Pure air, clothing, and cleanliness, are not the only things about which it is necessary to be particular in order to insure health. Without something for the oxygen taken into the lungs to consume, the air would do no good. Hence the amount of food used should be of the proper kind, in the proper quantities, and vary in kind and amount, according to the amount of oxygen inspired, and the quantity of heat necessary to be evolved to insure comfort and support life. We have already explained the evolution, of animal heat, and thus, the process of digestion and nutrition. We have seen that the inhabitants of cold climates require food rich in carbon, such as meat and oil, that those of the torrid climate require food containing but little carbon, and should feed more on fruits and vegetables, while in temperate regions a judicious intermixture of both is necessary. We will now mention the time required, as has been ascertained by experiment, for the digestion of some of the prominent articles of food.

Apples, sweet,

raw,

digested in

h.

m.

1.

50.

" sour, hard,

"

" "

2.

50.

Barley,

boiled,

" "

2.

Bass, striped, fresh,

broiled,

" "

3.

Beans, pod,

boiled,

" "

2.

30.

u green corn,

"

" "

3.

45.

Beef, fresh, lean, rare,

roasted,

" "

3.

" " steak,

broiled,

" "

3.

" old, hard, salted,

boiled,

" "

4.

15.

Beets,

"

" "

3.

45.

Bread, corn,

baked,

" "

3.

15.

" wheat, fresh,

"

" "

3.

30.

Butter,

melted,

" "

3.

30.

Cabbage,

raw,

" "

2.

30.

" with vinegar,

"

" "

2.

"

boiled,

" "

4.

30.

Cheese, old,

raw,

" "

3.

30.

Chicken,

fricasseed,

" "

2.

45.

Codfish, dry,

boiled,

" "

2.

Duck,

roasted,

" "

4.

Eggs, fresh,

hard boiled

" "

3.

30.

" "

soft boiled,

" "

3.

" "

raw,

" "

2.

Goose, wild,

roasted,

" "

2.

30.

Lamb,

broiled,

" "

2.

30.

h.

m.

Liver, beefs,

broiled,

digested in

2.

00.

Meat and vegetables,

hashed,

u

u

2.

30.

Milk,

u

a

u

2.

Mutton,

u

u

u

3.

Oysters,

raw,

u

a

2.

55.

u

stewed,

u

u

3.

30.

Pork,

roasted,

u

u

5.

15.

u

stewed.

u

u

3.

Potatoes, Irish,

boiled,

«

u

3.

30.

« U

roasted, baked, u

a

2.

30.

Rice,

boiled.

a

u

1.

Sago,

«

u

tt

1.

15.

Salmon, salted,

a

u

u

4.

Tapioca,

a

«

u

2.

Tripe,

a

a

u

1.

Trout, salmon,

a

a

u

1.

30.

Turkey,

a

a

it

2.

25.

Turnips,

a

a

u

3.

30.

Veal,

broiled,

a

u

4.

Venison steak,

u

a

u

1.

35.

Pork is exceedingly difficult of digestion, while mutton, beef, and venison are not only highly nutritious but easy of digestion.

Veal and lamb are nutritious, but not as easily digested, Poultry is generally easy of digestion, and when young and tender, suitable to invalids.

For invalids who are not able to digest meat and yet require its strength, "beef tea" is a very excellent preparation. Its ordinary way of preparing it is, to place some fresh meat cut in small pieces into a bottle with the necessary amount of water, cork it up and then place the bottle in boiling water where it can remain until the juice is extracted from the meat.

Liebig gives the following formula, which is still better. "Take a half a pound of fresh beef or chicken, chop it finely, and mix it well with a pint and a half of ice cold water. to which has been added four drops of pure Hydrochloric-acid (Muriatic-acid) and a teaspoon-ful of common salt. After standing for one hour, the whole is thrown upon a hair-sieve and suffered to drain without any pressure. The first cloudy droppings are returned to the sieve until it flows quite clearly. A half pint is then thrown in, in small portions upon the residue in the sieve."

This liquid extract of flesh must be administered to the patient cold and should be kept continually cold, as when heated it becomes cloudy, and gives rise to a thick deposit of flesh albumen and haematin, and is liable to turn sour. External ice cooling removes the difficulty completely.

Eggs and oysters are nutritious, and if not cooked too much, easy of digestion. Rice is nutritious and easy of digestion, as well as sago, arrow-root, tapioca, and farina. The potato is more digestible when roasted or baked than when boiled. Fruits of all kinds are not generally nutritious, although they are refreshing and wholesome. They should be eaten, however, in the fore-part of the day, or at any rate not in the evening. As it regards the use of coffee, no particular directions can be given. It is highly injurious to some, while others can use it, not too strong, with plenty of milk, with entire safety. It is strictly prohibited in almost every form of disease, especially when taking medicine. Tea is subject to the same objections as coffee, although black tea can generally be used with safety, while green tea is decidedly objectionable. Cold water is a very excellent substitute for either.

Chocolate is a pleasant drink, preferable to either tea or coffee, when there is no disease of the stomach or abdomen. Milk is highly nutritious, but to persons of plethoric habit it had better be in a great measure avoided.

Exercise is highly important to the health of the organs and the process of digestion. But vigorous violent exercise should not be indulged in immediately before or immediately after a meal, for in either case the harm would be far greater than any benefit which might result. Exercise should be active, to a certain extent in the out-door air, and as regular as possible. Violent fatigue should of course be avoided, the exercise being gradually increased as the strength will bear it. Persons accustomed to a sedentary life should at certain hours exercise the whole system. Among children playing at ball, dancing, or jumping the rope, are pleasant recreations, while among adults, riding, swimming, walking, fencing and dumb-bells are equally serviceable. In this way all the organs are kept active and full of vitality, the mind also is clear and capable of greater labor, and the body more robust, better proportioned and capable of greater exertion.