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

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?