steel | 29,452 | .00201 |Ni 4.35%, remaining|
| | | | percentage |
| | | | chiefly iron, but|
| | | | uncertain |
|German silver | 29,982 | .000273 |Cu5Zn3Ni2 |
|Platinoid[9] | 41,731 | .00031 | |
|Manganin | 46,678 | .0000 |Cu 84%, Mn 12%, |
| | | |Ni 4% |
|Aluminium-silver | 4,641 | .00238 |Al 94%, Ag 6% |
|Aluminium-copper | 2,904 | .00381 |Al 94%, Cu 6% |
|Copper-aluminium | 8,847 | .000897 |Cu 97%, Al 3% |
|Copper-nickel-aluminium| 14,912 | .000643 |Cu 87%, Ni 6.5%, |
| | | | Al 6.5% |
|Titanium-aluminium | 3,887 | .00290 | |
+-----------------------+-----------+-------------+-------------------+

Generally speaking, an alloy having high resistivity has poor
mechanical qualities, that is to say, its tensile strength and
ductility are small. It is possible to form alloys having a
resistivity as high as 100 microhms per cubic centimetre; but, on the
other hand, the value of an alloy for electro-technical purposes is
judged not merely by its resistivity, but also by the degree to which
its resistivity varies with temperature, and by its capability of
being easily drawn into fine wire of not very small tensile strength.
Some pure metals when alloyed with a small proportion of another metal
do not suffer much change in resistivity, but in other cases the
resultant alloy has a much higher resistivity. Thus an alloy of pure
copper with 3% of aluminium has a resistivity about 5-1/2 times that of
copper; but if pure aluminium is alloyed with 6% of copper, the
resistivity of the product is not more than 20% greater than that of
pure aluminium. The presence of a very small proportion of a
non-metallic element in a metallic mass, such as oxygen, sulphur or
phosphorus, has a very great effect in increasing the resistivity.
Certain metallic elements also have the same power; thus platinoid has
a resistivity 30% greater than German silver, though it differs from
it merely in containi