The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1873-01-04

boler--in fact 1t Is oitentimes employed for that
purpose. The steam within such boiler Is not SUI
perheated, and cannot SO lar as the practice Of
the world bears upon the point be called danger
Gus to the woodwork with which the boiler or
pipes may come into contact. But now we reach
q consideration which should be impressed upon
the minds OF all who wish to under stand
the dangerous conditions, at least so far a. the
communication OF fire to the adjacent woodwork
Is concerned. We have steam within our boiler
of more or less PRESSURE according to its tempera
ture, and lying upon water that is OF the same
temperature. This steam Is a gaseous body, and,
heat obeys law entirely different from that
under which it was formed-in word, 1t is practi-
cally like common air. TO get even the moderate
pressure Of fifteen pounds per square inch upon
boiler filled with air would require temperature
OF about four hundred and eighty degrees. This
temperature OF water would give US pressure of
steam OF about two hundred pounds. Here,
then, is the most important dilerence-that
high and dangerous temperature without re-
And now the question Is, under what circIm.
stances can this take place Not, it may be safely
said, by the application ofheat to the water which
formed the steam, but only when the steam Is
heated apart from the water or by the direct ac-
ton Of the fire upon the steam ITSELF We have
next to look Tor the circumstances under which
this separate heating OF the steam would be likely
to take place, to enable us to Judge when steam
heating apparatus would DC saie or dangerou s; ,o
kept in boiler to entirely cover the surfaces eX.
posed to the action OF the re II this be neglected
will take place to greater or lesser extent, de-
pending upon the quantity OF the surface thus
barred, the intensity OF the fire, and the rapdity
with which the steam Is drawn Off and used.
.Second-A boiler should be constructed SO as to
allow the water to remain upon the fire surface,
no matter how active the boiler may be. To secure
this the circulating spaces within the boiler should
be large enough to allow for the escape OF the
steam from the water without such ebullition as
would carry the water up with the steam, and thus
lay bare portion of the fire surface. In the pres.
ent search for active concentrated and economical
boilers so-called which generally means small
and cheap boiler for doing the work OF large and
expensive one, 1t is not too much to say that some
OF their forms In use are liable to this dispace-
ment OF the water, either from the small
| tubes OF which they are composed or
| from the circulating spaces around them.
| boiler can be made, and indeed has often been
| made, that would In this way superheat the steam
| to greater or lesser extent, even when supplied
| with the required quantity OF water, 1t may be
| that Fire Marshal McSpedon has sometimes found
boiler that was dangerous, either from lack Of
| the required amount Of water or from its ex-
| tremely vicious construction ana action. In the
| pursuit Of great econoSy In steam boilers,
| especially those USED for manufacturing purposes,
| It Is not uncommon to arrange for experimenting
| the steam, and extreme instances could be cited
OF the Ignition Of woodwork about such boilers and