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CHAPTER II.

THE CHEMISTRY AND ECONOMY OF FOODS.*

It is an interesting fact that, although the cost of food makes up the larger part of the living expenses of ordinary people, even the most intelligent know less of the actual value of their food for fulfilling its purposes than of that of almost any other of the staple necessities of life. The man who buys a coat has generally a pretty fair idea as to the relation between its value and its cost, and if he is getting material to have it made, he knows about how much of each kind is wanted, and does not fall into the error of buying a great deal more cloth than he needs for the outside and using part of the excess for lining when cheaper material would do as well or better, nor does he try to economize by buying poor buttons and too little thread. But for his food he is very apt to select materials which furnish some of the nutritive ingredients at needlessly high cost, and in excessive amount, while they supply others in insufficient quantity and in very uneconomical ways.

If I succeed in making clear to you the points which I am here to urge, I believe you will be persuaded that not only our so-called laboring classes, but all who desire or are compelled to economize, would be greatly benefited by a better understanding of the principles on which the economy of food is based, and by the application of those principles in the purchase and use of their aliment.

I think a careful study of the subject will show that among the many ways in which our American habits of wastefulness manifest themselves, one of the worst is in the waste of food, and that this wastefulness is practiced by the poor as well as by the rich. It manifests itself in purchasing more than is needed, in using part of the excess to overload the alimentary organs and throwing the rest away, in using costly materials where less expensive ones would serve as well, in purchasing materials that are really dear but seem to be cheap, and in the false economy of using too little of one material and too much of another, and thus losing where there is an earnest attempt to save. And it is not only the loss to the purse from wrong selection of food in the market, but the loss to both purse and health by wrong keeping and cooking and using at home that is to be deplored, and ought to be avoided.

Then, too, we have to remember that it is the ignorant, and that means the poor, that suffer most from this improvidence, and when we consider still further the suffering that is endured from wrong use of food-and some of our wisest students of physiology and hygiene are persuaded that improper eating, and especially overeating, is a source of more disease than any other one thing; that what we may call the eating habit does, on the whole, more harm to health than the drinking habit-I think we

Paper read by Prof. W. O. Atwater, at the third annual session of the National Convention of Chiefs of the Bureaus of Labor Statistics, held at Boston, Mass., June 29th to July 1st, 1885.

shall be persuaded that the subject of the nature and uses of food is one worthy of our most careful consideration.

A pound of lean beef, round steak freed from fat, for instance, and a quart of milk, both contain about the same quantity, say a quarter of a pound, of actually nutritive material. But the pound of beef costs more than the quart of milk and it is worth more as a part of a day's supply of food. The nutritive materials or nutrients, as we call them, in the lean meat, though the same quantity as in the milk, are different in quality, and of greater nutritive value.

We have here an illustration of a fundamental fact in the economy of foods, namely, that the differences in the values of different foods depend upon both the kinds and the amounts of the nutritive material which they contain. If, then, we would understand the nutritive value of foods, we must know, first of all, what they are composed of. Knowing this, we must next consider what the several food ingredients do in the body; what is the special work which each one of the different nutrients has to perform in building up our bodies and in supplying their wants. When, in addition to all this, we know how much of each class of nutrients our bodies require and our foodmaterials contain we shall be in condition to economize our foods as we do the other necessaries of life.

Twenty five years ago, indeed I might say fifteen years ago, but comparatively little was known about these things, and for that matter our knowledge of them is still very far from complete. But, nevertheless, we do know to-day about how much of the different nutritive ingredients, or nutrients as they are called, our ordinary food materials contain, and we have a tolerably clear conception of the functions of these different ingredients in the nutrition of our bodies; and finally, a large amount of observation and experiment has told us about what proportions of the several classes of nutrients are required to meet the needs of people in different conditions of life.

LATER RESEARCH IN THE SCIENCE OF FOOD AND NUTRITION.

Among the numerous branches of biological research by no means the least interesting and important is the study of foods and nutrition. Within the past fifteen years especially, a very large amount of scientific labor has been devoted to the investigation of the composition of foods and the functions of their ingredients in the animal economy. Indeed, very few persons this side of the Atlantic have any just conception of the magnitude of this work and its result. And, though the most important problems are still unsolved, and must, because of their complexity, long remain so, yet enough has been done to give us a tolerably clear insight into the processes by which the food we eat supplies our bodily wants.

The bulk of our best definite knowledge of these matters comes from direct experiments, in which animals are supplied with food of various kinds, and the effects noted. The food, the excrement, solid and liquid, and in some cases the inhaled and exhaled air, are measured, weighed and analyzed. Many trials have been made with domestic animals-horses, oxen, cows, sheep, goats and swine-with dogs, rabbits, birds, and the like; and a large number also with human beings of both sexes and different ages. In the philosophical planning of the researches in the ingenuity manifested in devising apparatus; in accuracy, thoroughness, patience and persistence in the work, as well as in the distinguished genius of many of the workers, chemicophysiological science has assumed the highest rank among the sciences of our time; with the rest it has brought us where we can estimate the nutritive values of foods

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