The Grenada gazette., 1888-01-28

sero me 1esQo Whteh Drlves tn
hns'ess eetAs Oesatsy.
! y will begin nov. and ask you what
q steam engine isr' .5ss
whats asteam engine? Why, lis
TINS machine here. that drives the mill
That's easy enough"
why does steam let into amachine
drive ite Common air let into Il
wouldn't drive il. would ite" s..
,"No, SIR"
'Then there must Dc something
about steam different from othe /
huids. such - air (for air is a fluid the
same as water), 10 fit it for motive
power?' 65.r+ ~. n,
''Yes, SIR" fs
''Well let us see II we can find out
what peculiarities it has Air and
steam are Just the same in one respoc.
they are both Auids--or flow like
duids, and are therefore called fluid
gasses and either one. under pressure,
would move an engine; both are
capable Of expansion and contraction
In nearly equal degree. 80 nearly that
the laws of one govern the other.
and'-
"Hold on. now, my friend; you are
getting too fast. You are Just like all
the fellows who under take to tell .
man who has had no chances some.
thing about his business. Get back.
will YOU to where you started. and
tell me why steam drives an engine. !"
by reason Of its elastic iorcc7"
"And how does 1t get that force?"
"From being coiled up-just as Z
spring is wound up-by heat. Steam
is the vapor Of water, and arises from
it at all temperatures above zero. You
can see it any cold morning cvaporat.
ing into tho air from the surface of =
pond" ,..,...l...
7 well that's all right. have seen
it, though didn't know it was steam.
but since the yapor Of water is steam.
I Suppose it was. Now would that
steam drive an cngine?'
mo. not at tho pressure at which il
is generated. When you see the vapor
Of water rising from pond it is nj
the same pressure as the atmosphere,
and has no force above atmospheric
pressure; but the same vapor con.
tinued in a boiler. and compressed by
the constant addition Of more vapor
generated by heat. will increase to any
required pressure"
Then all there is about steam ia
that it Is the vapor of water, and
gets its elasticity from being confined
in a close vessel like 4 steam boiler
10 that itp'' , r.
THAT is the exact fact. Steam ut
the pressure Of the atmosphere is pre-.
'cisely the same as steam ut $50
pounds per square inch; only differing
in the intensity Of the force. If you
let steam Of $50 pounds down to at.
mospheric pressue again, you see It
is the same old thing. and if corr
densed. 1t finally becomes the water
1t was generated from. p"
"Ain't steam some kind Of a gas
that will explode If touched of at high
pressurc?'' ....r.- .s.
mo; the water Of winch the steam
is madc consists of two gases, oxygen
and hydrogen, and the steam itself is
Just the same. Now these gases can
be divided as you would say, or sepa.
rated again BY destroying the steam;
that is by forcing it through tube
heated white hot. The oxygen likes
the hot iron better than it does the
hydrogen. and goes for it while the
hydrogen-glad to get rid Of the
oxygen-goes on by itself. Now. il
these two gases. oxygen aud hydrogen.
are brought together in stout re.
cciver. IN certain proportions. they can
be ignited and exploded by an
electric spark. and their union results
IN water, but to explode either of the
gases alone requires certain amour,
Of common air to be mixed with ,henl.
and this is not found in q steam boiler
That's what You mean. suppose, by
steam turning into gas. is it notP"
'.Well. yes; read somewhere that q
boiler blew up once because the steam
was red hot, and turned into gas, and
l was kinder interested In that part of
your story. for l sometimes get this
old kettle pretty hot myself. and ]
wanted to know il there was any
truth in it."
"There isn't the slightcs'. Under
the conditions under which steam is
used in steam boiler, it might get
even rod hot, and there would be no
danger whatever unless there was
sufficient surface Of red hot iron to
absorb the oxygen, and atmospheric
mir admitted in sufficient bulk 10 dilute
the hydrogen to the explosive point.
That's cross roads notion Of the
cuuse of steam boiler explosions
which you must pay no attention to
whatever All you've got TO do is to
keen scant three gauges OF water in
that boiler; keep tho safety valve In
oood order. and 20 ahead. Milling