TO PRESERVE WOODWORKS THAT ARE EXPOSED TO WET OR DAMP.
1. For those of an extensive nature, such as bridges, &c. The Hollanders use for the preservation of their sluices and floodgates, drawbridges, and other huge beams of timber exposed to the sun and constant changes of the atmosphere, a certain mixture of pitch and tar, upon which they strew small pieces of shell broken finely—almost to a powder—and mixed with sea-sand, and the scales of iron, small and sifted, which incrusts and preserves it effectually.
2. A paint composed of sub-sulphate of iron (the refuse of the copperas pans), ground up with any common oil, and thinned with coal-tar oil, having a little pitch dissolved in it, is flexible, and impervious to moisture.
3. Linseed oil and tar, in equal parts, well boiled together, and used while boiling, rubbed plentifully over the work while hot, after being scorched all over by wood burnt under it, strikes half an inch or more into the wood, closes the pores, and makes it hard and durable either under or out of water.
4. For fences, and similar works, a coating of coal-tar, sanded over; or, boil together one gallon of coal-tar and 2½ lb. of white copperas, and lay it on hot.