542 
PROFESSOR J. A. EWING ON EXPERIMENTAL 
cycle to annealed iron. In this a much stronger magnetising force was used than 
before. The wire was a piece nearly the same as that of the last experiment, 
diameter 0'078 centim., length 29'3 centims., or nearly 400 diameters. The observa¬ 
tions (which were made by the direct magnetometric method) are given in a reduced 
form below, and are also exhibited in Plate 58, fig. 6. 
Annealed Iron Wire, Plate 58, fig. 6. 
SB. 
/*• 
95. 
95. 
0 
800 
(initial) 
2-8 
4,830 
1725 
- 4-35 
- 6,300 
47 
11,130 
37 
7,510 
2030 
- 7-8 
-11,540 
7-1 
11,940 
4-8 
9,520 
1980 
-15-5 
-14,360 
11-7 
13,690 
62 
11,130 
1795 
— 46 - 6 
-15,200 
15-5 
14,360 
7-8 
12,340 
1580 
-89-8 
-16,040 
23-3 
14,770 
9-3 
13,140 
1410 
-26.7 
-14,910 
38-8 
15,590 
10-9 
13,550 
1240 
-19-5 
-14,630 
66-8 
16,160 
14 6 
14,220 
970 
-15-5 
-14,490 
89-8 
16,310 
23-3 
14,900 
640 
-11-2 
-14,360 
311 
15,180 
490 
- 7-9 
-14,080 
46-6 
15,700 
340 
- 6-2 
-13,950 
69.9 
16,160 
230 
- 4-6 
-13,680 
89'8 
16,450 
183 
- 4-0 
-13,410 
0 
12.740 
0 
-12,070 
15-5 
14,760 
1-5 
- 8,580 
31-0 
15,310 
2-4 
- 2,680 
62-1 
16,010 
2-9 
670 
89-9 
16,450 
3-1 
1,880 
62-1 
16,150 
36 
4,020 
31-0 
15,480 
37 
4,830 
233 
15,310 
4-3 
6,970 
15-5 
15,030 
4-8 
8,320 
10'9 
14,890 
51 
8,850 
7-8 
14,620 
5-4 
9,390 
4-7 
14,480 
7-1* 
12,080 
0 
12,740 
GO. 
11,940 
4'6 
11,800 
2-5 
11,400 
0 
10,460 
§ 23. Characteristics of the Curve of Magnetisation. —The examples which have 
been cited exhibit very clearly the behaviour of annealed iron when subjected to 
magnetising forces without mechanical disturbance. It matters little whether 
the changes of magnetising force are caused to occur suddenly or gradually : there are 
slight differences in the two cases which will be discussed later, but the general form 
of the curve is scarcely changed. A comparison of rhe figures already given will 
show that the curve of first magnetisation has the following characteristics. At first 
the magnetisation takes place very gradually with respect to the increment of <§,—how 
gradually these experiments do not enable me to say, but the appearance of the 
* A small loop was formed liere by reducing £> from 7‘1 to zero, and reapplying it. See tlie figure. 
