92 
Proceedings of the Royal Society of Edinburgh. [Sess. 
exposure to heat, such as we have in true annealing, results in a very rapid 
growth of hysteresis. It is also evidence of the same fact, that after this 
normalising the alloys exhibit great regularity of magnetic properties. 
The process has therefore resulted merely in removing internal strains and 
differences due to slight variation of conditions during alloying and casting. 
The alloys were normalised by heating to a temperature of about 180° C., 
that being found by trial to be the most suitable. The results of the 
magnetic tests performed after the normalising are given in Table IV. It 
Table IY.— The Normalised Alloys. 
Alloy. 
Test. 
14 per cent. 
16 per cent. 
18 per cent. 
30 per cent. 
38 per cent. 
48 per cent. 
tin. 
tin. 
tin. 
tin. 
tin. 
tin. 
1-20 
18 
28 
24 
? 
22 
2 
ho 
36 
55 
52 
? 
54 
0-5 
boo 
55 
77 
82 
? 
96 
1-0 
1-200 
72 
96 
117 
0-8 
160 
2-0 
1-300 
80 
105 
129 
1*2 
209 
3*0 
I r 
21 
16 
18 
2 
11 
0*5 
C.F. 
22 
10 
14 
2 
9 
ca. 40 
will be observed that the first three alloys — those which are poor in tin — 
have been decidedly improved by the treatment. The increase in the satu- 
ration value of I is very large in the case of the 18 per cent, tin alloy. The 
tin rich alloys are little affected. Indeed the 38 per cent, alloy — as will be 
seen from a comparison of the various tests described in this paper — retains 
its magnetic properties practically unchanged under widely different con- 
ditions. Fig. 1 shows how the normalised 38 per cent, tin alloy — the most 
magnetic of those tested — compares with other magnetic materials. The 
four comparison curves are those obtained in the case of cast iron, cobalt, 
nickel, and the Heusler alloy. It will be at once observed that the copper- 
manganese-tin alloy does not show distinctly the characteristic shape which 
one associates with the majority of ferromagnetic substances. In this alloy 
the susceptibility does not vary so markedly with the field intensity as it 
does in the case of iron, nickel, or the Heusler alloy. There is even an in- 
dication that under the action of very strong magnetising force the intensity 
of magnetisation might exceed that of the Heusler alloy. This, however, 
is a feature only of the 38 per cent, tin alloy and the very feebly magnetic 
30 and 48 per cent, tin alloys. The alloys with a tin content of 14, 16, and 
18 per cent, all show saturation phenomenon. This is illustrated in fig. 2, 
