Inventors at Work, with Chapters on DiscoveryIles, George
History
Inventors at Work, with Chapters on Discovery
Iles, George
Inventions -- History; Inventors
We have so long been accustomed to thinking that there must be iron in
everything magnetic that we hear with astonishment that metals each
insusceptible of magnetism, when united strongly display this property.
Such is the discovery of Mr. Fr. Heusler, of Dillenburg, near
Wiesbaden. He noticed one day that an alloy of manganese, tin, and
copper adhered to a tool which he had accidentally magnetized. In the
course of experiments Mr. Heusler found that carbon, silicon, and
phosphorus did not confer magnetism; while arsenic, antimony, and
bismuth did so, all three metals being diamagnetic, that is, placing
themselves at right angles to a common steel magnet above which they are
freely suspended. An alloy of remarkable magnetic strength was composed
of copper 61.5 per cent., manganese 23.5 per cent., and aluminium 15 per
cent. This alloy is brittle and considerable changes of temperature but
slightly affect its magnetism. When a little lead is added magnetism
disappears between 60° and 70° C. This alloy therefore is magnetic when
placed in cold water; when the water is heated the magnetism disappears
before the water boils, only to reappear when the water cools. The main
interest of these discoveries is that the new alloys bridge the gap
betwixt magnetic and diamagnetic bodies, that is, they join the iron,
nickel, and cobalt group, which place themselves along the line of a
magnetic field, with the diamagnetic elements, bismuth, antimony, zinc,
tin, lead, silver, and arsenic, which place themselves at right angles
to the lines of a magnetic field. We have been accustomed to suppose
that magnetism is a property possessed by only a few elements; these
alloys show us that magnetism may arise as a result of grouping atoms,
none of which by itself has any magnetism whatever. Indeed it may be
possible to make an alloy more magnetic than iron, furnishing the
electrician with electro-magnets of new power.
Anti-Friction Alloys.
We have briefly glanced at recent progress in the art of alloying in so
far as it has produced steels of new strength, elasticity, or hardness;
new ability to resist abrasion or high temperatures, new capacity for
magnetism, new indifference to changes of temperature as affecting
dimensions. Alloying has of late years conferred other gifts upon
industry, of which one example may be cited from among many of equal
importance. Friction levies so grievous a tax upon the mechanic and the
engineer that they are quick to seize upon any material for bearings
which reduces friction. As the result of extensive experiments Dr. C. B.
Dudley recommends an alloy of tin, copper, a little phosphorus, with ten
to fifteen per cent. of lead. He finds the loss of metal by wear under
uniform conditions diminishes as the lead is increased and the tin
diminished.
Influence of Minute Admixtures.
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