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.
Nicotine in some concentrated form has always formed the staple fumigating material. It is now to be had concentrated in cake or liquid form, and, although apparently expensive, is really very effective. The cakes or liquid is placed in a shallow metal dish seated on a metal stand. A small methylated-spirit lamp is placed beneath, and when lighted dissolves the cakes or liquid into fumes that are diffused throughout the houses. These fumes are fatal to insect pests of all kinds, and if properly applied are harmless to almost every plant. It is not wise, however, for the gardeners to remain long after the lamps are lighted.