Loudon free press. (Loudon, Tenn.) 1852-1855, 1853-03-19

Wv
oAs ESGINEs-In our last article on this sub
+ Jec1 we pointed out the reasons why the gas en-
{ gl;les which had been invented to suppressed
] steam had all failed to compete with it. W,
van now proceed to give the reasons why Ho
an has hitherto failed and must continue to fai
4 IN competing with steam as a force to move ma
, chinery.
ali oodles In nature exist in either of three
conditions, viz solids, liquids, and gasses. DIFF
ierent laws govern these three different con
ditlonS of matter, and many bodies can be easi
y yconverted into any of these three conditions
A certain amount Of heat applied to ice will
change it into liquid, and the application of a
sreater amount of heat viii change it into va
s,s,-steam. All bodies suffer a temporary in.
cEase OF dimensions when heated, and contract
9saln into their original volume on COOLING
It is this feature of the expansion of bodies by
beat, which enables man to employ them to
move machinery. Thus by heating bars of iron
the walls of building in Paris were brought
straight-thrust from an incline to perpendic-
ular;-thus by heating air in balloon, Mont
golfer was enabled to force his way upwards
against the pressure of the atmosphere, and bv
cheating water till it became steam, Hero was
enabled to whirl round his primitive rotary en-
/ gine. Now the question which we are TO dis.
! cuss, is what body in nature is the most econom-
lcal as motive force, whether solid. LIQUID.
or gas There is no use iii losing time speak
ing OF the solid, therefore we will speak only of
liquids and gases, and only of one liquid, and
one gas--water and air.
The principle of any chemical force to propel
machinery depends on the nature of the sub
stance employed; thus water by heat being ap
Piled to it. expands to l,728 times its bulk; it
is this elastic force-water combined with heat
which moves the piston in the cylinder of an
engine Air by having heat applied to it also
expands, and this expansive force admitted un-
der the piston of an engine, will also move it.
Now, if water and air expanded equally with
the same amount Of heat applied, and were 9TH
erwise alike easily condensed to their original
bulk no one could doubt the propriety and econ |
omy of using air in place of steam as a motive |
power, but this is not the case. Steam and air
alike, come under the law of Mariotte in expan- |
ding their bulk equally with the same amount |
of heat applied, namely, doubling their volume
for every 1912 of heat applied, A cubic foot of
air at 320 cannot move the piston of cylinder, |
hpt hYt it, if 49l99 4s9l9clhl beat e;fAtra aFRf Ffta
a a pressure OF IS lbs. on every square inch of
piston of IA inches area. But cubic foot Of
water at 2l2o sensible heat converted into steam
at the same pressure will lift 3, 732, ,48O lbs one
foot high. Air is not for moment then to be
compared to water, bulk for bulk, to exert elas-
tic force by the application of heat; this is evi-
dent, for the latent and specific heat of steam
is only l,l840 Allowing it to be safe to en-
plov heated air (but it would not) about 48l0
to double its original volume, it viii require 864
cubic inches of air, at 800, to which 49l0 have
been applied, to equal one cubic inch of water
sr.;sed into steam from 320 Thus there is q
- ference between liquid and gas to
.........4eat have been applied, in the expansion
of their bulks-their elastic force. To make
air triple its volume it would require to be heat
ed 70 782o-a low red heat. In its very nature,
Steam seems to have been designed by
Wise Providence, as a mighty power suited for
the propelng of machinery, for while it con-
tans ilSl0 of heat Qatent and specific combin-
cd( vet it has only 2120 of sensible heat, and in
this respect combines heat land consequently
a force) of an intensity and in such form as
dare not be applied to air.
The boilers of the steamship Atlantic evapo-
rate II lbs. of water by one of coal, that 2O8'36
cubic inches of water, which by such small
amount of coal is converted into 36S,31SO9 Gu
bic inches of steam. VIII one pound of coal
thus expand 2O7 cubic inches of air to LIS
times its original bulk at 800? Unless it does it
is more expensive than team,and besides steam
can be condensed at an expense of only three
ffteenths Of the power Of atmospheric resist
! auee. and air cannot be condensed at all to Its
ORIGINAL volume, until the whole Of its heat is
abstracted. Thus from its nature water has
many advantages over heated air-the fluid over
the gas. No wonder all the Hot air Engines
hitherto invented have failed to compete with 1T
We have not said anything yet about the ex
haustion of expanded gases from engines, the
principal and cause by which they are enabled
to act; we will do so next week. 1t would ex
tend this article to an undue length, to ado
what we have to say now, every article, howev
er. is complete in itself.-Scie,ttic american.
d
yDIssoIyING THE UNIoY.-Reese &. Price, {
resident of Cincinnati, who is possessed of con
siderable of this worlds goods, has made pro
, position to the Legislature of Ohio, for disc
: luton of his partnership with the State. HI
r consideres the notions of Commonwealth an
: tagonistic to those entertained by himself, ant
? does not desire fellowship with it. He propose
: to pay his portion of the State debt, which h
i estimates at $500, and be absolved from all al
r legiance.
i At the ceremony admitting ex-Bishop Ives t
the Catholic church, at Rome, DR.. Ives handle
: to the Pope the Episcopal cross, ring and sea
9 saying, 'Heavenly Father, these are the sign
e ofmy rebellion to which the Pope replied
e 1It is our will these signs of your submission