CHAPTER IV. 



THE MATERIALS AND FORMULAS USED IN SPRAYING. 



No attempt has been made to render the following list of 

 materials and formulas complete. Such a record would require 

 many more pages than can here be devoted to the subject, and 

 in the end the result w r ould be of little value, since the majority 

 of the substances named would be such as have been found to 

 possess no real worth and have in consequence been discarded. 

 But many of the materials formerly recommended did possess 

 merit, and the principal reason for their abandonment has been 

 that other and more effective substances have been brought 

 forward, with the natural result that the first was displaced by 

 the newcomer. Such formulas are frequently interesting as 

 showing the steps which have been taken in the development 

 of preparations now recognized as the best, and they may also 

 assist in doing away with the idea that a fungicide or insecticide 

 must be made in accordance with a certain definite formula in 

 order to be effective. Nearly all the following directions will 

 bear considerable modification, and while it is highly desirable 

 that the rules be followed as closely as possible, since they have 

 been formulated after much experience, minor changes may be 

 made with comparative safety, and good results will still follow. 

 The cost of the more important substances is given ; the first 

 figure refers to the wholesale price, while the second one gen- 

 erally refers to the price when the article is bought at retail. 



ACETO-ARSEXITE OF COPPER. See Paris Green, page 121. 



ALCOHOL. A 30 per cent solution of alcohol when applied 

 in the form of a spray is useful in destroying aphis in green- 

 houses and in dwellings where the use of other methods is not 

 advisable. See also PYRETHRUM. 



115 



