Lead
Ores of lead occur in great abundance in almost all parts of the world. They are generally in veins, sometimes in siliceous rocks, sometimes in calcareous rocks. Abundant scripture testimony proves the existence of this metal in olden times, and we are informed that the Romans used sheet-lead in the manufacture of water-pipes. The metal is very heavy but soft, is of a bluish-gray color, of great brilliancy. The specific gravity of lead is 11.35, and it melts at 617 deg. Almost all the lead of commerce is obtained from galena (sulphide of lead). It is then pickled, broken, and washed, and afterwards roasted, to eliminate the sulphur. Lead is an important metal in the arts. Rolled into sheets it is used for roofing houses, for cisterns and pipes. It is also of great service in the construction of large chambers for the manufacture of sulphuric acid; its value for making shot is well known. Lead enters into many very useful alloys, as with bismuth for fusible alloys, with antimony for type-metal, with arsenic for shot, with tin for pewter and solders, with copper for pot-metal--for which compound it cannot be used more than one half lead, as it separates in cooling. With zinc it will scarcely unite, but their union may be brought about by a small proportion of arsenic. Many of the numerous alloys for mechanical and other purposes are improved by certain proportions of lead, and very few mixtures but may be made more fusible, malleable, and sharper in the cast by a slight addition of this metal; but with gold it forms an alloy of extreme brittleness; 1/4 of a grain of lead will render an ounce of gold perfectly brittle, although both gold and lead are such soft and ductile metals. The ductility of copper at any temperature is impaired by the use of lead. Alloyed with silver, the metals will separate if slowly cooled from the melting point. It does not appear that cast iron and lead alloys will answer any useful purpose. Of the compounds of lead other than alloys we have white-lead or carbonate of lead, and red-lead or red oxide of lead, the latter being much used in the manufacture of flint-glass and porcelain.
The various alloys of which lead forms a component part will be found under the following heads: FUSIBLE ALLOYS; TYPE-METAL; LEAD-SHOT; PEWTER; SOLDER; POT-METAL; BISMUTH; ANTIMONY; ARSENIC; TIN; COPPER; ALLOYS; BRASS; ANTI-FRICTION METALS; WHITE-LEAD; RED-LEAD.