The London, Edinburgh and Dublin philosophical magazine and journal of science . lexion-points in the curve ofvolume-change. With the cast specimen the feature is stillmore different from the other ferromagnetic substances. ? Thediminution of volume takes place quite rapidly in weak fields,so that the curve soon reaches an inflexion-point. The rateof diminution after passing this point is very small, the curvepassing on almost parallel to the axis of the field. This statecontinues for a large range of fields, but the curve, insteadof showing another inflexion-point, reaches a point of maxi-mum
The London, Edinburgh and Dublin philosophical magazine and journal of science . lexion-points in the curve ofvolume-change. With the cast specimen the feature is stillmore different from the other ferromagnetic substances. ? Thediminution of volume takes place quite rapidly in weak fields,so that the curve soon reaches an inflexion-point. The rateof diminution after passing this point is very small, the curvepassing on almost parallel to the axis of the field. This statecontinues for a large range of fields, but the curve, insteadof showing another inflexion-point, reaches a point of maxi-mum diminution of volume. The course of the curve turnsand proceeds in the same direction so far as the present eK-periment goes. This character is possessed by cast cobaltonly among the numerous specimens of ferromagnetic sub-stances hitherto experimented upon. Further, we may noticethat the amount of the change is, to a certain extent, greaterin cobalt than in iron, steel, or nickel. (d) Mckel-Steel (fig. i)). The volume-change in nickel-steel is simple but extremely Fig. 200 400 600 800 1000 1200 1400 1600 2000 large compared to other ferromagnetic substances. Thecommon feature of the change, as will b£ seen from the of Steel, JVickelj Cobalt, and Nickel-Steels. 59 graphical representation, is the approximate proportionalityof the effect to the magnetizing force. The magnitude of the change is, however, not directlyproportional to the intensity of magnetization, as the 46 percent. Ni shows a smaller effect than the 29 per cent. Ni, whichis the least magnetizable among the specimens with theexception of 25 per cent. Ni, whose magnetization is scarcelyto be detected by ordinary means. In fields of 1600 the change amounts to 13 = 3-8 x 10~6 for 46 per cent. Ni. = 22-0 xl0~6 »J 36 7J = 48-9 xlO-6 5? 29 » = 0-2 xlO-6 V 25 ii = 1-2 XlO6 •)> soft iron. The difference between steels containing different per-centages of nickel is indeed remarkable, as the changes
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
