MAGNETISATION OF IRON AND OTHER MAGNETIC METALS. 
235 
It will be noticed that the quantity in the third column, which no doubt approximates 
very closely to the intensity of magnetisation 3; is practically constant, except for 
errors of observation. Its mean value is 1G85. 
§ 27. Another bobbin, described by Messrs. Jowitt as Swedish wrought iron of the 
celebrated (l) brand, the purest and most expensive iron used in commerce, made by 
the Walloon process, was also turned to the shape shown in fig. 11 , and tested as 
follows ;— 
Table VI.—Fine Swedish Iron, © Brand. 
Outside field. 
s. 
3? — outside field 
33 
47r 
outside field 
5,310 
25,670 
1620 
4-83 
17.680 
38,080 
1620 
2T5 
19,240 
39,540 
1620 
2-06 
It would seem that the saturation value of 3 is specifically less in this iron than in 
previous samples. 
Cast Iron. 
§ 28. Table VII., which is copied from our former paper, gives the results of tests 
made with a bobbin of cast iron of a form similar to that shown in fig. 1, the 
magnetisation being measured by reversing the bobbin in the field. The residual 
induction v^as also measured by withdrawing the bobbin, and was found to have a 
nearly constant value of about 400 c.g.s. units. 
Table VII.—Cast Iron. 
Outside field. 
43. 
43 — outside field 
33 
47r 
outside field 
3,900 
19,660 
1250 
5-04 
6,400 
21,930 
1249 
3-42 
7,710 
22,830 
1200 
2-96 
8,080 
23,.520 
1230 
2-91 
9,210 
24,580 
1220 
2-67 
9,700 
24,900 
1210 
2-57 
10,610 
25,600 
1190 
2-46 
§ 29. Table VIII. relates to a later test, made with Professor Tail’s magnet, in 
which a central spindle of cast iron was used to form the neck of the bobbin, but 
the conical ends were of wrought iron shrunk on to the ends of the spindle. Fig. 12 
shows a section of this bobbin. A similar construction has been adopted in many 
2 H 2 
