SCIENCE IN THE INDUSTRIAL WORLD 



which cost so much that there is constant temptation 

 for dishonest manufacturers to adulterate them. Most 

 of these adulterants are combinations of lead and iron 

 pigments, some of which give a color closely simulating 

 true mercury vermilion, but all of them lack the per- 

 manency and fineness of shade of the more expensive 

 pigments. 



A close rival of the mercury vermilion, in the matters 

 of shade and permanency, is antimony vermilion, which 

 is a trisulphide of antimony. Commercially, however, 

 it cannot be considered a great rival, although it seems 

 to have many qualities that would entitle it to such a 

 place were it not for the established prejudice in favor 

 of the older pigment. It is much less expensive than 

 true vermilion, and this advantage seems to be gradually 

 bringing it into favor with practical painters. 



For several reasons the ferric-oxide reds, which are 

 sold in the market under such names as Venetian red, 

 Indian red, scarlet red, purple oxide, rouge, and several 

 other less general names, are favorite pigments with 

 painters. They are relatively cheap, permanent under 

 all conditions, and when mixed with other pigments 

 for the most part do not affect them and are not affected 

 by them. They are found in a natural state, sometimes 

 so pure and of such quality that the mineral may be 

 powdered and used as a pigment without further treat- 

 ment. This is not usually the case, however, and most 

 of these pigments are manufactured artificially by one 

 of the many processes known to chemist and paint- 

 manufacturer. 



Another red pigment that is a great favorite for many 

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