The application of a layer of cement, gum, or varnish between two other substances, with a view to reuder the inner one impervious to water, has been practised under many different modifications, iucludiug that which is known by the name of the inventor, Macintoah. Mr. Weise of Bertnondsey devised a peculiar kind of fabric, which seems to belong to the class now under consideration. This fabric was to be used either as &material for hats and bonnets, in lieu of the felted beaver, or as a cloth for other garments. The materials consisted of beaver-fur, musk-fur, hare's wool, Spanish wool, flax, down, and waste silk, any or all of which were to be combined, according to the hind of fabric required. The materials were carded, roved, and spun into yarn, in the manner of cotton; and this yarn was soaked in a solution of caontehonc, or Indian rubber, to render the interstices between its fibres waterproof. The yarn was then woven into a textile, fabric ; and in order to render the meshes impervious to water, the cloth was drawn over a heated cylinder, whereby the resinous composition was so far melted as to flow into therm. The last part of the process was to raise a pile or nap on the surface by means of teazles or brindle& In Mr. patent of 1824, the use of a cement between two layers of cloth was introduced. The cement, or thick elastic varnish, was made by dissolving caoutchone in a small quantity of coal -oil, the proportions of the ingredients, varying according to their quality. This invention led to the remarkable aeries of processes for waterproofing noticed under CAOUTCHOCC MANUFACTURE.
The attempta to render leather waterproof depend in general on the filling up of the small pores which have previously admit fed the tannin ; the substance imbibed being such as will repel or resict water. Many such methods have been proposed at different times, of which It will be enough to mention a few. Melt over a slow fire a quart of Wilts' linseed oil, a pound of mutton suet, three-quarters of a pound of yellow bees'avax, and half a pound of common resin, or smaller quantities in the like relative proportions; and with &is moisture saturate the leather of new boots or shoes, while the latter is slightly wann. Another method is to melt two ounces of yellow betw'avax,
two ounces of Burgundy pitch, and two ounces of turpentine, in a pint of linseed oil, and with this mixture to saturate the warmed liesthltr. The ' Journal of the American Institute' gives the two followinu Boil together for half an hour one quart of linseed oil, two ounces of resin, and half an ounce of white vitriol, to which add four ounces of spirits of turpentine and two ounces of white oak sawdust, and apply this mixture to the leather by means of a brush. 2. Apply a coating of tallow to the leather; and after this has dried, coat it again with a mixture of one part of copaiba balsam with two of naphtha. Another mixture for this pnrposo consists of six ounces of caoutchouc boiled for two hours in two quarts of linseed or ncats'-foot oil. Lastly, a mode hai been much recommended of applying a hot mixture of two parts tallow and one part resin, with which' the leather may be com pletely saturated, the resin imparting an autiseptio quality to the tallow.
Oue of Mr. Siovier's contrivances is for rendering leather at once elastic and waterproof. A thin sheet of leather is cemented to a thin sheet of solid caoutchone by a caoutehouo solution, and kept under pressure for five or six days. The compound fabric thus formed is nearly inelastic, because the leather has temporarily suspended the elastic power of the caoutehoue; but by the application of a tempera tin-e about equal to 180° Fehr., the caoutchoue partially collapses, and the leather assumes a corrugated surface, similar to Morocco leather. The leather, rendered thus elastic and waterproof, is then manufactured into boots and shoes or other articles.