. Contributions. ayers would persist after that of the softerinterior had disappeared and hence that the resultant magnetic momentwould be reversed at the high temperature. The authors previously mentioned also studied the effect of a rise oftemperature upon a specimen that had been first magnetized stronglyand then subjected to a demagnetizing field just strong enough to leavethe specimen apparently demagnetized. They stated that under theseconditions the negative magnetism that developed with rise of tempera-ture was much stronger than in the other cases and that it occurredafter a very slig
. Contributions. ayers would persist after that of the softerinterior had disappeared and hence that the resultant magnetic momentwould be reversed at the high temperature. The authors previously mentioned also studied the effect of a rise oftemperature upon a specimen that had been first magnetized stronglyand then subjected to a demagnetizing field just strong enough to leavethe specimen apparently demagnetized. They stated that under theseconditions the negative magnetism that developed with rise of tempera-ture was much stronger than in the other cases and that it occurredafter a very slight rise of positive magnetism. The author has beenunable to reproduce these results. What has happened in each case is arise of positive magnetism, i. e., a flux in the direction of the originalstrong magnetizing field and whether the flux finally reverses at 190° isagain by the method of magnetizing and demagnetizing thespecimen. Fig. 3 shows the results when the specimen was first highly magnetized. Fig. 3. then demagnetized; in both cases the steel being removed from thecoil before the switch was opened thus avoiding entirely the efifccts ofoscillatory currents. With rise of temperature the positive magnetismdevelops, reaches a maximum at about 80°, then decreases reaching zeroat about 200°. On cooling, the steel recovers over 80 per cent, of itsmaximum flux. There is no indication of a reversal. Two other cases naturally suggest themselves: (a) The specimenmight be magnetized and the circuit broken at the switch, then demag-netized without breaking the circuit. We should expect then a reversalof magnetism at high temperatures, (b) The specimen might be mag-netized and removed from the coil without breaking the circuit, thensubjected to a demagnetizing field, the circuit being opened at the switchin the latter operation. The effect of the oscillating current would be toreverse the outer layer with respect to the final field, i. e., to magnetizeit in the direct
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Keywords: ., bookcentury1900, bookdecade1910, bookidcontribution, bookyear1915
