AND RESISTANCE OF NICKEL WIRE AT HIGH TEMPERATURES. AT 
words, the first effect of rise of temperature is to increase the permeability in lower 
fields, probably because of the greater ease with which the molecular groupings 
assume new configurations. But anything which tends to increase permeability must 
tend to increase the effect on resistance. As the magnetization approaches its satura- 
tion value, rise of temperature diminishes the permeability, and rapidly so as the critical 
temperature of 350° is approached ; and very similar is the effect of rise of temperature 
on the change of resistance due to a given field. 
The isodynamic curves indicate the existence of a further peculiarity which declares 
itself at or near the temperature of 180° by a kind of cusp-like peak in the graphs of 
the higher fields. This peculiarity is also well brought out by calculating the differences 
between the resistance changes corresponding to the successive temperatures in the pre- 
ceding table, and dividing these by the change of temperature. These average differ- 
ences per degree will correspond to the mean of the extreme temperatures; and their 
values for five of the fields are given in the following subsidiary Table C. 
TABLE C, 
Showing differences per degree calculated from Table B. 
Magnetic Differences per Degree at Temperatures 
|. ee 95° | 152°5 | 210° 260" 290° 314° | 385° 
34 4°5 3°3 oui 37 2°8 27 | 15 2°9 
28 2-9 2°5 2°3 2°9 2°5 25 | 1-4 2°6 
20 13 15 ey 2°0 Ie 20 =| 13 14 
10 0°01 0°01 0'4 0-9 1:0 Tel | 14 0°2 
6 —9°02 | -0°003 —0°9 0-7 0°45 O4 | 1:0 , 
From these few examples we see that there is at or near the temperature 200° a 
peculiarity which shows itself by an increase in the rate per unit rise of temperature at 
which the resistance change due to a given field is diminishing. 
5. COMPARISON WITH RESULTS FORMERLY OBTAINED.— When we compare the results 
here given with those obtained in the earlier experiments a considerable discrepancy 
declares itself. From the results given in the final table in the earlier paper (Z'rans. 
R.S.H., vol. xl. p. 548), we readily find by interpolation the resistance changes at the 
three temperatures 12°7, 57°5, and 93°5, corresponding to the fields 30, 22, and 14. 
Then, from the table given above (p. 45) we can interpolate values corresponding to 
the same fields and temperatures. These are compared in the following short table (D), 
the earlier and later results being distinguished by the Roman numerals I. and II. 
TRANS. ROY. SOC. EDIN., VOL. XLI. PART I. (NO. 3). 
