American citizen. [volume] (Canton, Miss.) 1864-1890, 1874-10-17
FOOd and Work.

In a recent number the J0uy1,dt II
/ Chemistry explained how "a days work"
is measured in foot-tons, and its average
amount, including both the external
| work, or that performed in labor or
walking, and the INTERNAL work, or
that done by the organs of circulation,
respiration, digestion and other vital
processes. The former averages from
| 800 to 800 foottons, the higher figure
representing an exceedingly hard days
work. The latter may be reckoned, tax
ing the average of the best estimates, at
260 foot-tons. As might be expected, i.
is difficult to measure this internal work
with precision, and the estimates of
different Psychologists vary widely those
for the heart alone ranging from 122 to
2T foot-tons The former is the amount
| calculated by Haughton, who puts the re
spiratory movements at about l foot-tons
for the twenty-four hours, while others
have set them as high as Al foot-tOns. The
exact value is of no importance for our
present purpose. Taking the lowest
estimate, the internal work is no in
significant addition to the other labor
performed by the wonderful mechanism
of this body of ours.
Where does all this force come FROM
What keeps the machine going? The
idea of perpetual notion" or Il self
moving machine, is as absurd here rs in
any other department of mechanics. A
steam-engine may as well be expected to
run without its boiler and furnace as the
body without its equivalent for boiler
and furnace; and both alike must have
fuel to keep up their fires. We need not
dwell on this point, for the fact that the
food we eat maintains the heat of the
body, builds up and renews its muscular
tissues, and nourishes all its varied
energies has been Familiarity explained.
1t has been shown, moreover, that the
food is literally buIued to produce this
heat and force, and that the air we
breathe supports this combustion, which
is a process of oxidation, and dependent
on a constant supply of oxygen, precise
ly like the fire under the boiler of the
steam-cngine.
Now, we know that it is impossible to
calculate just how much work a pound
of coal burned in the furnace of an en-
CINE is capable of doing. The heat gen
Grated in the combustion is equivalent to
something more than II 100000 foot
pounds, and if none of it were wasted it
would actually do that amount of work.
In the steam engine, however, only
about tenth part of the energy stored
up in the fuel is realized as work.
May we not calculate in the same way
what work the food we eat, considered
rs fuel, is capable of doing, and compare
this result with the actual amount ac-
complished by it in the body? The
problem is somewhat more complicated
than in the case of the steam-engi CINE, but
several psychologists have tried their
hand AT it, and have attained reasonably
consistent results.
DR.. Franklin has determined the
" mechanical energy" of various kinds of
food, both when burnt in oxygen and
when consumed in the BODY The
amount is sometimes smaller in the lat
ter case than in the former, because the
combustion * nOSso complete. For cX-
ample, an ounce of albumen generates Il
certain amount of heat when burnt in
oxygen; but in the body some of its con
stituents are only partially oxidized, be
ing eXcreted in the form of urea. An
ounce of sugar, on the other hand is gen
orally all burnt up into carbonic acid
and water, and its actual energy in the
body, under whatever form it appears,
is equivalent to it. theoretical energy