Year: 1868

\ correspondent sends us a drawing and a
description of steam heating apparatus,
with a request for our opinion as to its
merits In an article published in the first
number of the current volume, we discussed
rhe subject of the supply of cold air to
furnaces employed Of warming buildings
The request of our correspondent has sug-
gested some general remarks upon the re-
lative merits Of steam and hot air for hea-
ting purposes, from which he may sufficient
" infer our views of the apparatus submit
ted.


There is a radical difference in the princi
pies Of fheating by steam and hot air which
cannot be overlooked in forming true
estimate of this subject The heat supph-
ed by steam apparatus is for the most part
radiated heat, and that supplied by hot air
| is conveyed by moving particles, and i'm
parted to the surfaces of bodies by contact.
Persons in a room heated by hot air solely
are, to use the words of Prof Silliman,
Immersed in hot air bath, and require
consequently, several degrees more heat by
the thermometer, for comfort, than when
radiant heat forms party of the means Of
an artificial temperature.


There is prevalent notion that air parts
with a portion of its oxygen in passing over
the heated plates of iron in furnaces. The
surfaces Of these plates, however absorb
very little oxygen, after they have become
in a measure protected by the coating of
oxide which always forms upon them. This
objection, therefore, only has force in regard
to new furnaces. The air is, however, vitiat-
ed by the products ofeombustion, not only
of the organic particles which are generally
imperfectly retained within their proper
channels.


A prevalent error in regard to the use OF
steam pipes, etc., from heating, may be
also noticed. It's thought by some that
to use a common phrase-"the heat Is not
so dry" as that obtained from furnaces.
The phrase, properly speaking is scientific
absurdity Heat is not thing like sponge
to soak up moisture But ifi is constructed
to mean that the air is more moist when
heated by hot air furnaces, an error is com
mitted, unless as in some cases special pro-
vision is made for keeping the air saturated
with moisture by small steam jets or their
equivalent,


The capacity Of air for moisture increases
with its temperature, and if the amount
necessary to completely saturate it, is not
artifcially supplied, it viii seize upon and
appropriate moisture from all objects with
which it comes in contact The skin and
the lungs are called upon to pay tribute, and
chapped hands and faces, bronchial and
increased sensibility of these organs must
Inevitably follow. A higher degree Of heat
is generally impaired to the air passing
through the fues Of furnaces than is effect
ed BY most kinds of steam apparatus From
this cause, and also from the fact that the
organic particles are not burned by them
the air is more wholesome in rooms heateC
by steam than in rooms heated by hot air


An entirely different plan for ventilation
! ought to be adopted when the fresh air ad
mitted to rooms is cold, than when it i
heated, as is the case with furnaces. Il
the latter case the pure air being heated
rises at once to the top Of an apartment, an'