ON A THEORY CONCERNING THE SUDDEN LOSS OF MAGNETIC PROPERTIES OF IRON AND NICKEL.

By Mr. H. Tomlinson, B.A.

Experiments by himself and other observers have shown that the temperatures at which iron and nickel lose their magnetic properties depend on the specimens used and the magnetizing forces employed; but the temperatures at which they begin to lose these properties are definite—for nickel about 300° C., and iron about 680° C. The author's own experiments on "Recalescence of Iron" show two critical temperatures; and Pinchon has shown by calorimetric measurement that between 660° and 720° C., and between 1,000° and 1,050° C., heat becomes latent. All these facts seem to indicate a molecular rearrangement about these temperatures.

In his proposed theory he assumes that the molecules

Prof. Ayrton asked whether the author had made experiments on the reappearance of magnetic properties when raised to a white heat, and Prof. Thompson inquired whether cobalt had been tested. Both questions were answered negatively.