124 ECONOMIC GEOLOGY 



orange mineral and sublimed blue lead. Lead is used in the manu- 

 facture of lead pipe, shot, etc., and in many alloys that are of great 

 commercial significance. Sheet lead is used extensively for lin- 

 ings to withstand the corrosive action of acids or acid vapors. In 

 the manufacture of sulphurous and sulphuric acid the chambers 

 and towers are lined with sheet lead. Lead is also used for the 

 barrels utilized in the chlorination of gold and for the linings of 

 many vats. In former years sheet lead was used for roofing and 

 for jointing but other metals have largely taken its place. It has 

 been used in the glazing of windows, and now an exceedingly im- 

 portant use is for coverings for electric cables. This use perhaps 

 more than any other is responsible for the increasing domestic 

 consumption. 



Shot was early manufactured in Missouri and Wisconsin. Pos- 

 sibly this is the earliest use of lead in America. In times of peace 

 and war a continuance of that use is very important. Lead is 

 used also in storage batteries and in many forms of chemical works. 

 Among the alloys type metal, britannia ware, and the various 

 form of babbitt known as antifriction alloys are exceedingly im- 

 portant. It is used also in the various grades of solder as fine, 

 medium and coarse; in the composition of organ pipes; in the fus- 

 ible alloys used in electric lighting systems; in fireprotection 

 sprinklers and in alloys with the precious metals, some of which 

 are of commercial significance. 



White lead is the most important of the lead pigments. It is 

 used directly as a pigment and as a source of other pigments. 

 White lead has to meet the competition of zinc white and heavy 

 spar. These three pigments are sometimes used together. Ninety 

 per cent, of all the white lead of commerce is manufactured by 

 the Dutch process at New Kensington, Pa., by the Sterling White 

 Lead Company. Their product is surpassed by none in its opac- 

 ity, its covering power, and in its durability as a pigment. The 

 process is based upon the fact that acetic acid has a strong 

 corrosive effect upon lead. The lead is therefore immersed for 

 several months in dilute acetic acid or vinegar, when in the 

 presence of carbon dioxide and heat the corrosion is complete. 

 The liquid is drawn off. The residue is placed in drying rooms 

 which are of the filter type not used elsewhere in the world. The 

 heat required in drying is small, only enough to remove what 

 moisture cannot pass through the filters. Chestnut and oak 

 bark are used in the process. The bark is exhausted only to its 



