Numbering Pig Iron
The numbers given to pig iron, as No. 1, No. 2, No. 3, etc., is simply a commercial classification in order to distinguish the various qualities as delivered from the blast-furnaces, indicating to the purchaser the grade or quality of each brand and the purposes for which they are best adapted. No. 1 invariably shows the largest crystals, is soft and bright, and adapted for light castings; No. 2, of the same brand, will be recognized as lighter in color, with smaller crystals, suitable for general work, machinery, etc.; while again, of the same brand we may have a more dense iron, with indications of mottle, which is denominated No. 3; and so on to white iron, a higher number still. See CAST IRON, WHITE IRON, GRAY IRON, MOTTLED IRON.
Number of Nails in a Pound.--See NAILS.