3i8 JOSEPH STRUTHERS 



brown, and sepia. Blacks: Lampblack, ivory black, bone- 

 black, and graphite. 



The iron oxide pigments are used to make dark red or 

 brown paints, being known in the trade as natural reds. 

 They are classed as natural and artificial, the former (me- 

 tallic paints and mortar color) being chiefly made from 

 brown iron ore and ferruginous shales, and the latter (Ve- 

 netian red, Tuscan red, and Indian red) from calcining 

 copperas or copper residues in a furnace yielding ferric 

 oxide (FeaOs) in a state of very fine division. 



Although the occurrence of iron ores in the United States 

 is widespread, and enormous deposits exist at many places, 

 there are very few localities in which the material is of suit- 

 able physical and chemical composition for manufacture into 

 metallic paint. 



The ores reported for use in the manufacture of metallic 

 paint and mineral paint were mined in Anne Arundel and 

 Baltimore counties, Md.; Carbon county. Pa.; James county, 

 Tenn.; Rutland county, Vt.; Bedford county, Va.; and 

 Dodge county. Wis. The mortar colors were all reported 

 from Northampton county. Pa. Other iron pigments re- 

 ported were mined in Cattaraugus county, N. Y., and Car- 

 bon and Wyoming counties. Pa. The Venetian red reported 

 was all mined in Anne Arundel county, Maryland. 



The iron oxide paints are highly esteemed for some pur- 

 poses on account of their freedom from poisonous ingredi- 

 ents which are found in some mineral paints, and because 

 they resist to a marked degree the effects of light, heat, 

 and moisture, a quality which renders them of great value 

 for outside or exposed work. Ochers in addition resist the 

 destructive action of salt air, and are therefore of special 

 value in localities at or near the seacoast. 



A certain proportion of metallic paint is used as a color- 

 ing matter in mortar making, and appears in some classi- 

 fications under the title mortar colors. 



The mining and preparation of the crude ore for the 

 market are very simple processes. The ore, generally ob- 

 tained by open cut or quarrying methods, is disintegrated by 

 exposure to the atmosphere, carried to a mill, roughly crushed, 



