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Domestic Economy, Hygiene, Dietetics.

AIR.

The common air is a fluid composed mainly of two gases, in certain proportions; namely, oxygen as twenty and nitrogen as eighty parts in a hundred, with a very minute addition of carbonic acid gas. Such is air in its pure and right state, and such is the state in which we require it for respiration. When it is loaded with any admixture of a different kind, or its natural proportions are in any way deranged, it cannot be breathed without producing injurious results. We also require what is apt to appear a large quantity of this element of healthy existence. The lungs of a healthy full-grown man will inhale the bulk of twenty cubic inches at every inspiration, and he will use no less than fifty-seven hogsheads in twenty-four hours.

Now, there are various circumstances which tend to surround us at times with vitiated air, and which must accordingly be guarded against. That first calling for attention is the miasma or noxious quality imparted to the air in certain districts by stagnant water and decaying vegetable matter. It is now generally acknowledged that this noxious quality is in reality a subtle poison, which acts on the human system through the medium of the lungs, producing fevers and other epidemics.

bination just alluded to. Now, carbonic acid gas, in a larger proportion than that in which it is found in the atmosphere, is noxious. The volume of it expired by the lungs, if free to mingle with the air at large, will do no harm; but, if breathed out into a close room, it will render the air unfit for being again breathed. Suppose an individual to be shut up in an airtight box: each breath he emits throws a certain quantity of carbonic acid gas into the air filling the box; the air is thus vitiated, and every successive inspiration is composed of worse and worse materials, till at length the oxygen is so much exhausted that it is insufficient for the support of life. He would then be sensible of a great difficulty in breathing, and in a little time longer he would die.

Most rooms in which human beings live are not strictly close. The chimney and the chinks of the doors and windows generally allow of a communication to a certain extent with the outer air, so that it rarely happens that great immediate inconvenience is experienced in ordinary apartments from want of fresh air. But it is at the same time quite certain that, in all ordinary apartments where human beings are assembled, the air unavoidably becomes considerably vitiated, for in such a situation there cannot be a sufficiently ready or copious supply of oxygen to make up for that which has been consumed, and the carbonic acid gas will be constantly accumulating. This is particularly the case in bedrooms, and in theaters, churches, and schools.

is done. These are generally smaller than other rooms, and they are usually kept closed during the whole night. The result of sleeping in such a room is very injurious. A common fire, from the draught which it produces, is very serviceable in ventilating rooms, but it is at best a defective means of doing so. draught which it creates generally sweeps along near the floor between the door and the fire, leaving all above the level of the chimneypiece unpurified. Yet scarcely any other arrangement is anywhere made for the purpose of changing the air in ordinary rooms.

The

Putrid matter of all kinds is another conspicuous source of noxious effluvia. The filth collected in ill-regulated towns, ill-managed drains, collections of decaying animal substances placed too near or within private dwellings, are notable for their effects in vitiating Perhaps it is in bedrooms that most harm the atmosphere, and generating disease in those exposed to them. In this case, also, it is a poison diffused abroad through the air which acts so injuriously on the human frame. The human subject tends to vitiate the atmosphere for itself, by the effect which it produces on the air which it breathes. Our breath, when we draw it in, consists of the ingredients formerly mentioned; but it is in a very different state when we part with it. On passing into our lungs the oxygen, forming the lesser ingredient, enters into combination with the carbon of the venous blood (or blood which has already performed its round through the body); in this process about two fifths of the oxygen is abstracted and sent into the blood, only the remaining three fifths being expired, along with the nitrogen nearly as it was before. In place of the oxygen consumed, there is expired an equal volume of carbonic acid gas, such gas being a result of the process of com

FOOD.

A food is a substance which, when introduced into the body, supplies material which renews some structure or maintains some vital process; and it is distinguished from a medicine in that the latter modifies some vital action, but does not supply the material which

sustains such action.

tain it can efficiently produce flesh or repair wasted tissue. So important is this distinction, in fact, that one of the divisions of food most generally recognized by physiologists is into nitrogenous and non-nitrogenous, or, as Liebig termed them, the flesh-forming and the heat-producing. Both kinds are essential to the maintenance of life, and it is because vegetables as a whole are deficient in nitrogen that the highest degree of bodily vigor cannot be kept up by them alone.

It is understood that the structures of the body are in a state of continual change, so that atoms which are present at one hour may be gone the next, and when gone the structures will be so far wasted, unless the process of waste be accompanied by renewal. But the renewing substance must be of the same nature as that wasted, so that bone shall be re

It is essential to the idea of a food that it support or increase vital actions; whilst medicines usually may lessen, increase, or otherwise modify some of them. "Foods are derived," says Dr. Edward Smith, "from all the great divisions of nature and natural products, as earth, water, and air, solids, liquids, and gases; and from substances which are living and organic, or inanimate and inorganic. The popular notion of food as a solid substance derived from animals and vegetables, whilst comprehensive is too exclusive, since the water which we drink, the air which we breathe, and certain minerals found in the substance of the earth, are, adopting the definition given, of no less importance as foods. It is, however, of great interest to note how frequently all these are combined in one food, and how closely united are substances which seem to be widely separated. Thus water and min-newed by the constituent elements of bone, erals are found in both flesh and vegetables, whilst one or both of the components parts of the air, viz., oxygen and nitrogen, are distributed through every kind of food which is alone capable of sustaining life. Hence, not only may we add food to food to supply the waste of the body, but we may within certain limits substitute one for another as our appetites or wants demand. . Further, there seems to be an indissoluble bond existing between all the sources of food. There are the same classes of elements in flesh as in flour, and the same in animals as in vegetables.

and flesh by those of flesh. This is the duty assigned to food, to supply to each part of the body the very same kind of material that it lost by waste. As foods must have the same composition as the body, or supply some such other materials as can be transformed into the substances of the body, it is desirable to gain a general idea of what these substances are. The following is a summary of the principal materials of which the body is composed:

Flesh, in its fresh state, contains water, fat, fibrin, albumen, besides compounds of lime, phosphorus, soda, potash, magnesia, silica, and iron, and certain extractives, whose nature is unknown. Blood has a composition similar in elements to that of flesh.

Bone is composed of cartilage, fat, and salts of lime, magnesia, soda, and potash, combined with phosphoric and other acids.

Cartilage consists of chondrin, from which gelatine is formed, with salts of soda, potash, lime, phosphorus, magnesia, sulphur, and iron. The brain is composed of water, albumen, fat (so-called), phosphoric acid, osmazome, and salts.

The vegetable draws water and minerals from the soil, whilst it absorbs and incorporates the air in its own growth, and is then eaten to sustain the life of animals, so that animals gain the substances which vegetables first acquired. But in completing the circle the vegetable receives from the animal the air (carbonic acid) which was thrown out in respiration, and lives and grows upon it; and at length the animal itself in whole or in part, and the refuse which it daily throws off, become the food of the vegetable. Even the very bones of an animal are by the aid of nature or man made to increase the growth of vegetables and really to enter into their structure; and being again eaten, animals may be said to eat their own bones, and live on their own flesh.' It will be seen from this that animal and vegetable foods contain precisely the same elements though in different combinations. At the same time they differ sufficiently to make a due proportion of each necessary to perfect nutrition. One sterling point of difference is, that nitrogen constitutes a much larger percentage of animal bodies than of vegetables. Hence, it is requisite that the body should Nitrogen is one of the most important ele- be provided with salts of potash, soda, lime, ments of food; only such substances as con- magnesia, sulphur, iron, and manganese, as

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The liver consists of water, fat, and albumen, with phosphoric and other acids, in conjunction with soda, lime, potash, and iron.

The lungs are formed of a substance called connective tissue, from which gelatine is formed by prolonged boiling, albumen, a substance analogous to casein, various fatty and organic acids, with salts of soda and iron, and water.

Bile consists of water, fat, resin, sugar, fatty and organic acids, cholesterin, and salts of potash, soda, and iron.

well as sulphuric, hydrochloric, phosphoric, | direct relation to the prevailing temperature. and fluoric acids and water; also, nearly all In cold regions man requires such food as not the fat which it consumes daily, and probably only supplies him with nutriment, but also all the nitrogenous substances which it re- with heat; as oil, butter, fat, sugar, and other quires and which are closely allied in compo- substances in which carbonaceous elements sition, as albumen, fibrin, etc. "So great an predominate. In warm countries, on the conarray of mysterious substances," says Dr. trary, it is one of the most essential conditions Smith, "might well prevent us from feeding of good health, that his food should be as litourselves or others if the selection of food de- tle heating as possible. In our own climate pended solely upon our knowledge or judg- this law holds good as between summer and ment; but it is not so, for, independently of winter; in the latter season, plenty of lean the aid derived from our appetites, there is the meat, butter, potatoes, eggs, sugar, and great advantage of having foods which con- similar food are necessary to keep the animal tain a proportion of nearly all these elements; machine in working order, while in summer and combinations of foods have been effected the diet should consist chiefly of those subby experience which protect even the most stances of which nitrogenous or flesh-forming ignorant from evil consequences. Thus flesh, elements compose the largest part. There is or the muscular tissue of animals, contains probably no other cause so fruitful in producprecisely the elements which are required in ing the dyspepsia and similar diseases of which our flesh-formers, and, only limited by quan- Americans, as a nation, are in a peculiar degree tity, our heat-generators also; and life may be the victims as the neglect to harmonize the maintained for very lengthy periods upon ani- food with the changing seasons. mal food and water. Seeing, moreover, that the source of flesh in animals which are used as food, is of vegetable origin, it follows that vegetables should contain the same elements as flesh, and it is a fact of great interest that in vegetables we have food elements closely analogous to those contained in the flesh of animals. Thus, in addition to water and salts, common to both, there is vegetable chondrin, vegetable albumen, vegetable fibrin, and vegetable casein, all having a composition almost identical with animal albumen, fibrin, chondrin and casein." The articles containing most of the three articles needed generally in the body are as follows: for fat and heat-making - butter, lard, sugar and molasses; for flesh or muscle-forming-lean meat, cheese, peas, beans, and lean fishes; for brain and nervesshell fish, lean meats, pease, beans, and very active birds and fishes, who live chiefly on food in which phosphorus abounds. meat diet, the fat supplies the carbon for keeping up the heat of the body, and the lean furnishes nutriment for the muscles, brain, and nerves. Green vegetables, fruits, and berries furnish additional supplies of the acids, the salts, and water needed.

In a

Kinds of Food. The simplest and most powerful agent in determining the character of our food is climate. In cold countries the requirements of man are very different from those felt in the tropics, and from the Esquimaux, who, according to Dr. Kane, will drink ten or twelve gallons of train oil in a day, to the Peruvians and other tropical nations for whom the banana suffices for nearly all seasons of the year, there are various gradations in which the constituents of the diet bear a very

The next most important question in determining the character of our food is that of its digestibility; and it must be borne in mind that the nutritive value and the digestibility of food have no necessary relation to each other. A food may have a very high nutritive value and yet be so indigestible as to be practically useless, and on the other hand it may be very easily digested and worth little or nothing for nutrition. No general rules as to the digestibility of different foods can be laid down, because it depends very largely upon individual habits and conditions. Persons who have a strong constitution, and take sufficient exercise, may eat almost anything with apparent impunity; but young children who are forming their constitutions, and persons who are delicate, and who take but little exercise, are very dependent for health upon a proper selection of food. As a general thing, when the body requires a given kind of diet, specially demanded by brain, lungs, or muscles, the appetite will crave that food until the necessary amount is secured. If the food in which the needed aliment abounds be not supplied, other food will be taken in larger quantities than needed until that amount is gained; for all kinds of food have supplies for every part of the body, though in different proportions. Thus, for example, if the muscles are worked a great deal, food in which nitrogen abounds is required, and the appetite will remain unappeased until the requisite amount of nitrogen is secured. Should food be taken which has not the requisite quantity, the consequence will be that the vital powers will be needlessly taxed to throw off the excess. There are other kinds of food which are not only nourishing

but stimulating, so that they quicken the functions of the organs on which they operate; the condiments used in cookery, such as pepper, mustard, and spices, are of this nature. There are certain states of the system in which these stimulants may be beneficial and even necessary; but persons in perfect health, and especially young children, never receive any benefit from such food, and just in proportion as condiments operate to quicken the action of the internal organs, they tend to wear down their powers. The same observation applies to the use of wines and other spirituous and malt liquors. Under certain conditions where the vital powers are low, they are a highly important addition to ordinary food; but when used habitually, their temporary stimulation is gained at the expense of permanently weakening the digestive organs which finally refuse to perform their work without some such external aid. It follows from the above that the requirements of food in each case may in a normal condition of things be left to the individual taste, to be selected and prepared as is indicated by experience to be most appropriate.

Nutritiousness of Food. The following table from authentic sources shows the ascertained percentage of nutriment in the common articles of table consumption:

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raw

raw

roasted

roasted

boiled

boiled

Lamb, fresh..

broiled

Hash, meat and vegetables.

warmed

Beans, pod..

boiled

Cake, sponge...

baked

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Parsnips...

boiled

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Potatoes, Irish.

roasted

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Apricots...

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Beans, dry

boiled

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181888

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Pork steak..

Mutton, fresh.

2 15 Bread, corn.

Carrot, orange.

Cheese, old, strong.

5 15 Soup, mutton..

raw

raw

10

raw

29

roast boiled boiled baked fried boiled

13

Oyster soup,

Bread, wheat, fresh.

79

Turnips, flat...

20

raw

12

Venison

boiled fried broiled

4

25

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Potatoes, Irish.

Eggs, fresh...

Green corn and beans..

Beets'..

Salmon, salted.

Beef

Veal, fresh.

Composition of Various Articles of the absorbents take portions of it into the cirFood. In 100 parts.

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Fat.

Salts.

73.3 2.9

66.8 2.1
2.4 2.0

2.5 3.3

29.8 4.4

3.6 5.1

culatory system, and all the various bodily functions dependent on the blood are thus gradually and imperceptibly injured. Very often, indeed, intemperance in eating produces immediate results, such as colic, headache, indigestion, and vertigo; but the more common result is the gradual undermining of all parts of the human frame, shortening life by thus weakening the constitution.

As to the hours of meals these are of no importance provided they are regular and come at regular intervals. This interval should never be less than five hours, as the stomach requires at least three hours to digest its sup83.0 2.0 ply of food, and not less than two hours should be allowed it for rest and recuperation.

1 1.7

0.7 0.8
0.5 0.7

31.1 4.5

Eating between meals is a most injurious 24.3 5.4 practice, the source in children, especially, of endless stomachic disorders. It may be well to give children under ten years of age one more meal during the day than the three which adults in this country usually allow themselves; but these, as we have said above, should be at 2.9 1.0 regular times and with stated intervals between them.

6.3 4.9 8.1 1.7 2.8 26.7 1.8 13.8 1.3 10.5 1.5 1.6 39.7 1.3

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0.2

Biscuit...

15.6

1.3

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0.2 1.6

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0.4

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5.2

Milk, skimmed.

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Potatoes..

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Mutton, fat..

Mutton, lean.

Oatmeal.

Parsnips
Pease..

Pork, fat..

Veal..

Wheat flour.

13.2
1.2
165

4.1 3.0
15.45 3.0

3.49 .21
3.9 0.8

1.8 0.8

2.0 2.1 2.5

5.1 2.1 10.8 66.3 4.2

48.9 2.3

0.2 0.7
3.8 1.2

over.

After taking a full meal, it is very important to health that no great bodily or mental 31.1 3.5 exertion be made till the labor of digestion is Muscular exertion draws the blood to the muscles, and brain work draws it to the head; and in consequence of this the stomach loses the supply which is necessary to it when performing its office, the adequate supply of gastric juice is not afforded, and indigestion is the result. The heaviness which is felt after a full meal is a sure indication of the need of quiet; when the meal is moderate, the process of digestion will be sufficiently advanced in an hour, or an hour and a half, to justify the resumption of bodily or mental labor.

0.7 0.5
2.0 1.8

5.5 1.4

16. 2.4
0.6

15.8 4.7
2.0 1.7

Quantity of Food. With regard to the quantity of food to be taken, this also depends The Diet of Brain Workers. It has upon individual conditions and cannot be long been one of the pet theories of popular formed into a general rule. Where hunger is physiology, that fish and other substances comfelt it may safely be assumed that when the posed largely of phosphorus, are the most aphunger has been fully appeased sufficient food propriate diet for brain workers; but it is now has entered the stomach. Such are the cir- conceded that the best food for the brain is cumstances of civilized life, however, that in that which best nourishes the whole body with most cases hunger is a very rare sensation; special reference to the nervous system, viz. : and food is prepared and eaten more to gratify fat and lean meat, eggs, milk, and the cereals. the palate than because nature demands it. Discussing this point in a recent treatise, Dr. On this point each individual is and must be George M. Beard says: "The diet of brain a law unto himself, and we can only point out workers should be of a large variety, delicately the consequences of eating a larger quantity served, abundantly nutritious, of which fresh than is needed. When too great a supply of meat, lean and fat, should be a prominent food is put into the stomach, the gastric juice constituent. In vacations, or whenever it is only dissolves that portion of it which the desired to rest the brain, fish may, to a certain wants of the system demand; most of the re-extent, take the place of meat. We shoul mainder is ejected in an unprepared state, select those articles that are most agreeable to

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