Rutland weekly herald. [volume] (Rutland, Vt.) 1859-1877, 1873-09-11

sustains the liquid column in the cylin-
der is that of atmospheric pressure. |
| do not intend to convey the idea that
the weight ndlength of liquid column,
indicated by the use of piston, fixes the
limit OF the quantity that can be raised
when other means are used, for it is evil
dent that it the pressure should be re-
moved by an air pump, the air which
the liquid might contain at the COM
mencement of the experiment, as well
as the vapor arising from it, would be
removed. Consequently more perfect
vacuum would be formed over the LIQUID,
more pressure would be removed, and
greater amount of atmospheric pressure
called into play.
There is another cause which materi-
ally affects the cohesion of liquids,
which does not apply to metals, that is
pressure. 1t is fact well known, that
less heat is required to cause liquids to
boil on the top of high mountain than
at its base, and that more heat is re-
quired to cause liquid to boil in closed
vessel, as that of a steam boiler where
the water is subjected to the pressure of
steam, than would be required to boil
the same liquid in an open vessel
Therefore, in determining the cohes-
ion of liquids by means of hollow cyl
inder, or other mechanical means the |
conditions of temperature and elevation
must be taken into account And in
order to ensure uniformity of result and
accuracy. all experiments for determin-
| ing the cohesion of liquids should be
made on level with tide water, and at
| temperature of so degrees.
When Torricelli made his experiments
/ in 1913, which led to his great discovery
/ hat fI.n Of hO aff
| phere that sustained the water in his
! pipes He is said to have expressed his
views in relation to the other liquids as
follows *'.It now occurred to him,
that it really was the atmosphere which
supported this column of water in the
pipe, then, if he employed some other
liquid, the specific gravity of which,
compared with that of water, was
Inoaon, column of such liquid would
be sustained in the tube, Of a length pro
p0rt5o7eed to ats gravity" His expert
ments with mercury convinced him that
his conclusions were correct. With due
respect for the philosophers genius and
Judgment, | shall en0eavor to show
that his conclusion in regard to other
liquids was not a correct one, by sub
hitting the following, for considera-
ton:
Vacuums of the same degree of perfec-
ton cannot be formed over the surface
of water and volatile liquids, as can be
formed over mercury. Different liquids
boil at different temperatures, ranging
from 90 deg. the boiling point of ether,
up to 862 deg the boiling point Of
mercury. No vacuums can be formed
ever a liquid, whose temperature is at
the boiling point. The boiling points OF
liquids has no relation to their respfc
tive specific GRANTEES, as will appear
from the following
: Mercury boils at 662 deg. with spcci-
fic gravity of 10 $50.
, Sulphuric acid boils at $50 deg, with a
, specific gravity of 1.841.
Water hollis at 212 deg. with specific
gravity of l.
Alcohol boils at 173 deg, with speci-
, tic gravity of 1872 -...-
Sulphuric ether boils at 96 deg. With
specific gravity of .725.
1t is evident that if Torricelihad made
= his experiments with his apparatus, water
d and mercury, at a temperature of 2l2 deg.
no water would have assembled his pipe,
as its cohesion would have been destroy
> ed, while it would have required the adj
; dition $50 deg. to destroy the cohesion that
e still remained in his mercury
e The apparatus which | have used for
= measuring the cohesive strength Of liquids
: consists of a glass tube thirty-six inches
Z long, with one end closed, with an in
n side diameter of one inch, also smaller
Q glass tube of the same length, with an
a outside diameter of about one-half inch.
:, The diameters of these tubes should be
- such as to allow the smaller one to pass
Il freely into the larger one. On the out
n side of the small tube laid out thirty
If inch scale, commencing at q, three
inches from the top end, and number
ing downwards to 30 inches also scale
of three inches, laid out from o to the
top end of the tube On some of the
small tubes these scales were made on the
n glass itself, and on others they were
IT made on a narrow strip of white paper,
2 pasted on the glass. On the upper ends
of these tubes brass plates or caps were
tightly fixed, through which small Ia
pering hole was made, that could be
closed with a brass plug ground to a
e fit.
~ After the large tube has been support.
e ed in vertical position, sufficient
= quantity of mercury is put into it, tc
IN allow the small tube to be immersed tC
~ o. the starting point of the two scales
. The air ia the small tube being permitted
30 TO pass out through the tapering hole II
= the cap, allowing the mercury to stanc
= at the same levelin both tubes, leaving
as the three-inch scale above the mercury
al The upper part of the small tube IS the1
no filled Through the hole in the cap plate
~ with the liquid to be tested. The hole
IL in the cap-plate is then closed with thu
- plug. By raisiOg the small tube out o.
y the mercury, it will remain filled unit
or the weight of the mercury column, thu
A. raised, equals the cohesion of the liquid
10 at which point it will be seen to break
~ The length of the mercury column sus
~ tanned by the operation can be readily
he noted on the thirty-inch scale. To th
~ weight of the mercury sustained IN tn
81 tube add the weight of three inches o
~ the LIQUID that is in the test tube, thi
will give the cohesive strength, pc
III | square inch, of the liquid, at the temper
Nv, ny allure it had when the test was made.
~ During the progress of an experiment
oc lust before the rupture of the liquid o6
reI ours, an innumerable number OF mlnut
: air bubbles can be seen scattered thrQug
on the entire body of the liquid. The re
: ! moval of the atmospheric pressure a
nc lows the air contained in the fluid to ea
Loo pand sufficiently to cause a perceptibl
= frightening of the column. As soon q
the rupture occurs, the space produce
nor by the separation is Immediately file
1,id with vapor, and at the same time th
the ar oo.poleo ~ ~ nv
ed After pressing the small tube dow
tba into the mercury nearly to 0, the plu
;nG is removed, when, by further pressin
80 ~, the tube into the mercury, sufficient
Ios- to cause the liquid to just fill the hole I
'o' the cap, the vapor and air arising frol
&c the first operation will be removed. B
- ~ replacing the plug, and again raising tt
w. ~ tube, less amount of air and vapor wi
be seen to enter the vacuum space, and
81 % longer column of mercury will be su
90 tanned in the tube.
,na These effects were observable for thr