Daily capital journal. (Salem, Oregon) 1903-1919, 1913-08-15
BATTLES SCIENCE.
Why Hot Steel Is Tempered by
a Sudden Cooling.
SLOW COOLING KEEPS IT SOFT

succeed IN Reasoning out why inns
10 so-The Mysterious Properties
Exhibited by Water, Tin and Glass.
Here is a fact, known to everybody,
which Is as mysterious as would be
the actual appearance of a ghost, by
which mean that the fundamental ex-
PLANTATION Of the phenomenon is about
as far beyond our reach In the one
case as In the other.
The fact to which refer Is the pro-
duction of tempered steel by quenching
in cold water. If hot steel is cooled
very slowly 1t becomes soft and cannot
take cutting edge, but If 1t is cooled
suddenly 1t becomes very hard and can
be ground into keen swords, knives
and cutting tools.
Now, why the dIfference1 Have you
ever thought about that question? If
you have not. many man Of science
has, and has been puzzled over 1t.
Here is another related mystery. If
you heat an old japanese sword. which
for centuries has retained its capacity
to slice of a head at a blow. or to
open swift passage for the soul Of
the victim Of the harakiri mania, to
the temperature Of boiling water 1t
gradually softens and loses the keen
ness that once made 1t so formidable.
1t is the same steel, but 1t, too, seems
to have lost its soul At tempera-
ture Of 100 degrees centigrade the
hardened steel commits harakiri In a
few minutes Surely there is some
thing strange In that
Then consider this: At zero tempera-
ture water changes from liquid and
suddenly becomes solid. But If you put
the water in vase and carefully pro-
tect it from dust you may cool it as
much as 20 degrees below zero and yet
1t will not freeze! But now shake the
vase or drop In a bit Of ice, and the
water Immediately solidi6es!
owe the collection of these facts to
a paper by Professor James Il. Wal
ton, Jr., Of Wisconsin university The
explanation which he gives is that SUBJ
stances like the hardened steel and the
unfreeZing water are in a state Of
suspended change" That accounts
for the phenomena. but in a certain
sense they remain mysterious, just as
life is mysterious
Many substances possess the same
curious characteristics. Professor Wal
ton says that If flask containing So
dium acetate, which has been cooled
below its natural freezing point with
out solidifying, is opened in room
containing dust Of the solid acetate the
fine particles of the latter dropping into
the flask will cause the whole contents
to solidify.
Tin Is very strange metal with re-
gard to this state Of suspended change
or "metastabllity." A severe winter cold
will sometimes cause 1t to lose its
hardness and crumble.
Objects made Of tin sometimes un.
dergo such change and are then said
to be suffering from "the tin disease"
The contact Of diseased" tin with
bright, hard tin is capable of setting
up the transformation.
Glass, Professor Walton informs us,
is ian undercooled substance"-that is,
II is in a metastable condition II old
glass tubes through which water has
frequently passed are heated the glass
crystalllzes and loses its transparency.
All substances in this state are liable
to change, and the change, under prop
er conditions, may be sudden. Hard
ened steel Is in a similar category. If
II were as perishable as tin 1t could not
be safely used for many purposes for
which It is habltually employed. For
tunately steel exhibits great resistance
to change Of state after 1t has been
tempered Transformation is retarded
or arrested.
Does steel slowly return to the sta
BILE form and thus grow softer2" asks
Professor Walton, and then answers:
That we do not know; we can only
say that II such a change does take
place hundreds Of years are necessary
to bring 1t about"
The same ancient Japanese swords,
which, when heated, as before describ-
cd, become soft, retain all their hard
ness II carefully preserved.
II is evidently Of the highest i'm
portance to the practical world that
science is investigating these things
and discovering the way and the cir
cumstances In which the changes come
about, even II It has not unveiled the
underlying mystery OF their cause
Garrett p Servlss in New York Jour
nal