118 Barrerr, Brown & Haprirtp—On the Electrical Conductivity and 
It is instructive to note the difference in this respect between the specimens 
1178 E and1179 B. When the amounts of chromium and aluminium are nearly 
reversed, the hardness of the latter specimen is seen in its high coercive force and 
low permeability. By comparing 1167 D, Table XI., with 1178 B, Table XII., 
we see that the addition of 1°75 per cent. of chromium to a low aluminium steel 
more than doubles the hysteresis loss, whilst the coercive force is increased three 
times. The large amount of aluminium in 1178 E lowers the coercive force, and 
hence much reduces the hysteresis loss of this specimen. 
The addition of small percentages of copper does not seem to have much effect 
on the magnetic properties of steel as is seen by comparing 1264 A and B in the 
next Table, which are similar steels, except that 1264 B has about 1 per cent. more 
copper. 
Taste XIII.—Copper Steels. 
Marks. etoe oO eae ey Retentivity. Coercive force. 
Iron 0-0 17480 TIO | 1:66 
1264 A 1°59 15010 | 10840 | 5:0 
» 2:5 14860 | 10740 | 5:4 
#12963 C 2°87 15160 | 9810 5:3 
The large coercive force of these copper steels may be due to the high carbon or 
manganese they contain, as will be seen by referring to the full analysis given in 
Group 8. Another steel containing 145 per cent. of copper with manganese and 
chromium is givenin Table XV. The B and H curves of these copper steels have 
not been engraved, and it also seemed hardly worth while to determine their 
hysteresis loss. 
Passing on to the effect produced by Chromium on the magnetic properties of 
iron, we have examined two specimens of chromium steel, besides several other 
chromium steels, containing nickel or tungsten in addition to chromium. ‘The 
percentage composition of these and other steels is given in the next table. 
A nickel chromium steel, 1450, has already been given in Table VIII., p. 114; 
comparing this with 1447 A and B (see p. 110), which have the same quantity 
of nickel but no chromium, we find all three barely magnetic in a field of 45, in 
the unannealed state, but magnetic in a field of 300, the induction of 1447 being 
twice that of 1450, showing the effect of chromium. 
* This specimen has also 1 per cent. of manganese. 
