SCIENCE IN THE INDUSTRIAL WORLD 



Vat dyes, or the fifth group, are difficult to apply, 

 but they include the important dyestuff, indigo. 



The sixth group, or developed dyes, are produced in 

 the fibers from the substances that are not dyestuffs. 

 In this group come the important aniline black, and the 

 colors produced by the combination of naphthols with 

 the diazotized amido compounds. 



The number of these artificial dyes runs into the 

 hundreds, and there are endless methods of applying 

 them. As the composition of many of the colors and 

 the methods of applying them are trade secrets, it is 

 impossible to consider them individually, or to treat 

 the subject in anything but the most general way. 



VAENISHES 



By all means the most important varnish indeed, 

 the only one known to most persons by that name is 

 the commonplace substance used as finishing for furni- 

 ture, vehicles, interiors of houses, and a hundred other 

 every-day things. To be sure there are several other 

 rather common varnishes, such as damar varnish, 

 which is made of a resin dissolved in an essential oil, 

 and spirit varnish, of which shellac varnish is the most 

 familiar example. But the importance of these is 

 insignificant as compared with that of what is familiarly 

 known as "varnish," without any distinguishing ad- 

 jective, and which is a solution of resin in linseed oil, 

 thinned to a certain consistency with turpentine or 

 benzine. 



The process of making varnish constitutes a great 

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