170 The Spraying of Plants. 



The acid should first be poured upon the iron crystals, after 

 which the water may be added. This preparation is almost 

 identical with one already described under IKON SULPHATE, 

 and it is used for the same purpose. It has shown itself, in 

 the hands of Skawinski and others, to be a very efficient remedy 

 against grape anthracnose, being applied exclusively to dormant 

 wood. 



SKAWINSKI'S POWDER. 



Copper sulphate, powdered 22 pounds. 



Alluvial earth, or soot 33 " 



Coal-dust 165 " 



Mix thoroughly and apply in the form of a powder. The 

 preparation has been successfully applied in Europe for treat- 

 ing grape mildews, but is at present little used. 



SNUFF. Fresh snuff is as valuable as other forms of tobacco 

 in destroying insects. It may be used dry or as a decoction ; 

 for the latter use see Tobacco. When dry it is very service- 

 able in destroying insects where more energetic measures can- 

 not be taken, as in dwelling-rooms and small conservatories. 

 The powder should be blown upon the insects. 



SOAP. Probably all soaps are of value as insecticides, and 

 they were among the first remedies used. They kill by coming- 

 in contact with the insect, destroying it directly, as does kero- 

 sene, and probably also by closing the breathing pores, and so 

 smothering it. Common soap may be used at the rate of 



Soap 1 pound. 



Water 5-8 gallons. 



The proper strength of the preparation varies with the insect 

 and the plant to which it is applied. For plant lice, the 

 weaker solutions are sufficiently strong, but for mealy-bug and 

 similar pests the more concentrated forms are desirable. 



SOAP AND ARSENITES. 



Soap 4 pounds. 



Paris green or London purple 4 ounces. 



Lime 4 " 



Water 50 gallons. 



Dissolve the soap in 1 to 2 gallons of hot water, then add 

 the poison and the lime. Dilute just before using. This 



