MECHANICS AND USEFUL ARTS. 53 



the parts touched with asphalturn, and the latter finally removed with 

 essence of turpentine. 



After the application of every coat of color or varnish, the object 

 so colored or varnished is dried in an oven or chamber, called a stove, 

 and heated by flues to as high a temperature as can safely be em- 

 ployed without injuring the articles, or causing the varnish to blister. 



For black grounds, drop ivory-black mixed with dark-colored 

 anime varnish is used ; for colored grounds, the ordinary painter's 

 colors, ground with linseed oil or turpentine, and mixed with anime 

 varnish. 



The colors are protected against atmospheric influences, and made 

 to shine with greater brilliancy, by two or three coats of copal or 

 anime varnish. Superior articles receive as many as five or six coats 

 of varnish, and are finally polished. 



The ornamentation of all such articles as come under the head of 

 toilet wares is effected by the ordinary mode of painting with the 

 caniel's-hair pencil, or some fitting substitute ; where imitation of 

 woods or marble is intended, the ordinary grainer's tools are used. 

 Many patterns are produced upon the various articles by " transfer- 

 printing." 



Designs in mother-of-pearl are laid on with black varnish, the arti- 

 cle is then varnished all over, dried, then rubbed down over the de- 

 sign with pumice-stone : another coat of varnish is then laid on, dried, 

 and the part covering the design again rubbed off with pumice-stone ; 

 and thus several coats are laid on, until all the surface is level with 

 that of the design. Ornamental lines, writing, etc., are laid on with 

 color. The inlaying with mother-of-pearl is a laborious business, 

 owing to the small size of the pieces at the artist's disposal, and the 

 necessity of attending to a proper distribution and fitting of lights 

 and shades. 



INDIA RUBBER VARNISH. 



That India rubber, dissolved in various liquids, yields a good varnish, 

 is well known ; but in general they are too viscid for delicate pur- 

 poses, and are only good for making stuffs waterproof. India rubber 

 liquefied by heat, dissolved in oil of tar, or drying linseed oil, does not 

 give a varnish of sufficient fluency, or free from smell. Moreover, a 

 considerable quantity of India rubber remains undissolved in a gelatin- 

 ous state, suspended in the liquid, so that the solution is never clear. 

 Dr. Bolley has recently published some remarks on this subject, which 

 may be usefid. If India rubber be cut into small pieces and digested 

 in sulphuret of carbon, a jelly will be formed ; this must be treated 

 with benzine, and thus a much greater proportion of caoutchouc will 

 be dissolved than would be done by any other method. The liquid 

 must be strained through a woollen cloth, and the sulphuret of car- 

 bon be drawn off by evaporation in a water-bath ; after which the 

 remaining liquid may be diluted at will with benzine, by which 

 means a transparent, but still yellowislTliquid, will be obtained. A 

 more colorless solution may be prepared by digesting India rubber 

 cut into small pieces for many days in benzine, and frequently shak- 

 ing the bottle which contains it. The jelly thus formed will partly 



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