the bones may become firm and strong. Lack of iron salts in the food
impoverishes the coloring matter of the red blood corpuscles on which
they depend for their power of carrying oxygen to the tissues; anæmia
and other disorders of deficient oxidation result. The lack of
sufficient potash salts is a factor in producing scurvy, a condition
aggravated by the use of common salt. A diet of salt meat and starches
may cause it, with absence of fresh fruit and vegetables. Such
illustrations show the need of a well-balanced diet.

In order to understand the value of the various classes of food and
their relation to the body as force producers, tissue builders, etc.,
the following table may prove helpful:--

| | C.H.
| | Combustibles
| Nitrogen. | Calculated as
| | Carbon.
---------------------------------------------+-----------+--------------
Beef, uncooked | 3.00 | 11.00
Roast beef | 3.53 | 17.76
Calf's liver | 3.09 | 15.68
Foie-gras | 2.12 | 65.58
Sheep's kidneys | 2.66 | 12.13
Skate | 3.83 | 12.25
Cod, salted | 5.02 | 16.00
Herring, salted | 3.11 | 23.00
Herring, fresh | 1.83 | 21.00
Whiting | 2.41 | 9.00
Mackerel | 3.74 | 19.26
Sole | 1.91 | 12.25