Heppner gazette. [volume] (Heppner, Morrow County, Or.) 1892-1912, 1911-09-07
A ROPE OF WATER.
Berthelot'S Test That Showed Its
Tensile Strength.
THE COHESION OF MATTER.

1t is well known that liquids art
among the least compressible of sub
stances; this in spite of the fact tha
they have the property of conforming
to any shape Of vessel or Of yielding
to any forces, no matter how small
which tend TO change only their shape
Thus, to squeeze water into nine
tenths of its volume under ordinary
conditions would require a pressure
of no less than 1900 atmospheres, OF
$4,000 pounds, to the square inch
This property of being almost iReom-
pressible is best illustrated perhaps
by an experiment tried centuries ago,
wherein an attempt was made to COM
press water by filing a leaden shell
with it and then. after closing, ham
mering and squeezing the she'll The
only effect of the tremendous. pres
surcs produced in this way was to
cause the water to penetrate the mi
mute pores of the lead and exude in
drops like per&piration ON the outer
surface of the shell. The same effect
was found for a silver shell.
But, while it is a familiar fact that
liquids Will resist an enormous force of
compression, the companion fact that
they are also capable of withstanding
tension is not so generally known. At
first sight this statement may appear
ridiculous. When water may be so
readily dipped from pail or poured
from one vessel to another how can
it be capable of withstanding tension?
If. however. we prevent change of
form we find that pure water is capa-
Bile of bearing fifty atmospheres of ten
sion, or 750 pounds to the square inch.
If it was possible, then. to utilize this
property by making a rope" of water
we should find 1t capable Of sustaining
a good fraction of the weight that |
could be borne by an ordinary rope of |
the same size. But 1t must be admit
ted that the task of making a rope out
of such material would be rather diff
ficult, to say the least Notwithstanding
the fact that it possesses this desirable
property Of tensile strength. Because
of its inability to resist a deforming
force it would have to be inclosed in a
tube; but, while 1t would here be in
condition to withstand compression, as
from piston In the tube, any attempt
at stretching" the liquid in this way
would simply result in pulling away
the piston from the water surface.
However, this tensile strength was
actually found by Berthelot in the fol
lowing way: A strong glass tube sealed
at one end and drawn out very fine at
the other was filed nearly full of wa
ter and then closed. The tube was then
cautiously heated until the water had
expanded and completely filed it. 1t .
was then slowly and carefully cooled .
back to its original temperature, when
1t was found that the water had not
contracted, but still filed the tube. !
1t is almost a universal law that q !
small extension In volume of a body ,
requires the same magnitude of force
to produce it as to cause a similar
amount of compression, the forces, how.
ever, being tension in one case and !,
compression in the other. With this :
law in mind it is readily seen that the n
water that now fills the tube must be n
under tension. since previously at the a
same temperature 1t did not quite fill II
the tube-that is, It has actually been I,
stretched or expanded beyond its nor n
NAL volume for this temperature, and o.
from our knowledge Of the forces that e,
would be required to produce the cor lie
compression we can figure al
out what this tension must be. 81
The ultimate particles or molecules Il
Of matter we believe to be held to- b,
gether by powerful forces, known va pr
riously as cohesion or adhesion. but -
being in any case forces of attraction,
and these forces tend to prevent any
expansion Of the matter, be it solid or
liquid. 1t might be thought that these n
'orces would cause two bodies in con- |
act TO adhere to each other, but par
iclas bovo - -, 90 - .oo.ott'o - ap
'e acted upon by them that it is diff 0'
icult TO bring bodies into such close ex
ontact that an appreciable area of ce
ne is within this distance of the other. ag
However. two clean pieces of lead to-
an readily be pressed so closely to- in,
ether that they Will adhere, and q a.
ct Of copper cubes was once made
Tith such true faces that when a doz- - =;
n of them were piled one on top of nm
he other the series adhered together Ar
o well that the whole could be lifted
rom the top one But the best ex-
mple is furnished by pieces Of op-
cal glass whose surfaces have been
-Orked so plane that when pressed to-
ether they viii as readily break at
Dme other spot as at this plane.
Perhaps it is unfortunate that these
seful forces. which hold all matter
'gether and keep It from collapsing
ito impalpable dust. are confined in
leir action TO such a limited range.
this were not so. a break OF any
'rt could be fixed by merely bring
e together the broken ends Glue
any kind would be unnecessary.
But even this state Of affairs would
i've its drawbacks A book laid on
table would have 10 be pried Of with
wedge, and the same instrument
ould be required % open it. Ev-
ything would stick to everything
Se. and the pleasure Of walking
Ould be lost In the tedious process Of
ying first one foot and then the 9TH