LEAD. By CARL W. MITMAN, Curator, Divisions of Mineral and Mechanical Technology, United States National Museum. [With 6 plates.] The Division of Mineral Technology, a part of the Department of Arts and Industries of the United States National Museum, is engaged in preparing exhibits designed to enhance the popular conception of the many mineral resource industries, their technology, economics and general social bearing. With the cooperation of active producers there have been obtained series of models, photographs, drawings, and raw and finished products which by their arrangement, set forth for many of the important minerals, the condition of their occurrence; the operations followed for their extraction; the processes of manufacture; the nature of the products and their adaptability to use. Unfortunately, the opportunity of visiting the National Museum is not had by everyone and the present article is prepared, therefore, to disseminate in story form the salient features observed in the exhibit devoted to the lead industry. GENERAL CONSIDERATIONS. The uses of lead in the things of everyday life are almost without end. It is present in the home, in paint, in glassware, china, and pottery, and in the piano; in the church, in the pipe organ, and stained-glass windows; in the office, in the typewriter, in the windowpanes, and window-sash weights; in the factory, in the bearings of all revolving machinery; in the automobile, in its engine bearings, tires, and even its license tag; in ships, airplanes, and locomotives. Without it the printing of newspapers, books, and magazines would be seriously hindered; madame would have difficulty in obtaining the right "hang" to her costume and duck hunting would be out of the question altogether. Considering these random uses, together with the fact that there is an automobile available for every 10 inhabitants in the United States; that every progressive community in the country has its annual “Clean-Up-Paint-Up Week"; and that even the village church has its pipe organ; the thought immediately occurs that surely there is no other metal as useful as lead. As a matter of fact, however, if the quantities annually consumed are taken as an indication, lead is outranked in usefulness by iron and steel and copper, but in diversity of utility only by iron and steel. The benefits enjoyed by the millions of people in this country through the use of lead and its compounds are made possible through the efforts of some 60,000 individuals engaged in the lead industry. and an endeavor is made in the pages following to tell briefly of their work. There is a leaden figure in the British Museum which was taken from the Temple of Osiris, at Abydos, one of the most ancient cities of Upper Egypt. The temple is believed to have been built prior to 3800 B. C., so that the leaden figure is approximately 5,700 years old. This is the only evidence of the early use of lead until several thousand years later, but inasmuch as lead is so closely allied in nature with silver and is a necessary factor in the production of silver, the inference may be drawn that lead was known prior to any direct evidence of the metal. Thus, the earliest known Egyptian silver is believed to be a string of beads of the period of the twelfth dynasty, 2400 B. C. There are records to show that lead was reduced from its ores by smelting prior to 2000 B. C.; lead was amongst the spoils captured by Thothmes III in 1500 B. C.; and white lead was made by corroding metallic lead with vinegar about 300 B. C. Strabo, about the beginning of the Christian era, mentions the use of high stacks to carry off lead fumes, which statement would imply that progress had been made in the metallurgy of lead and that furnaces equipped with bellows had replaced the crude hearth. Again, there are a number of old Roman lead weights for balance scales in the National Museum at Washington dating from early in the Christian era, and the instances of the unearthing of ancient lead water pipes in various parts of Europe are numerous. While facts to visualize still further the history of lead since the Christian era might be presented, the evidence already given indicates the gradual increase in importance of lead and therefore the gradual development of a lead industry. At the beginning of the nineteenth century the bulk of the world's lead came from England and Spain, the industry in each of these countries having been started by the Romans; England supplied two-thirds annually and Spain one-third. Germany, Austria, Hungary, France, Russia, and the United States began to rank as pro ducers about 1820; Belgium entered the field in 1840; Italy in 1860; Mexico, Canada, Japan, and Greece in 1880; and Australia joined in 1888. This order in the ranks of the world's producers remained practically unchanged until 1870, when the United States displaced England for first honors, and has maintained this position ever since, producing at present over one-third of the world's supply. For a true picture of the development of the lead industry in the United States, it is only necessary to consider the development of the country. The first settlements were made in the East, and there a lead industry was started even before that of any other metal, for protection was a necessity and lead shot was a decisive means to this end. As a result, lead ores were sought, mined, and smelted in many of the original 13 Colonies. Coincident with westward migration, lead was discovered in the Middle West and later in the Far FIG. 1.-Production of lead in the United States and the rest of the world since 1860. Data from United States Geological Survey and Mineral Industry. West and in such vast quantities that when once transportation facilities became available (about 1870) the deposits of the East, except those of Virginia, were abandoned. The story is visualized graphically in figure 2. The outstanding feature of this growth is that it is essentially the result of domestic cultivation. There was a time between 1840 and 1850 when the demand for lead was less than the production and the excess of lead was exported; again during the restless times preceding and following the Civil War the demand exceeded the production so that lead had to be imported; and finally, to meet the demands of the Allies during the World War, the production of lead increased, even above the abnormal domestic demand, and this excess was exported. But, other than this, the lead output of the United States is used at home. As a matter of fact, the periods of home consumption and exporting of lead, as shown in figure 3, rep 101257-22--39 resent very closely the general growth of most of the metal industries in this country, date for date, and period for period. LEAD ORES: TYPES AND DISTRIBUTION. The mineral galena, a compound of lead and sulphur, is the important constituent of the majority of lead ores. It occurs in groups of cubical crystals which are "as heavy as lead" and whose faces have the appearance both in color and luster of highly polished steel. Some lead is derived from ores containing the minerals cerusite and anglesite, formed by the oxidation of galena. They, too, are "as heavy as lead" but are not metallic in appearance. When these minerals occur concentrated in rock in quantities sufficient to make the extraction of their lead content profitable, they FIG. 2.-Development of the lead Industry in the United States. Data from United States Geological Survey. constitute true lead ores. In the whole of the United States there is only one section where such ores are found and mined, namely, southeastern Missouri, mainly within St. Francis, Washington, and Madison Counties. A more widespread mode of occurrence of the lead minerals is that in which they are mechanically combined with the minerals of other metals, and while the extraction of the lead alone in such ores would not be profitable, the extraction of all the metals in the combination is profitable, one metal aiding another. Quite a number of such mineral associations of lead and other metals exist, but four only may be said to constitute the major sources from which the country's lead supply is derived. They are found and exploited in many of the Rocky Mountain States and yield approximately two-thirds of the lead used annually, while the true lead ores of southeastern Missouri yield one-third. In summary, therefore, the country's lead supply may be considered as being obtained from five kinds of ores, as listed in the accompanying table, while the mining districts exploiting them are scattered in many of the States west of the Mississippi River, as noted in the map (fig. 4). Sources of lead. FIG. 3.-Growth of the lead industry in the United States. Data from Mineral Industry and United States Geologicla Survey. The presence of silver in every type of ore is due to the fact that practically all galena contains silver in chemical combination with the lead. Zinc, copper, and gold, on the other hand, are derived from minerals physically combined with galena. In addition to the lead obtained direct from ores, a considerable amount is recovered annually from secondary sources, such as scrap pipe, cable coverings, storage-battery lead, and sheet lead. Remelted scrap often contains impurities, such as antimony and tin, and is not ordinarily substituted for lead direct from ores unless its origin and uniformity is proven. A striking illustration of certain stages of development experienced by the lead industry which are constantly recurring, is con |