Worcester daily spy. [volume] (Worcester [Mass.]) 1850-1888, 1860-07-18

the subject of the recent disaster TO the memo
sha, and other boiler explosions not caused by
the low state of water in the boiler, mentions
a theory advanced by Mr.. NORMAN WIZARD,
a practical scientific mechanic, whose prom
cheney in poly technics has already given HIM
an enyiable distinction Mr.. WIZARD has adj
vanced the proposition that explosions are
caused By the action Of superheated steam upon
the ,cater. BY the term "superheated' it is not
understood simply "dry steam," but vapor
whose absorption,o or assimilation of caloric, has
been such as to intensity its power, while it
raised it temperature above that of the water.
The Sentinel says:
Although our knowledge of the chemical re
lation which these two elements in this state
sustain, is limited, the fact that steam can be
heated to an intensity sufficient to make iron
red hot is not questioned. If therefore the
body of steam in boiler absorbs heat from
any conducting substance, such as the stay
rods, or bars, which pass up from the furnace
plate of vertical boiler, it is plain to see that
the two elements assuming relative condition
which has not yet been considered by writers
on this subject If the temperature of the
steam is 342 deg, the pressure will be 100
pounds. If it rises to $50 deg the pressure
will be 1000 pounds to the square inch. The
disproportionate ratio will give an idea of the
suddenneSS of any effects which must follow
from such an accumulation.
Mr.. Wizard assumes that the steam in
boiler has acquired this temperature over that
of the water. There then remains but the in
terpostion of some such force as the opening
of the throttle valve, to induce break in the
surface of the water; and Immediately the
fluid is eXpounded, taken up like gunpowder,
and an explosion is Il e consequence. 10 rem.
der this easy OF comprehension to the unscien-
tific reader, it will be necessary to state that
the water only be heated by currents.
| Heat is not transmitted through it, other than
| by mechanical action of the particles, which
| are displaced as they become lighter, and
others taking their place produce current
| AS there will be no sensible effect upon the
water then, remaining under pressure, and
receiving the heat from above, it will also be
seen that the moment current of steam is in
duced, by the starting of the machinery, that
a chemical change will be affected in the
water. If it is converted into steam as instan-
taneously as Mr.. Wards theory asserts an
explosion is the natural sequence. To reduce
this all to an axiom, we may say--the steam
must not rise in temperature much above the
water.
Mr. Wizard has devoted great deal of time
to the study of this important branch of
science, and the result of his labors has been
the invention of a double thermometer which
will indicate the temperature both of the steam
and water, and thus tell the approach of dan
ger Immediately. In throwing this article to.
gether, we are not sure that we have expressed
Mr.. WARDS ideas clearly but we think the
theory, whether controvertible or not, points
IN the right direction and in the hands of COM
petent men, may at least throw some new light
upon one OF the most Important questions of
the day
An important discovery in relation to explo-
sions caused by pumping cold water into heat
ed boilers, is said to have been made by Mr.,
Geo. E. Parry, of Philadelphia. The Evening
Bulletin of that city thus speaks of it.:
BY series of experiments he had satisfied
himself that the primary cause of boiler ex.
plosiOns was electricity, which under certain
circumstances would accumulate in the upper
part of boiler, and explode, unless it could
be carried off. He therefore contrived an in
sulated metallic rod, introduced into the upper
surface of the boiler, which would have the
effect Of carrying off the dangerous fluid At
taching this to Il large sized boiler, he tried the
experiment OF evaporating, under a heavy
pressure, nearly all the water from it, contin-
uing the fire until many portions of the boiler
became red hot, the pressure being still kept
up. Into this red hot and nearly empty boiler
nearly thirty gallons of cold water were pump
ed. This, according to all steam experience,
should have caused an instant explosion but
none occurred, and it was naturally inferred
that the insulated metallic rod had carried off
the electricity and prevented the explosion.
The boiler that furnishes steam to the engine
OF the Bulletin office being within a few feet
Of the desks where editors and reporters do
their work, we thought it at least prudent to
avail ourselves OF this invention and we had
one of the insulated metallic rods introduced.
Some mouths ago leak occurred in the boiler
above the fire line, and as it was enclosed with
in brick walls it was not discovered until the
water got very low. In short time parts of
the boiler become over-heated and when rub.
bed with an iron poker, emitted sparks 1t
was just the hour for going to press, and the
position was embarrassing, if not alarming.
TO pump cold water into a boiler in that con-
Oition is generally regarded as dangerous. But
our engineer, Mr.. Frederick Freas, having
faith in the electric rod, started the pump and
filled the boiler without accident. The leak in
the boiler was caused by expansion and con.
traction; it suffered no further damage from
the severe test it underwent. Within about a
week after this occurrence in our office the
boiler of a steamboat in Easton, unfinished
with the electric rod, exploded, killing fifteen
or twenty persons. The explosion was caused
by the injection of cold water into an over
heated boiler-a thing that we had done with
impunity only short time before.