the carbon (not carbon in a free state, but, as in this case, placed ready
for action at the moment), and makes carbonic acid, and is so thrown out
into the atmosphere, and thus this singular result takes place: we may
thus look upon the food as fuel. Let me take that piece of sugar, which
will serve my purpose. It is a compound of carbon, hydrogen, and oxygen,
similar to a candle, as containing the same elements, though not in the
same proportion the proportions being as shewn in this table:
SUGAR.
Carbon, . . . . 72
_
Hydrogen, . . . 11 |
| 99
Oxygen, . . . . 88_|
This is, indeed, a very curious thing, which you can well remember, for
the oxygen and hydrogen are in exactly the proportions which form water,
so that sugar may be said to be compounded of 72 parts of carbon and 99
parts of water; and it is the carbon in the sugar that combines with the
oxygen carried in by the air in the process of respiration so making us
like candles producing these actions, warmth, and far more wonderful
results besides, for the sustenance of the system, by a most beautiful and
simple process. To make this still more striking, I will take a little
sugar; or, to hasten the experiment, I will use some syrup, which contains
about three-fourths of sugar and a little water. If I put a little oil of
vitriol on it, it takes away the water, and leaves the carbon in a black
mass. [The Lecturer mixed the two together.] You see how the carbon is
coming out, and before long we shall have a solid mass of charcoal, all of
which has come out of sugar. Sugar, as you know, is food, and here we have
absolutely a solid lump of carbon where you would not have expected it.
And if I make arrangements so as to oxidize the carbon of sugar, we shall
have a much more striking result Here is sugar, and I have here an
oxidizer a quicker one than the atmosphere; and so we shall oxidize this
fuel by a process different from respiration in its form, though not
different in its kind. It is the combustion of the carbon by the contact
of oxygen which the body has supplied to it. If I set this into action at
once, you will see combustion produced. Just what occurs in my
lungs taking in oxygen from another source, namely, the atmosphere takes
place here by a more rapid process.
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