IMPERMEABLE

is the epithet given to any kind of textile fabric, rendered water-proof by one or other of the following substances :— 1. Linseed oil to which a drying quality has been communicated by boiling with litharge or sugar of lead, . 2. The same oil holding in solution a little caoutchouc. 3. A varnish made by di olving caoutchouc in rectified petroleum or naphtha, applied between two surfaces of cloth, as described under Macintosh’s patent . See Caoutchouc . 4. Vegetable or mineral pitch, applied hot with a brush, as in making tarpauling for covering goods in ships. 5. A solution of soap worked into cloth, and decomposed in it by the action of a solution of alum; whence results a mixture of acid fats and alumina, which insinuates itself among all the woolly filaments, fills their interstices, and prevents the pa age of water. 6. A solution of glue or isingla , introduced into a stuff, and then acted upon by a clear infusion of galls, whereby the fibres get impregnated with an insoluble, impermeable, pulverulent leather. 7. Plaster work is rendered impermeable by mixing artificial or natural asphaltum with it.