│ │ │ │ │ │ │ Misc. Castings. │ └──────────┴─┴──────────┴─┴────────────────────┴─┴─────────────────────┘ ┌──────────┬─┬──────────┬─┬────────────────────┬─┬─────────────────────┐ │ │ │ │ │ │ │ Railway Car and │ │ CHARCOAL │ │ │ │ MALLEABLE IRON. │ │ Agricultural │ │35,436,017│↙│ │↘│ 1,000,000 tons │→│ Machinery Castings, │ │ BUSHELS │ │ │ │ (750,000 tons Pig │ │ Pipe Fittings, │ │ │ │ │ │ used). │ │ Miscellaneous │ │ │ │ │ │ │ │ Castings. │ └──────────┴─┴──────────┴─┴────────────────────┴─┴─────────────────────┘ ┌──────────┬─┬──────────┬─┬────────────────────┬─┬─────────────────────┐ │LIMESTONE │ │ │ │ 108 Plants. │ │Tool Steels, Ordnance│ │15,092,166│↙│ │↘│ CRUCIBLE STEEL. │→│Materials, Bar Steel,│ │ TONS │ │ │ │ 121,517 tons. │ │ Castings. │ └──────────┴─┴──────────┴─┴────────────────────┴─┴─────────────────────┘ ┌──────────┬─┬──────────┬─┬────────────────────┬─┬─────────────────────┐ │ │ │ │ │ 14 Plants. │ │ Rails, Bar Steel, │ │ │ │ │↘│ ELECTRIC STEEL. │→│ Castings. │ │ │ │ │ │ 18,309 tons. │ │ │ └──────────┴─┴──────────┴─┴────────────────────┴─┴─────────────────────┘ ┌──────────┬─┬──────────┬─┬────────────────────┬─┬─────────────────────┐ │ │ │ │ │ 4 Plants. │ │ │ │ │ │ │↘│ OTHER STEEL │→│ Tool Steels, Bar │ │ │ │ │ │ PROCESSES. │ │Steel, Miscellaneous.│ │ │ │ │ │ 2853 tons. │ │ │ └──────────┴─┴──────────┴─┴────────────────────┴─┴─────────────────────┘ * Figures for Pig Iron Used are Estimates, no Conclusive Statistics being available. [Illustration: PART OF A CHEMICAL LABORATORY WHERE 6,000 SAMPLES A YEAR ARE ANALYZED ] By cutting in any direction through a piece of metal or alloy, polishing the surface exposed very clean and smooth and then etching (corroding) slightly with acid, the exposed grains of the metal may be seen when sufficiently magnified. Not only may the grains of metal be seen, but certain of the other constituents which are present are visible. Photographs, also, can be taken by attaching a camera to the microscope. This method of analysis, which is known as “metallography,” has proved as valuable an aid to the metallurgist as it proved to the geologist when applied to the study of rocks and geological specimens. [Illustration: MACHINE FOR DETERMINING STRENGTH OF IRON AND STEEL BARS ]