The Iron and steel magazine . , is not sufficient. In gray iron (photograph 14) we find beside free graphiteand pearlite, a few plates of cementite. Consequently thecarbon contained in pearlite and cement it e^must represent forthis case the dissolving capacity of the solidified iron for carbon, * A. Ledebur, Handbuch der Eisenhiittenkunde, fourth edition,p. 310. Tron ( ai Iiii A Hoys [Q5 provided thai with decreasing temperature it is ao1 further di-minished. According to the analysis the quantity of this carbonis equal to the total carbon less the graphite (No. 18) = — = per ce
The Iron and steel magazine . , is not sufficient. In gray iron (photograph 14) we find beside free graphiteand pearlite, a few plates of cementite. Consequently thecarbon contained in pearlite and cement it e^must represent forthis case the dissolving capacity of the solidified iron for carbon, * A. Ledebur, Handbuch der Eisenhiittenkunde, fourth edition,p. 310. Tron ( ai Iiii A Hoys [Q5 provided thai with decreasing temperature it is ao1 further di-minished. According to the analysis the quantity of this carbonis equal to the total carbon less the graphite (No. 18) = — = per cent, which thus for this case would be the max-imum quantity of carbon dissolved in solid iron. If one calcu-lates the same number for No. 5, a white iron of similar composi-tion, we obtain —- = per cent, or a two and one-half1 imos greater solubility in a compound otherwise nearly with the other samples no approximately constant numberfor the maximum quantity of dissolved carbon can be deter-. Fig. 12. Magnified 50 diameters mined. Photograph No. 16 is very instructive, showing a mot-tled iron, that is, a white iron in which areas of gray iron are moreor less regularly scattered through the mass. On account oftheir immediate proximity, the gray and the white places coolwith equal rapidity. Now experience proves that throughslower cooling this iron would have become gray; so we havenow before us an incomplete reaction whose final product isgraphite and whose original constituent is either a solution ofcarbon in iron or cementite. This reaction which begins at themoment of solidification is not ended with the decrease of thetemperature of solidification. The cooling curves show, espe-cially for the gray iron, a delay in the fall of the temperature 196 The Iron and Steel Magazine which takes place not only at 11300 C. but also below this, asign that the reaction begun at the point of solidification, 11300C, continues still further with the loss of
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