PAINTING. 267 



It also seems equally sure that suitable finishing coats 

 should be provided and applied over the priming coat, and 

 that this last film should be of small specific gravity, elastic, 

 impervious to moisture, hard, and tenacious; it should be in- 

 different to sulphurous gases and electrically insulating, all of 

 which properties seem to be fulfilled to a greater degree by 

 an asphaltic varnish than any known varnish or paint compo- 

 sition. On account of its ease of application and quick-dry- 

 ing powers, it is particularly suitable for application upon 

 structures being erected in the open air and exposed to the 

 weather, while the characteristic of a volatile composition to 

 produce a deposition of moisture is of no consequence when 

 that moisture is not formed upon the metal itself, but upon a 

 cement-like coating, which, besides, has a power for decom- 

 posing moisture by the absorption of its oxygen. 



Either paint or varnish coats should, when possible, be 

 put on under the most favorable atmospheric conditions, the 

 best season being during the autumn, when the temperature is 

 apt to remain more uniform, and when fogs and rains are less 

 likely to occur. A suitable interval of time should be ob- 

 served in order that the first coat should be entirely and 

 completely dry before the second coat is added. In order to 

 have the painter or contractor observe this, and to make 

 sure that more than one coat is put on, the several coats 

 should differ slightly in color, so that such neglect would be 

 readily determined and corrected. 



In the purchase of materials, the .preference . should be 

 given old and long-established houses, whose reputation for 

 quality is well known, and it should not be expected that the, 

 purchase of paint materials at less than market prices will be 

 conducive of anything but the practice of adulterating the 

 products. 



In the application of the paints, which should have been 

 selected with considerable care, only experienced and reliable' 



