Changes in Temperature and Distribution of Magnetism. 273 
THE EFFECTS OF CHANGES IN TEMPERATURE ON 
THE DISTRIBUTION OF MAGNETISM. 
By HIRAM B. LOOMIS, Ph. D., 
Instructor in Physics, State University. 
The following paper is an account of some experiments undertaken to 
determine more accurately, if possible, the kind of change which takes 
place when a magnet is heated and cooled. An extensive investigation 
of the changes in magnetic distribution, moment, and permeability is 
under way and considerable work has been done in all three lines. 
Though the results so far obtained as to changes in moment and perme¬ 
ability are not deemed complete enough for publication, the investiga¬ 
tion as to the changes in distribution may be of interest. 
The subject will be considered under the following heads: 
I. Historical Sketch. 
II. Description of Apparatus and Experiment. 
III. Calculation and Verification of Results. 
IV. Discussion of Results. 
I. HISTORY. 
* About 1825, Kupffer magnetized a steel bar and placed it in a water 
bath. Near it he suspended a magnetic needle and determined the 
period of 300 swings before the temperature of the bar had changed. 
The bath was then heated to 100° C., and the period of 300 swings again 
determined. The bar was alternately heated and cooled between the 
same limits of temperature, and determinations of the period were 
made. His results may be summed up as follows: If a permanent 
magnet be heated above the temperature of magnetization, its magnetic 
moment decreases., On again cooling the moment increases, but not 
enough to make up the first loss. This is true of the first three or four 
heatings and coolings. 
t Riess and Moser also experimented on the change in magnetic moment 
by swinging magnets in the earth’s field and determining the period of 
* Wiedemann’s Electricitat III., p. 753. 
t Riess und Moser, Pogg. Ann. 17, p. 425, 1829. 
18—A. & L. 
