SILICON.
The dividing line between silicon-treated steels and silicon-alloy steels is not clearly defined, but the latter are used for several important purposes.
Such steel has been used in springs of the leaf type for automobiles and other vehicles, the silicon being considered to add slightly to the toughness of the springs. However, the most important use of steels of this type is probably in the manufacture of electrical machinery. It is possible to produce a silicon-alloy steel which has not only a greater magnetic permeability than the purest iron, but also, a high electrical resistance. Its hysteresis is, of course, low, this property always accompanying a high permeability. It therefore is a very valuable material for use in electro-magnets, and in electric generating machinery, is the most efficient material known.
In silicon-treated steels, the silicon is used somewhat as a scavenger, although it also produces results somewhat similar to manganese.