WATERPROOFING. Textile fabrics, whatever be their character, are pervious to water from two causes : namely, the existence of minute spaces between the individual fibres of the yarn, whether of silk, cotton, wool, or flax; and the rectangular meshes consequent on the process of weaving. To close up these minute channels, as likewise the pores of leather, so as to impart a waterproof quality-to the material, has been the object of a large number of patents, as well as of recipes which have not been patented. Mr. Hellewell took out one of the earliest of these patents, for a solution which should render cotton and other fabrics waterproof. According to this plan, for a quantity of woven material equal to 1000 lb. weight, there are used 120 lb. of rock alum, 80 lb. of common whiting, and 200 gallons of water. This mixture is intended, by the chemical action of its ingredients, to yield a solution of alumine, with which the cloth is saturated. After the saturation the cloth is passed quickly through a vessel containing a solution, at a temperature of 100° Fahr., of yellow soap in water, the proportions being 3 lb. of soap and 30 gallons of water to 50 lb. of cloth. This latter process is for the purpose of fixing the alumine in the interstices of the cloth, and enabling it to resist the action of water. The cloth is finally washed, to free it from any impurities. Mr. Hall patented a method of waterproofing cloth by immersion. He describes two kinds of solution employed for this purpose. pat, two ounces of pulverised alum are dissolved in a pint of distilled water ; one ounce of dry white lead is rubbed down in another pint of water ; and the two solutions being mixed and allowed to settle, the supernatant liquor constitutes the required agent. 2nd, one ounce of dry white-lead is rubbed down in half a pint of water ; one ounce of pounded alum is dissolved In another half-pint of water ; and these two solutions, together with two fluid drachms of acetic acid, are mixed together, and allowed to settle. When the cloth has been immense(' in the supernatant liquor resulting from either of the above solutions, it is passed through a solution of quicklime, and a third time through a solution of boiled Irish mom, which acts as a mucirage. One more example will suffice :—Itoil half an ounce of Russian isinglass in a pound of soft water till dissolved ; dissolve an ounce of alum iu two pounds of water ; dissolve a quarter of an ounce of white soap in a pound of water ; strain these solutions separately through linen, and then mix them all together. Beat this liquid till it simmers, and apply it with a brush to the wrong side of the cloth, on a flat table. 11'hen dry, the cloth is brushed lightly
with water. The intention of this process is to render the cloth im pervious to water, but not to air.
1'lle surface-application of a species of waterproof varnish has been the subject of many patents. Messrs. Mills and Fainnan introduced a composition, formed of 100 lb. of linseed oil, 40 lb. of pipeclay, and a small quantity of burnt umber, white-lead, pounded pumimatone, and one or two other oubstanees. These ingredients were melted together and ground to a smooth paintliku state, and then applied to the surface of the fabric with largo knives, the cloth being stretched over wooden frames. When one surface was thus coated and dried, the other was similarly treated. This was not intended as a waterproof composition for ordinary clothing, but rather for tarpauling, awnings, coach covers, boat-cloaks, and other coarse materials. Mr. Newberry's patent is for a mode of applying waterproof composition in such a way as to leave one side of the woven fabric free from its influence, thereby presenting to the eye a texture nearly resembling that of ordinary cloth. The method consists in saturating the cloth with the waterproof com position, and exposing one surface only ; in such a way, that the atmosphere, or artificial heat, may harden the composition on that surface into a dry membranous film ; while the other side, after being kept moist during the drying of the first, is cleansed from the com position by means of spirit of turpentine. Mr. Newberry describes three modes of effecting this object. In the first mode the cloth or woven fabric is stretched over a frame, and after being saturated with the composition, is allowed to float on a layer of oil till the upper surface is dry ; after which the lower surface is cleansed from the composition. In the second mode the cloth is stretched double, or in two plies, over a frame, saturated with the composition, and then left to dry on the exterior surfaces, the contact-surfaces remaining =Lit until the time of removal. In the third mode recourse is had to a roller, on which the cloth is coiled, and a flat table of slate, stone, varnished wood, or other substance non-absorbent to the comporsition. The table is coated with a layer of the composition, and the cloth, being uncoiled and laid down upon it, is pressed and rolled till every part becomes wetted by the composition beneath. In this tiny the upper surface may be cleansed while the lower is in contact with the table, and the latter is then exposed to a drying process.