were, a living fire. Were we not, how could we be always warmer
than the air outside us? There is a process; going on perpetually
in each of us, similar to that by which coals are burnt in the
fire, oil in a lamp, wax in a candle, and the earth itself in a
volcano. To keep each of those fires alight, oxygen is needed;
and the products of combustion, as they are called, are more or
less the same in each case--carbonic acid and steam.

These facts justify the expression I just made use of--which may
have seemed to some of you fantastical--that the fire and the
candles in the crowded room were breathing the same breath as you
were. It is but too true. An average fire in the grate requires,
to keep it burning, as much oxygen as several human beings do;
each candle or lamp must have its share of oxygen likewise, and
that a very considerable one, and an average gas-burner--pray
attend to this, you who live in rooms lighted with gas--consumes
as much oxygen as several candles. All alike are making carbonic
acid. The carbonic acid of the fire happily escapes up the
chimney in the smoke: but the carbonic acid from the human beings
and the candles remains to poison the room, unless it be
ventilated.

Now, I think you may understand one of the simplest, and yet most
terrible, cases of want of ventilation--death by the fumes of
charcoal. A human being shut up in a room, of which every crack
is closed, with a pan of burning charcoal, falls asleep, never to
wake again. His inward fire is competing with the fire of
charcoal for the oxygen of the room; both are making carbonic acid
out of it: but the charcoal, being the stronger of the two, gets
all the oxygen to itself, and leaves the human being nothing to