AND RESISTANCE OF NICKEL WIRE AT HIGH TEMPERATURES. 45 
ratio to the whole resistance L at all temperatures. It is possible, however, that with 
the strongest currents, whose heating effect is quite apparent in the slight rise and then 
fall of temperature during one set of readings as shown in Table A, the part of the 
nickel wire included within the magnetizing coil might be slightly higher in tempera- 
ture than the short parts outside the coil which joined the nickel wire to the stout 
nickel terminals. This would make the ratio Ly/L a little greater in the highest fields, 
so that the quantity dL/L,) would be a little smaller. It is clear, however, that any 
small error due to this cause will not materially affect the broad conclusions to be 
drawn from the experiments. 
In Table B are given the final reductions, each column corresponding to a particular 
temperature, and each horizontal row to a particular field. The numbers entered are 
the increments of resistance per 100,000 ohms, 
TABLE B. 
Showing resistance changes per 100,000 ohms of nickel wire in 
various longitudinal fields and at various temperatures. 
Resistance Changes at Temperatures 
| Magnetic 
Field. 1° 65° 125° 180° 240° 280° 300° | 328° | 349° 
34 1040 S16 621 475 253 14i 86 45 5 
3 970 776 594. 450 244 138 83 44 
30 901 729 565 426 235 133 81 43 
28 825 679 529 401 226 128 79 4] 4 
26 749 629 498 375 216 123 76 38 
24 682 579 463 350 205 119 73 35 
22 613 529 425 324 193 113 69 32 D) 
20 543 479 399 298 179 106 66 2 
18 474 429 356 270 166 | 100 61 24 sok 
16 411 379 317 242 ier | 93 57 18 1°6 
14 341 318 275 215 |. 135 84 52 12 ee 
12 268 255 931 186 112 75 48 6 
10 192 187 181 158 103 64 49 4 1 
8 119 124 123 121 85 52 37 3 
6 53 63 65 70 56 38 30 2 
4 7 23 21 23 27 27 19 1 
2 3 5 5 5 5:5 5 4 
The numbers in the last column under temperature 342° C. were just measurable ; 
anything under 3 is, in fact, barely outside the errors of observation. 
4, Discussion oF THE RESULTS.—These numbers give two sets of graphs—namely, 
the isothermals showing the relation between magnetizing force and resistance change 
at the various temperatures, and the isodynamics showing the relation between the 
