WATERPROOF COMPOSITIONS. Many patents have been taken out for methods of rendering cloth and leather water proof. In 1835 Mr. Hellewell, of Salford, took out a patient for a solution, which, by immersion, should render cotton and other fabrics waterproof; it is a composition of rock alum and whiting in water, and its action is aided by a subsequent application of soap and water. Mr. Hall, of Doncaster, patented in 1839 a method of waterproofing cloth by im mersion ; one solution described consists of alum, white lead, and water ; and another of alum, white lead, acetic acid, and water ; and the cloth, after steeping in one of these solu tions, is passed through a solution quick Effie, and a third time through a solution ol :belled Irish Moss, Which acts as a Mucilage, ;There are other patents of a somewhat siiriil ;eltatecter 03 the abeeffi, and there have also liffinerods inetheds pithlished but not patented.
The einfaed•application of species of ter 'itish has been the subject of many patents. A composition was introduced for this pur pose some yowl ago, formed of linseed oil, .pipe-clay, burnt tether, white lead, pounded pumice-stone, and one or two other sub stances. This was not intended as a Water proof composition for ordinary clothing, but rather for terpattling, awnings, Coach-top covers, boat-cloaks, and other coarse terials. Mr. Newberg's patent, taken Out in 1140, is for a Mode of applying waterproof 'composition in such a way as to leave one side of the Woeen fabric free from its in fluence, thereby presenting to the eye a ture nearly resembling that of ordinary cloth. The application of a layer of cement, gum, or Varnish between two other substances, with a view to render the inner one impervious to' water, has been practised tinder many dif ferent modifications, including that Which is known by the name of the inventor, tosh. the year 1824 Mr. Weise,.of Ber mondsey, devised a peculiar kind of fabric, which consists of fibrous materials spun into yarn; the yarn is dipped in eseutchbee solu tion before weaving; and in order to render the meshes impervious to water, the cloth is drawn over a heated cylinder, whereby the composition is so far melted as to flow into them. The waterproof or Macintosh cloth is
made by applying a layer of dissolved thout to cotton or other cloth. The cloth is stretched upon frames and brushed over with it ; and the surfaces of two such pieces, while in a partially damp state, are laid one upon another, and pressed between rollers till they firmly and inseparably unite. The double fabric thus produced is wholly imper vious to water, and is at the same time free from any adhesive substance on the surface.
The useful application of air for beds, cushions, seats, and similar articles, is de pendent on the formation of air-tight cases ; and this air-proof quality is brought about by nearly the same means as waterproofing. When a bag has been made of eaoutehotie or similar cloth, and rendered also air-tight by • somewhat similar means at the seams, air • may be passed into it as a substitute for more 1 solid .materials. In practice there are some very heat arrangements adopted in effecting this. Temporary air-seats or cushions are made by forming a bag of air-tight cloth, I c perfectly enclosed at every part except one corner, Where is inserted a small tube and ar stop-coeb, capable of admitting or preventing eotninufficatlon feem the interior to the ex tenor. The cock being opened, and the tube applied to the mouth, air is blown into the cushion, until it expands to the desired degree of fulness; the cook is then closed, and the air remains imprisoned. In this state the cushion is of a more equable kind than anyone stuffed with eolid materials; and if the envelope be well made, it will retain its efficacy for a long time. When not in use, such a cushion can have the air expressed from it, and may then be folded into a small apace.