The nutritive Elements of Food.--Many chemists have applied themselves in
recent years, to discover the exact percentage of nutriment contained in
different substances, and to determine the minimum nutriment on which
human life can be supported. The results are not very accordant, but
nevertheless a considerable approximation to truth has been arrived at.
It is now possible to tell whether a proposed diet has any great faults
of excess or deficiency, and how to remedy those faults. But it also must
be recollected that the stomach is an assimilating machine of limited
performance, and must be fed with food that it can digest; it is not
enough that the food should contain nutritious matter, if that matter
should be in an indigestible form. Burke and Wills perished from sheer
inability to digest the seeds upon which the Australian savages lived;
and Gardiner's party died of starvation in Tierra del Fuego, because they
could not digest the shell-fish which form a common article of diet of
the natives of that country. The question of diet must then be limited to
food that is perfectly digestible by the traveller. It remains to learn
how much nourishment is contained in different kinds of digestible food.
Dr. Smith has recently written an elaborate essay on this subject,
applying his inquiries chiefly to the food of the poor in England; but
for my more general purpose, as it is impossible to do justice to a large
and imperfectly understood subject, in the small space I can give to it,
it will be better that I should reprint the results given in my previous
edition. These are principally extracted from a remarkable paper by Dr.
Christison, inserted in the Bluebook Report of the Commission of Inquiry
on Crimean matters, in which the then faulty dietary of our soldiers was
discussed. It appears 1st, that a man of sedentary life can exist in
health on seventeen ounces per day of real nutriment; that a man engaged
in active life requires fully twenty-eight ounces per day; and, during
severe labour, he requires thirty ounces, or even more. 2ndly, that this
nutriment must consist of three-quarters, by weight, of one class of
nutritive principles, (C), and one quarter of another class of nutritive
principles, (N); 3rdly, that all the articles of common food admit of
being placed, as below, in a Table, by which we see at a glance how much
nutriment of class C, and how much of class N, is found in 100 parts,
gross weight of any of them. Thus, by a simple computation, the effective
value of a dietary may be ascertained. Class C, are the carboniferous
principles, that maintain respiration; Class N, are the nitrogenous
principles, that repair waste of tissue. N will partly replace C, but at
a great waste: C will not replace N.
A large number of diets such as those of various armies and navies, of
prisons and infirmaries, and of the ordinary diets of different classes
of people, have been examined by aid of this Table, with surprisingly
uniform results. But these diets chiefly refer to temperate climates; it
would therefore be a matter of great interest if travellers in distant
lands would accurately observe and note down the weight of their own
rations and those of the natives. It is a great desideratum to know the
lightest portable food suitable to different countries. Any such reports,
if carefully made and extending over a period of not less than two
months, would be very acceptable to me. To make them of any use, it is
necessary that every article consumed should be noted down; and that the
weight and state of health, at the beginning and at the end of the
period, should be compared.
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Table showing the quantity of Nutriment contained
in different articles of Diet.
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Articles of Diet .. C. N.
Total real
....................................................Nutri-
(Carboniferous.) (Nitrogenous) ment per cent.
of gross weight.
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Wheat Flour............. 71.25 .......... 16.25 ....... 87.5
Bread................... 51.5 .......... 10.5 ....... 62.0
Oatmeal................. 65.75 .......... 16.25 ........82.0
Pearl Barley............ 67.0 ........... 15.0 ........ 82.0
Peas.................... 55.5 ........... 24.5 ........ 80.0
Potatoes (preserved
potatoes are thor-
oughly dry)........ .. 24.5 ........... 2.5 ..........27.0
Carrots................ 8.5 ........... 1.5 ......... 10.0
Turnips.................. 5.7 ........... 0.3 ......... 6.0
Cabbage.................. 6.7 ........... 0.3 .......... 7.0
Lean of Beef and Mutton . - .......... 27.0 ......... 27.0
Fat of meat.............100.0 .......... - ....... 100.0
Average Beef and Mutton 15.0 ...........20.25 ........ 35.25
Bacon....................62.5 .......... 8.36 ........ 70.86
Skimmed-milk Cheese ..... 0.4 .......... 64.6 ......... 65.0
White Fish ............. - ........... 21.0 ......... 21.0
New Milk ............... 8.0 .......... 4.5 ......... 12.5
Skimmed Milk ........... 8.0 .......... 4.5 ......... 10.0
Butter-milk............. 1.0 .......... 6.0 ......... 7.0
Beef Tea, strong ........ - .......... 1.44 ......... 1.44
Beef Tea and Meat de-
coction of Broth ...... - .......... 0.72 ......... 0.72
Sugar...................100.0 ........... - ....... 100.0
Butter................. 100.0 ............ - ........ 100.0
Total (in Seden-
(tary life... 12.57 .......... 4.25 ........ 17 ounces.
Nutriment (in Active
(life......... 21.00 ......... 7.00 ........ 28 "
Required. (In Severe
(labour........22.50 ......... 7.50 ....... 30 "
As examples of the way in which the above Tables should be applied, I
will now give three dietaries, in which the quantity of real nutriment
has been calculated.