EXERCISE XLIV 



THE STUDY OF KEROSENE EMULSION 



Material. Laundry soap, kerosene. 



Apparatus. Granite kettle, cooking-burner, stirring-rod. 



This insecticide is used for many scale insects, and also for 

 some other of the sucking insects, such as the plant lice, etc. 

 The emulsion is usually made in the form of a stock solution 

 and diluted to the required strength when needed. The regular 

 formula is 



Laundry soap ^ lb. 



Kerosene 2 gal. 



Soft water 1 gal. 



Laboratory formula. Weigh out one ounce of laundry soap, 

 cut into small pieces, and dissolve it in one pint of water. Allow 

 this solution to boil, remove it from the fire, and add one quart of 

 kerosene. Stir the mixture violently until it becomes a creamy 

 mass that will not separate. This usually requires from five to 

 ten minutes. The emulsion is now finished. Describe kerosene 

 emulsion. Name several kinds of insects upon which it is used. 

 What is an emulsion ? 



For use, dilute one part of the emulsion with eight or ten 

 parts of water for hard-bodied insects and with fifteen or twenty 

 parts of water for soft-bodied insects. Why is it detrimental to 

 use the kerosene alone, and what is the destructive principle in 

 the emulsion ? 



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