Fire-Proofing, a term applied to processes by which fabrics or buildings are rendered proof against taking fire. Cloths saturated with mineral paint are rendered less liable to inflame from falling cinders or sparks, but cannot be made to withstand continued heat. Several methods have been devised for rendering wood fire-proof. In the United States wooden roofs are partially secured from fire by covering them with a coating of gravel, secured by mixture with coal tar or asphaltum; but of course this affords protection only against sparks or cinders. The English war department several years ago made experiments to test the utility of an application of one of the cheap soluble alkaline silicates, as the silicate of soda. Painting the wood with a strong solution of the salt was very useful. But the best results were obtained by going over the coating of the silicate of soda with another of lime whitewash, and after this had stood a few hours coating it with another stronger solution of the soda. The first solution, it is directed, should be prepared by mixing with one measure of the thick sirup of silicate of soda three measures of water; the wood should be brushed over with this, as much being laid on as the wood can be made to absorb.

When nearly dry, the lime wash of creamy consistence is applied, and after this has become moderately dry, the solution prepared with two parts of sirup to three of water is laid on with the brush. The covering thus prepared adhered very well, even when exposed to a stream of water and to rains; the former when striking the wood in the shape of a jet only slightly abraded it, and it was not easily removed by applying heavy blows to the wood. It was found that when the silicate was prepared so as to mix readily with water, one pound was sufficient to cover 10 square feet, and at the rate of £20 per ton of the sirup, the cost of the silicate for this amount of surface is only about twopence. By this application to the timbers and other woodwork of houses, they may be rendered comparatively safe from fire; but for important structures, the most thorough protection is in the use of wrought-iron beams, built into the Avails of brick or stone, and of iron or other incombustible material for the partition walls, floors, roof, and stairs.

The most efficient methods in use in the United States are described in the article Beam. Even buildings thus constructed in the most perfect manner may be completely ruined if filled with combustible goods that become once thoroughly ignited; for the beams when heated must expand, and with a force against the walls that cannot be resisted. Cast-iron beams and columns have been shown to be more objectionable even than wood; for on becoming heated they rapidly lose their strength, and are liable to give way suddenly, and much sooner than timbers even when consuming.