irk's
_Physiology_, p. 208.) These excreta are found to be carbon, nitrogen,
hydrogen, oxygen in great part, with some sulphur, phosphorus,
chlorine, sodium, etc. A summary is given (_ibid._, p. 432) of the
expenditure for twenty-four hours:

1. From the lungs:
Carbonic acid about 15,000 grains
Water " 5,000 "

2. From the skin:
Water " 11,500 "
Solid and gaseous matters " 250 "

3. From the kidneys:
Water " 23,000 "
Organic matter " 680 "
Saline bodies " 420 "

4. From the intestines:
Water " 2,000 "
Organic and mineral substances " 800 "

Total daily expenditure:
Solid matters " 17,150 "
Water " 49,500 "

Altogether about eight and a half pounds.

The credit side of the sheet is about as follows:

Solids (chemically dry foods) " 8,000 grains
Water, combined or otherwise 35,000 to 40,000 "
Oxygen, absorbed by the lungs " 13,000 "

Altogether about eight and a half pounds.

With the proper balance between the intake and the outgo, the functions
of the body will be carried on normally, but the balance must be a
proper one; that is, not only must the entire waste be repaired but the
correct proportions of one kind of food and another must be observed.
If all the elements needed are not furnished there can be no true
counterpoise.

How do we expend the energy? By the common wear-and-tear incident upon
all voluntary motion, all work and recreation, carrying on the internal
movements of digestion and respiration, by thinking, by loss of
temperature, by indulgence of any of our functions, and by any wrong
indulgence especially. Excessive use, voluntary or otherwise, will of
course diminish our total capital and cut short our lives. Could we
always maintain the right balance we need never die.

The importance of what has been said must now be clearly apparent. We
ought to be wisely interested in choosing the proper foods for our
daily needs and in having them properly prepared; we ought to know how
much carbohydrates we need, how much proteids, and regulate our diet
accordingly. The f