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Full text of "Metallurgy Of Cast Iron"

318                       METALLURGY   OF   CAST   IRON.
not imply that there is a less total loss of iron with stove plate than heavier iron, as we know by actual practice the reverse to be true. The greater loss of iron by remelting stove plate than is found in heavier irons, is due to the films of oxide, or scales of rust and dirt which, when attacked by the high temperatures of a cupola, etc., in blast, either go to make extra slag or escape out of the stack in other forms. This phenomena in extra slag production is exhibited in actual practice whenever we melt dirty or burnt iron, as all founders well know.
The facts presented herewith suggest that opinions of the past in regard to oxidation of metal are in many cases not well founded, and that where losses of iron have been attributed to oxidation of the metallic iron proper, or a reduction of the metalloids, proper account has not been taken of the dirt, rust, or films of oxide that might have covered the surface of the pig or scrap iron used. We are led to conclude that if it were possible for us to secure clean iron, free of all sand, rust or scales, or oxide of iron, the loss of metallic iron due to oxidation proper is not as large as has been generally supposed.
During the discussion of this paper, Mr. Uehling showed the reliability of the author's experiments on oxidation by presenting the following losses (Table 69) calculated from the results given in Table 63, page 311:
TABLE   69.
Sand iron lost.................................................................5-595 per cent average.
Ijme wash loss.............................................................3.765   "       "         "
Graphite wash loss......................................................  3-425   "      "         u the heavier or sandless gray roll iron. While this is shown as such, it doeslate obtained.        .           ,      '    S<> Ibs,	sy Ibs	<jl Ibs	fi Ibs