PAINTING. 263 



largely found in Africa, South America, New Zealand, and the 

 East Indies. The general process of varnish manufacture is 

 the heating, in a suitable receptacle, of the resins to from 600 

 to 800 degrees F., at which point the resins melt, being de- 

 composed by the heat. 



At this point, hot linseed-oil is added, and the contents 

 stirred until fully combined ; after cooling, the mixture is 

 dissolved or diluted with spirits of turpentine, to permit the 

 proper flow of the varnish under the brush. The greater 

 amount of oil used, the greater the elasticity, tenacity,- and 

 toughness, and the less brittleness, which are desirable quali- 

 ties where the varnish coat is subject to mechanical injury. 

 In addition to the vegetable resins, a " mineral resin," as it 

 has been called, or asphaltum, is often used. Its oil, by dry 

 distillation, is of a yellow color, and said to resemble closely 

 the oil of amber. Used in considerable quantities in the manu- 

 facture of varnish, it exhibits remarkable non-drying qualities, 

 but its compensating advantages are its cheapness, elasticity, 

 tenacity, durability, and insolubility. 



Prof. Sabin gives the following why varnish is better 

 than oil: "The reason why varnish is better than oil is 

 that it is more durable, smoother, and more brilliant, and 

 because the resin dissolving in the oil makes it harder; it 

 makes a film that is harder, and still retains a high degree of 

 elasticity not somuch elasticity, perhaps, as theoriginal alone, 

 but a very high degree of elasticity; and it is very much more 

 impervious to moisture than oil." 



From a paper read June, 1895, by Prof. A. H. Sabin, be- 

 fore the American Society of Civil Engineers, the following 

 is quoted : 



" It has long been known to varnish-makers that the fossil 

 resins known as copals, such as the New Zealand kauri, when 

 added to asphalt-varnishes, improve their durability. This 

 is probably partly owing to the fact that such compounds are 



