MECHANICS AND USEFUL ARTS. 101 



coating-, and liquified either by the action of heat, or by means of solvents, 

 such as spirits of turpentine, naphtha, etc. When it is desired to obtain a 

 harder coating, gallipot gum, yellow amber and resin, etc., may be added. 



The fabric to be coated is dipped into the material when hot, and in the 

 liquid state, from which it is withdrawn and made to pass between six 

 scrapers adjusted transversely above the vessel, so that any excess of the 

 material is removed, and drops into the vessel again. 



To Render Paper Impervious to Water. Take twenty-four ounces of 

 alum, and four ounces of white soap, and dissolve them in two pounds of 

 water ; in another vessel dissolve two ounces of gum arabic, and six 

 ounces of glue in the same quantity of water as the former. Add the two 

 solutions together, which is now to be kept warm. The paper intended to 

 be made water-proof is dipped into it, passed between rollers, and dried ; or 

 without the use of rollers, the paper may be suspended until it is perfectly 

 dripped and then dried. The alum, soap, glue and gum form a kind of ar- 

 tificial leather, which protects the surface of the paper from the action of 

 water, and also renders it somewhat fire-proof. 



PREVENTION OF DECAY IN STONE- WORK. 



The following are recent inventions, introduced or patented in England, 

 and on the continent, for the prevention of the decay of stone-work under 

 the various climatic influences to which it is exposed. By the employment of 

 a solution made of one part by weight of sublimed sulphur in eight parts of 

 linseed oil, heated in a sand-bath to a temperature of 278 degrees Fahren- 

 heit, the vegetable mucus of the oil is precipitated, the watery particles 

 evaporated, and their place supplied by the sulphur, which is readily taken 

 up by the oil at the above temperature. The solution should be applied by 

 a common painter's brash, until the stone will absorb no more. Stone thus 

 indurated becomes almost equal to granite in hardness, and, as far as a test 

 of four years can prove, not only shows no symptoms of decay, but actually 

 increases in hardness. 



Another invention, patented by Mr. H. C. Page, of London, has for its 

 object the preservation of the beauty, color and value of marblo and stone, 

 as well as their sharpness when sculptured. The following is the process 

 adopted : The surface of the marble or stone is wetted with a solution 

 composed of tw r o parts of lime and one part of pearlash. The stone is then 

 exposed to a gradual heat until dried, and, when sufficiently hot, white bees- 

 wax is passed quickly over the surface. This should be done two or thrc- 

 times should the marble or stone be very porous ; the surface should then be 

 cleaned while the stone is warm, and afterwards cooled by pouring cold 

 water upon it. Variegated patterns or devices in colors may also be pro- 

 duced by applying them to the surface according to the taste of the artist, 

 and the stone then heated, beeswax rubbed over it, and cooled by water as 

 before. Common stone work may be indurated by dissolving one pound of 

 calcined beeswax in one gallon of coal-tar naphtha, and applying the mix- 



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