The principal characters by which steel may be distinguished from iron, are as follows:
1. After being polished, steel appears of a whiter light gray hue, without the blue cast exhibited by iron. It also takes a higher polish.
2. The hardest steel, when not annealed, appears granulated, but dull, and without shining fibres.
3. When steeped in acids the harder the steel is, of a darker hue is its surface.
4. Steel is not so much inclined to rust as iron.
5. In general, steel has a greater specific gravity.
6. By being hardened and wrought, it may be rendered much more elastic than iron,
7. It is not attracted so strongly by the magnet as soft iron. It likewise acquires magnetic properties more slowly, but retains them longer; for which reason, steel is used in making needles for compasses and artificial magnets.
8. Steel is ignited sooner, and fuses with less degree of heat than malleable iron, which can scarcely be made to fuse without the addition of powdered charcoal; by which it is converted into steel, and afterwards into crude iron.
9. Polished steel is sooner tinged by heat, and that with higher colors than iron.
10. In a calcining heat, it suffers less loss by burning than soft iron does in the same heat, and the same time. In calcination a light blue flame hovers over the steel, either with or without a sulphurous odor.
11. The scales of steel are harder and sharper than those of iron and consequently more fit for polishing with.
12. In a white heat, when exposed to the blast of the bellows among the coals, it begins to sweat wet, or melt, partly with light-colored and bright and partly with red sparkles, but less crackling than those of iron. In a melting heat, too, it consumes faster.
13. In the sulphuric, nitric, and other acids steel is violently attacked, but is longer in dissolving than iron. After maceration, according as it is softer or harder, it appears of a lighter or darker gray color; while iron on the other hand is white.
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