STEEL HARDENING METALS i8i 



for coloring porcelain and in the manufacture of artificial 

 teeth. The titanium oxide will, under favorable conditions, 

 impart a fine yellow color to the porcelain, and it is also capable 

 of being used with other substances to produce secondary- 

 colors. The amount of titanium oxide used in the manufac- 

 ture of artificial teeth is from five tenths of 1 per cent to 2 

 per cent of the total materials used in making them. 



At the present time no titanium is used commercially, 

 as far as known, in the manufacture of titanium steel, although 

 irons have been made containing a considerable percentage 

 of titanium, the result of using ores for their iron contents 

 rather than their titanium. Considerable w^ork has been 

 done, however, experimentally in regard to the use and value 

 of titanium steel and with a great deal of success. It is prob- 

 able that the introduction of this kind of steel into the gen- 

 eral market is not far distant. Its properties of special interest 

 are elasticity, and greater elongation and ductility than ordi- 

 nary carbon steel. 



Uranium and vanadium have been mined in small quan- 

 tities for a great many years, some of the salts of uranium 

 being used to produce a pure black glaze on porcelain, while 

 other salts are used in the decoration of glass and china ware, 

 giving permanent colors. Vanadium salts are used in the 

 colormg of glass, but principally in the preparation of vanadic 

 acid, as a mordant, for aniline black in dyeing. The use of 

 uranium and vanadium in the manufacture of special steels 

 is still in the experimental stage, but enough has been done 

 to prove that they increase tensile strength. 



