Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1912-10-30

bic OF bearing fifty atmospheres Of ten
sion. or $50 pounds to the square inch
II It was possible. then. to utilize this
property by making a rope" OF water
we should find it capable OF sustaining
a good fraction Of the weight that
could be borne by an ordinary rope OF
the same size. But IL must be admit
ted that the task of making a rope out
Of such material would be rather diff
fcult. 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 II would have to be inclosed in a
tube: but. while II would here be in
condition to Withstand compression, as
from a 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. Ii
was then slowly and carefully cooled
back to its original temperature. when
II was found that the water had not
contracted. but still filed the tube.
1t is almost a universal law that
small extension in volume of a body
requires the same magnitude OF force
to produce II as TO cause q 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
water that now fills the tube must be,
under tension. since previously at the
same temperature II did not quite ill
the tube-that is. IL has actually been
stretched or expanded beyond its nor
NAL volume for this temperature, and
| from our knowledge of the forces that
would be required to produce the cor
responding compression we can figure
| out what this tension must be.
The ultimate particles or molecules
| OF matter we believe TO be held to-
gether by powerful forces, known va
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. II might be thought that these
/ forces would cause two bodies in con-
tact to adhere TO each other. but par
ticles have to be so near together to
be acted upon by them that it Is diff
ficult 10 bring bodies into such close
contact that an appreciate area Of
one is within this distance OF the other
However two clean pieces Of lead
can readily be pressed so closely to-
gether that they will adhere. and a
set OF copper cubes was once made
with such true faces that when a doz-
en- Of them were piled one on top Of
the other the series adhered together
so well that the whole could be lifted
from the top one But the best ex-
ample is furnished by pieces Of op-
teal glass whose surfaces have been
worked so plane that when pressed to-
gether they Will as readily break at
some other spot as at this plane
Perhaps II is unfortunate that these
useful forces. which hold all matter
together and keep II from collapsing
into impalpable dust. are confined In
their action 70 such limited range.
II this were not so. a break OF any
sort could be fixed 10y merely bring.
ing together the broken ends. Glue
Of any kind would be unnecessary.
But even this state OF affairs would
have its drawbacks. A book laid on
a table would have to be pried of with
wedge. and the same instrument
would be required TO open it Ev-
erything would stick to everything
else. and the pleasure Of walking
would be lost in the tedious process OF
pryinE first one foot and then the 9th.
er from the viselike grip OF the side
walk or the tOor.-Boston Post