This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This has always supplied an excellent insecticide to gardeners in the form of washes, fumigants, and vaporizers, the active principle of which is nicotine. It may be used in the form of powder, like Hellebore, or as a wash when steeped in hot water, or in a concentrated form in cakes and liquid. The waste ends of cigars, cigarettes, and tobacco from pipes may be preserved to make a cheap and effective insecticide. Three pounds of tobacco, steeped in boiling water and allowed to cool for six hours, will make 10 gal. of insecticide, which will be improved by the addition of 1/2 lb. of soft soap.