SCIENCE IN THE INDUSTRIAL WORLD 



importance to both. But even substances of purely 

 organic nature, when used as pigments are usually 

 combined with some metallic substance. Thus, the 

 important class of pigments known as the "lakes" are 

 compounds of an organic coloring-principle with a 

 metallic body. 



The lakes seem to derive their name from the ancient 

 Italian dyers, who called the colored scum which rose to 

 the surface of their dye- vats, lacca. This they gathered 

 and sold to artists as a pigment, which came to be known 

 eventually as "lake" pigment. 



Until recent years the organic coloring-principle of the 

 lake pigments was derived from cochineal insects, 

 madder red, Persian berries, Brazil wood, sapan 

 wood, fustic, and several other sources; and these 

 sources continue to be of importance to-day. But the 

 discovery of the products of coal-tar revealed, among 

 other things, that all manner of lake colors could be 

 made from that peculiar substance ; and as a result the 

 animal and vegetable worlds have been largely shorn of 

 their importance as the source of pigments. Indeed, it 

 seems so certain that the pigments from animal and 

 vegetable sources will eventually be replaced by those 

 derived from coal-tar, and similar mineral products, 

 that a description of the method in use to-day of making 

 a vegetable pigment may have only historical impor- 

 tance and interest to-morrow. 



Aside from white pigments, there is no shade or 

 color that cannot be made from the lakes. Some of these 

 are fugitive and of little use as permanent pigments, 

 while others, such as carmine, make the "finest and most 



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