ON THE magnetic QUALITIES OF IRON. 
1015 
Values of |H dl. 
B. 
IX. 
III. 
VII. 
VIII. 
IV. 
I. 
VI. 
2000 
400 
420 
530 
600 
750 
930 
1100 
3000 
780 
800 
1050 
1150 
1350 
1700 
2150 
4000 
1200 
1260 
1670 
1780 
2030 
2600 
3300 
5000 
1680 
1770 
2440 
2640 
2810 
3800 
4700 
6000 
2200 
2370 
3170 
3360 
3700 
5200 
6200 
7000 
2800 
3150 
4020 
4300 
4650 
6600 
7800 
8000 
3430 
3940 
5020 
5300 
5770 
8400 
9500 
9000 
4160 
4800 
6100 
6380 
6970 
10100 
11400 
10000 
4920 
5730 
7200 
7520 
8340 
11800 
1.3400 
11000 
5800 
6800 
8410 
8750 
9880 
13600 
15600 
12000 
6700 
8000 
9750 
10070 
11550 
15400 
13000 
7620 
9200 
11200 
11460 
13260 
17300 
14000 ; 
8620 
10500 
12780 
13100 
15180 
15000 
9730 
12150 
14600 
14900 
17300 
The values for Ring V. are nearly the same as for Ring III. 
IX. Very soft iron wire (Japanese tests). 
III. Sheet iron, 1’95 millim. thick. 
V. Thin sheet iron, 0‘367 millim. thick. 
VII. Iron wire, 0'975 millim. diameter. 
VIII. Iron wire (of “ Hedgehog ” transformers), 0'602 millim. diameter. 
IV. Thin sheet iron, 0*47 millim. thick. 
I. Fine iron wire, 0’2475 millim. diameter. 
VI. Fine wire, 0‘34 millim. diameter. Supplied as Swedish charcoal iron. 
Again, fig. 22 shows the relation of B to H for the various rings. The values of 
B are the limiting values in the successive cycles, and are measured, as we have 
already pointed out, after the corresponding magnetic force has been many times 
reversed. They are consequently rather lower, especially in the early parts of the 
curve, than those values of B which a first application of H would produce. Comparing 
the curves of fig. 22 we see that high maximum permeability does not necessarily 
imply small hysteresis losses. Ring VIII. with its “ square-shouldered ” curve has a 
higher maximum of permeability than any of the other rings, though its hysteresis 
losses are much greater than those of Rings III. and V. And Rings III. and V. 
differ decidedly in permeability though their hysteresis losses are as nearly as 
possible equal. A reference back to fig. 15 will show that the curves exhibiting 
magnetic cycles may assume a sloping form, implying comparatively little per¬ 
meability, and yet enclose but small areas. Whei] iron is spoken of as magnetically 
soft the implication sometimes is that its permeability is high, sometimes that its 
hysteresis losses are small. The two characteristics are however, in great measure. 
