent caterpillar, the canker worm, the 

 curculio, and many other leaf feeding insects. 



The chief objection to Paris green is that it is so heavy 

 that it settles quickly to the bottom of the vessel, very 

 much more quickly than London purple, and consequently 

 should be kept stirred when using. It is also more expen- 

 sive than London purple. 



