Water-Proof, a term applied to those stuffs, which have undergone certain chemical or mechanical processes, and thus become impermeable to moisture.

Having already stated, under the heads of Boot and Leather, the most proper means of rendering those articles water-proof, we shall at present confine our attention to the expedients that have been devised for making linen and wool-ten cloth, paper, etc. capable of resisting humidity.

In July, 1797, a patent was granted to Mr. Henry Johnson, for his invention of a vegetable liquid, the design of which is to bleach and cleanse woollen, or other stuffs ; to prepare them for the reception of a certain compound, calculated to render them not only water-proof, but also more durable and elastic, when manufactured into articles of dress, which he terms Hydrolaines. - In order to obtain first the vegetable liquid, the patentee directs horse-chesnuts, or the rinds and kernels of oranges, that are usually thrown away, or the offals and gall of fish, to be boiled for four or five hours ; after which they are suffered to cool and settle, for a few days : in cases where these substances cannot be easily procured, 8 quarts of water may be added to every pound of British barilla, and the mixture allowed to dissolve for two or three days. Next, one pint of pear -ashes, or of purified kelp, or wood-ashes, must be added to either of these preparations; and, after the whole has been duly mixed, for 24 hours, a certain portion of Ryegate-lime is slacked in the compound, for the purpose of imparting the caloric; of precipitating the carbon of the ashes; and moderating the causticity of the liquor. Now 40 quarts of water are to be boiled with one quart of fish, linseed, or other oil 5 adding to this decoction half an ounce of the salt Of sorrel, or of sugar, or of the rectified salt of tartar; the object: of which is to combine the oil with the water. Lastly, after this composition has stood for 12 hours, it is to be strained, and 1 quart of such oily water to be mixed with every 12 quarts of the liquid, prepared in the manner above described : when the mixture is completely settled, it forms, what the patentee calls, a blanching lixivium. The linen, woollen, cotton, or silk stuffs, hats, or leather, are to be immersed in such lixivium, and extended on a frame. Caoutchouc is then to be dissolved in spirit of turpentine (the smell of which may be dissipated by the addition of equal parts of oil of wormwood and spirit of wine), so as to form a varnish : this liquor must now be applied to the wrong side of the stuffs that are to be prepared, by means of a solid piece of India rubber; and minute shreds of cloth, wool, silk, or worsted, should be sifted over the varnish: in the course of 2 or 3 days, it will be perfectly dry; and the shreds, by their adhesion to the dissolved caoutchouc, will form a lining impermeable to water.

water-proof. - As the patentees have not thought proper to publish the particulars of their process (though such concealment is contrary to the nature of Letters Patent), we shall briefly remark from our own observation, that their method appears to be a simple impregnation of cloth with wax previously dissolved, and incorporated with water, by the addition of pure vegetable alkali, or pot-ash. This being the cheapest and most expeditious mode of reducing wax to a fluid state, we are farther inclined to believe that our conjecture is well founded; because all the woollen cloth prepared in the manufactory of Messrs. Ackermann, Suardy, and Co. feels somewhat harder than such as has not been waxed: for the same reason, it will stand a shower of rain Only so long as it has not been subject to friction ; and we understand from those who have worn patent water-proof coats, that in the sleeves particularly, they are very apt to admit moisture through the different folds. Nevertheless, their process is entitled to attention; and it deserves to be adopted principally in those cases, where the manufacture is not liable to be impaired by friction; such as coverings for tents ; for horses exposed to the rain when at rest; and especially for paper in which gunpowder, or steel and other goods, are to be packed.

The following simple process is stated to be that employed by the Chinese, for rendering cloth waterproof: Let an ounce of white wax be dissolved in one quart of spirit of turpentine; the doth be immersed in the solution, and then suspended in the air, till it be perfectly dry. By this method, the most open muslin, as well as the strongest cloths, may be rendered impenetrable to the heaviest showers; nor will such composition fill up the interstices of the finest lawn; or in the least degree affect the most brilliant colours.