Little Falls herald. [volume] (Little Falls, Morrison County, Minn.) 1889-1950, 1913-09-19
BATTLES B 4 ! / SCIENCE e !
Why Hot Steel IS Tempered BY.
a Sudden Cooling.
SLOW COOLING KEEPS IT SOFT

SLOW COOLING KEEPS IT SOFT
Yet the Busy Brain Of Man Cannot
Succeed In Reasoning Out Why The
10 so-The Mysterious Properties
Exhibited by Water, Tin and Glass. 4
Here is fact. known to every body.
which Is as mysterious as would be
the actual appearance Of 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 it becomes soft and cannot
take cutting edge, but If it is cooled
suddenly it becomes very hard and can
be ground into keen swords knives
and cutting tools. :Sf.
Now: why the difference? Have you
ever thought about that question? 1t
you have not. many man Of science
has. and has been puzzled over It.
Here is another related mystery. II
you heat an old Japanese sword, which
for centuries has retained. its capacity
to slice OF head at 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 It, too. seems
to have lost its soul. At tempera-
ture Of $50 degrees centigrade the
hardened steel commits harakfri IN
few minutes. Surely there is somer
thing strange in that. .s~..
Then consider this: At zero tempera-
ture water changes from liquid and
suddenly becomes solid. But II you put
the water in vase and carefully pro-
tect it from dust you may cool it ~
much as 20 degrees below zero and yet.
it will not freeze: But now shake the
vase or drop in hit Of ice. and the
water Immediately solidi6es!
l owe the collection of these facts to
paper by Professor James H. Wat
ton. Jr.. Of Wisconsin university. The
explanation which he gives is that sub
stances like the hardened steel and the
unfreezing water are in state Of
suspended change That accounts
for the phenomena. but In a certain
sense they remain mysterious, just as
life Is mysterious. .s> .:..a
Many substances possess the same
curious characteristics. Professor Wat !
ton says that, If a flask containing So
dunn acetate. which has been cooled
below its nataraA 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 wifi cause the whole contents
to solidify. -.
Tin is u very strange metal with re-
gard to this state Of suspended change
or :.metastabilfty." A severe winter cold
will sometimes cause it to lose ttA
hardness and crumbie.
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 il capable Of setting
up the Transformation. g@.E. @.a
Glass. Professor Walton informs us.
is IAN undercooled substance"-that Ia,
it is in a metastable condition II old
glass, tubes through which water has
frequently passed are heated the glass
crystallizes and leses it's 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 q similar category. IL
It were as perishable as tin it could not
be safely used for many purposes for
which it is habitually employed. For
tunately steel exhibits great resistance
to change Of state after it has been
tempered. Transformation is retarded
or arrested
docs steel Slowly return to the sta
BILE form and thus grow softer?" asks
Professor Walton. and then answers:
THAT we do not know: we can only
say that If such a change does take
place. hundreds Of years are necessary
to bring it about"
The same ancient Japanese swords.
which. when heated, as before describ-
ed, become soft, retain all their hard 4
ness If carefully preserved. #
It 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 If It has not unveiled the +
underlying mystery Of their cause
Garrett p. Serviss in New York Jour !.
nal 81.
Correct Interpretation Essential. S H
Many Of the most beautiful pieces /
Of poetry In literature would seem I'M 3