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The Wisconsin lumberman, devoted to the lumbering interests of the northwest
Volume III. Number 6 (March, 1875)

Bearings,   pp. 501-502 PDF (780.1 KB)

Philosophy of the welding of metals,   pp. 502-503 PDF (764.4 KB)

Page 502

5he Wsicousin Lswnbenna.
bearing may then be considered as a series
of layers of soft metal enclosed in a casing
of metal almost as hard as the arbor it-
self. The microscope reveals this disposi-
tion very evident; and if one of these
bearings be carefully submitted to heat, so
as to cause the soft metal to run, the rest
remains in the form of a spongy mass.
The results obtained with various kinds
of bearings used on the Belgian and Ger-
man railways are thus givan: Bronze com-
posed of 83 parts of copper and 17 of tin,
costs 3 fr. 25 c per kilogramme, and wears
at the rate, of 11-6 grammes for four bear-
itns per 1,000 kilometres, the cost being
07 fr.; bronze containing 32 parts of
copper and 18 of tin costs 01032 fr.; the
same applied to carriages with brakes,
wears at the rate of 109 5 grammes, and
costs 0 335 fr.; white metal, composed of
3 parts of copper, 90 of tin, and 7 of
antimony, costs 3 fr. 73 c., wears at the
rate of 14 8 grammes, and costs 0 055 fr.;
'ditto containing copper 5, tin 85, and
antimony 10 parts, costs 3 fr. 66 c., wears
at the rate of 11 3 granimes, and costs
041 fr.; ditto composed of lead 84, and
antimony 16 parts costs 1 fr. 84 c., wears
at the rate of 12-2 gra mes, and the
expense is 0-018 fr. per 1,000 kilometres;
lastly, phosphorus bronze costs 4 fr. 37 c.,
wears at the rate of 2-3 grammes, and the
expense Is 0.010 fr. only, but when applied
to carriages with brakes, the wear rises to
9.5 grammes, and the expense to 0 041 fr.
Philosophy of the Welding of Metals.
The science of molecular mechanics is
is yet in its infancy, and for this very rea-
son it presents a rich field for investiga-
tion and experiment. We are already ac-
quainted swith iron, for example, in very
many   physical conditions.  We have
learned within a few years how to obtain
itmelted like steel and cast iron. But
how numerous are the things which yet
remain for us to learn, in order to under-
stand the properties of even these various
states of iron, in order to explain the pecu-
liarities which they present when viewed
from the standpoint of construction; in or-
der to establish the relation which should
subsist between these molecular states and
resistance of the metal under various
strains, in order to have as difinite a theo-
ry for working iron cold as for working it
hot. This knowlelge which may be caled
the physics and molecular mechanics of
iron, is still very rudimentary.
I will attempt to lay before you a sketch
of what I foresee in these molecular atud-
ies, at present unfortunately too much neg-
lected. I will enter upon the subject
through a phenomenon well known to eve-
ry one.
It is a matter of common knowledge that
iron is capable of being welded; that if
two pieces of iron be heated t) a tempera-
ture called for this very reason a welding
heat, and then be pressed together, either-
by hammering or by energetic presure,
the two pieces will be firmly united, i. e.,
welding tegether. Why is this? The
only explanation which we can 1ind in the-
best works on chemistry or metallurgy is
the following:-"At a white heat iron ac-
quires the property of being welded, a
property which it shares with the metal
platium only." But obviously there is no-
evidence here of any mysterious and spec-
ial property called "weldability," there is
only the effect of a very general cause,
the manifestation of a molecular property
elsewhere abundantly active in nature.
Take two pieces o~f ice, and at a t3m-
perature a little below zero, press them
very gently together, they become at once
welded to each other. This is the phenom-
enon, first observed by Faraday and subse-
quently investigated in so fascinating a way
by Thompson and Tyndall, which has re-
ceived the name of "regelation." Thomp-
son explains it in the folloming manner:
For all bodies, like water, which have the
property of diminishing in volume as they
liquefy, pressure, whi.h tends to bring the
molecules closer  together, lowers the
temperature  of fusion.  Consequently,.
when two pieces of ice are rubbed against
each other, fusion takes pla.e between the
surface of contact, at a temperature below
zero. Of course, as toon as the pressure
ceases, solidification is again produced, and.
the pieces are welded together.
It seems to me that the welding of iron
is a phenomenon exactly similar to regela--
tion. Such cases of actual regelation or
welding of iron are sometimes seen in the
welding of a spindle to its step when heat-
ed by friction, in the absence of any lubri-
cating fluid. The two pieces of iron are
brought to a white heat, that is to say,.
more or    less  near   to the  fusion
point.  The   repeated  blows of   the
hammer, or the pressure of rolls, lowers
the point of fusion and causes a superficia'
liquefication of the parts in contact, and
thus welds the masses together; and this
because like water, iron dilates in passing
from the liquid to the solid state. Many
other metals are similarly endowned, they
all, therefore, may be welded like iron, if-

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