GOG ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



THE MANUFACTURE OF LEAD PRODUCTS. 



An industry comes into existence as a result of the usefulness of 

 a commodity, which usefulness, in turn, is due to the chemical and 

 physical properties possessed by the commodity. It is logical, there- 

 fore, to review the properties and uses of lead before describing the 

 manufacture of lead products. 



PROPERTIES AND USES OF LEAD. 

 1. DENSITY. 



This is probably the most apparent and surely the best known 

 property of lead — a handful of lead being about as heavy as a 

 shovelful of coal and equal in weight to two handfuls of aluminum. 

 Because of this excessive weight in small bulk the use of lead for 

 window-sash weights is extensive; every piano key has a lead 

 counterweight which brings the key back to rest after being struck ; 

 and small-bore firearm and shotgun ammunition is made exclusively 

 of lead primarily because its weight counteracts more effectively the 

 resistance of the air. 



2. HAEDNESS. 



In the " scratch hardness " scale of metals lead is the unit, being 

 the most soft. It is easily marked with the finger nail and will 

 make a mark on paper. There are no uses for lead based solely upon 

 its hardness, but its value as a bearing metal is due in part to this 

 property. 



3. MALLEABILITY, DUCTILITY, AND ANTIFRICTION ABILITY. 



Because lead is malleable and ductile it can be made easily into 

 sheet, pipe, bar, wire, etc. Its malleability is also made use of in 

 packing and calking. Because of its plastic nature lead in the form 

 of pipes and sheets can readily be bent as desired. 



The natural physical properties of lead are quite limited, but 

 science has revealed the fact that by combining two or more metals 

 the resultant product may have properties and uses distinct from 

 those possessed by the individual metals contained in the combina- 

 tion. Such combinations of metals are called " alloys " and may be 

 defined as mixtures of two or more metals which were completely 

 dissolved or miscible at the temperature at which they were mixed. 

 Lead is quite adaptable to such combining and the manufacture of 

 lead alloys has greatly enlarged the field of usefulness of the metal. 



Thus the perquisites for a type metal are low melting point, the 

 taking of a sharp impression of a mold, and being sufficiently tough 

 so as not to lose its shape and at the same time not cut the paper. 

 Lead fulfills the first two of these requirement, but is too soft for 

 the third. By alloying it with antimony and tin, however, the 



