i8o JOSEPH HYDE PRATT 



by the Pennsylvania Railroad company, and evidently gave 

 entire satisfacton. 



Cobalt is put on the market as the oxide and used almost 

 entirely for coloring glass, porcelain, and similar substances. 



The mining of tungsten and molybdenum ores in the 

 United States has become an established industry within 

 the past few years only. Tungsten ores were mined in Colo- 

 rado and Connecticut, and molybdenum ores in Washington. 



Until lately the uses of these metals were few, requiring 

 a comparatively small amount of their salts to satisfy the 

 demand. The salts of tungsten were used as a mordant 

 in dyeing and printing and as fireproof material for wearing 

 apparel, while the principal use of molybdenum was in the 

 manufacture of ammonium molybdate, used by chemists 

 in the determination of phosphoric acid. A small amount 

 of molybdenum salts is used in the preparation of blue carmine 

 or molybdenum blue in the coloring of porcelain. The use, 

 however, of these two metals in the preparation of ferro alloys 

 has led to an increased demand, especially for tungsten, which 

 when added to steel, increases its hardness and toughness, 

 and is believed by some to make it superior for certain pur- 

 poses to any other manufactured. Tungsten steel is also 

 used in the manufacture of tool steel, spring steel, and sound- 

 ing plates and wire for pianos, where hardness and strength 

 are especially desired. Molybdenum steel, the beneficial 

 properties of which are similar to those of tungsten, is begin- 

 ning to be used, but in much smaller quantity. 



The only titanium mineral mined for commercial pur- 

 poses is rutile, a titanium oxide. Titanium was formerly 

 considered one of the very rare metals, but it has now been 

 proved to be one of the commoner elements and is very widely 

 distributed. In the future, besides rutile, the chief com- 

 mercial source of titanium will be the mineral menaccanite 

 (ilmenite), a titanium iron oxide. Rutile has been produced 

 at Roseland, Nelson county, Va., and in Chester county. 

 Pa. Only a small quantity is required to satisfy the demand, 

 and the product does not amount to much over 100 tons 

 of the crude ore per year. 



The uses of rutile are principally in the ceramic industry 



