* * * * *




TEMPERING BY COMPRESSION.


L. Clemandot has devised a new method of treating metals, especially
steel, which consists in heating to a cherry red, compressing strongly
and keeping up the pressure until the metal is completely cooled. The
results are so much like those of tempering that he calls his process
tempering by compression. The compressed metal becomes exceedingly hard,
acquiring a molecular contraction and a fineness of grain such that
polishing gives it the appearance of polished nickel. Compressed steel,
like tempered steel, acquires the coercitive force which enables it to
absorb magnetism. This property should be studied in connection with
its durability; experiments have already shown that there is no loss of
magnetism at the expiration of three months. This compression has no
analogue but tempering. Hammering and hardening modify the molecular
state of metals, especially when they are practiced upon metal that is
nearly cold, but the effect of hydraulic pressure is much greater.
The phenomena which are produced in both methods of tempering may be
interpreted in different ways, but it seems likely that there is a
molecular approximation, an amorphism from which results the homogeneity
that is due to the absence of crystallization. Being an operation which
can be measured, it may be graduated and kept within limits which are
prescribed in advance; directions may be given to temper at a
specified pressure, as readily as to work under a given pressure of