It shows, also, why it is far better to trust to useful domestic exercise at home than to send a young person out to walk for the mere purpose of exercise. Young girls can seldom be made to realize the value of health, and the need of exercise to secure it, so as to feel much interest in walking abroad, when they have no other object. But, if they are brought up to minister to the comfort and enjoyment of themselves and others, by performing domestic duties, they will constantly be interested and cheered in their exercise by the feeling of usefulness and the consciousness of having performed their duty.
There are few young persons, it is hoped, who are brought up with such miserable habits of selfishness and indolence that they can not be made to feel happier by the consciousness of being usefully employed. And those who have never been accustomed to think or care for any one but themselves, and who seem to feel little pleasure in making themselves useful, by wise and proper influences can often be gradually awakened to the new pleasure of benevolent exertion to promote the comfort and enjoyment of others. And the more this sacred and elevating kind of enjoyment is tasted, the greater is the relish induced. Other enjoyments often cloy; but the heavenly pleasure secured by virtuous industry and benevolence, while it satisfies at the time, awakens fresh desires for the continuance of so ennobling a good.
IX.
HEALTHFUL FOOD.
The person who decides what shall be the food and drink of a family, and the modes of its preparation, is the one who decides, to a greater or less extent, what shall be the health of that family. It is the opinion of most medical men, that intemperance in eating is one of the most fruitful of all causes of disease and death. If this be so, the woman who wisely adapts the food and cooking of her family to the laws of health removes one of the greatest risks which threatens the lives of those under her care. But, unfortunately, there is no other duty that has been involved in more doubt and perplexity. Were one to believe all that is said and written on this subject, the conclusion probably would be, that there is not one solitary article of food on God's earth which it is healthful to eat. Happily, however, there are general principles on this subject which, if understood and applied, will prove a safe guide to any woman of common sense; and it is the object of the following chapter to set forth these principles.
All material things on earth, whether solid, liquid, or gaseous, can be resolved into sixty-two simple substances, only fourteen of which are in the human body; and these, in certain proportions, in all mankind.
Thus, in a man weighing 154 lbs. are found, 111 lbs. oxygen gas, and 14 lbs. hydrogen gas, which, united, form water; 21 lbs. carbon; 3 lbs. 8 oz. nitrogen gas; 1 lb. 12 oz. 190 grs. phosphorus; 2 lbs. calcium, the chief ingredient of bones; 2 oz. fluorine; 2 oz. 219 grs. sulphur; 2 oz 47 grs. chlorine; 2 oz. 116 grs. sodium; 100 grs. iron; 290 grs. potassium; 12 grs. magnesium; and 2 grs. silicon.
These simple substances are constantly passing out of the body through the lungs, skin, and other excreting organs.
It is found that certain of these simple elements are used for one part of the body, and others for other parts, and this in certain regular proportions. Thus, carbon is the chief element of fat, and also supplies the fuel that combines with oxygen in the capillaries to produce animal heat. The nitrogen which we gain from our food and the air is the chief element of muscle; phosphorus is the chief element of brain and nerves; and calcium or lime is the hard portion of the bones. Iron is an important element of blood, and silicon supplies the hardest parts of the teeth, nails, and hair.
Water, which is composed of the two gases, oxygen and hydrogen, is the largest portion of the body, forming its fluids; there is four times as much of carbon as there is of nitrogen in the body; while there is only two per cent as much phosphorus as carbon. A man weighing one hundred and fifty-four pounds, who leads an active life, takes into his stomach daily from two to three pounds of solid food, and from five to six pounds of liquid. At the same time he takes into his lungs, daily, four or five thousand gallons of air. This amounts to three thousand pounds of nutriment received through stomach and lungs, and then expelled from the body, in one year; or about twenty times the man's own weight.