Thompson divides foods into solids, semisolids, and liquids. Next, into fibrous, gelatinous, starchy, oleaginous, and albuminous. He speaks of eggs and milk as examples of complete foods which alone will support life; others, again, as starches, will not alone - absolutely alone - support life for a length of time. The sources of food are animal foods and vegetable foods. Animal foods are meats, poultry, fish, shell-fish, crustaceans, eggs, milk and its products, animal fats, and gelatin. Vegetable foods are the cereals, vegetables proper, fruits, sugars, and vegetable oils. Liebig's is the simplest chemical classification, the nitrogenous and the non-nitrogenous. The nitrogenous group are the tissue-builders or flesh-formers, as before stated. The non-nitrogenous group furnish the body with the fuel and keep up the animal heat, and are the force producers. The tissue-builders also produce some force and heat. There is some tissue-building matter in the vegetables, but not a very great deal. The outside coverings of the starch granules, for example, contain some nitrogen. Nitrogenous foods are also not absolutely nitrogenous, as they contain some fat and glycogen. Take rice as an example of tissue-building power in the vegetable. The Japanese people live largely on rice. Their prowess, as exhibited in the terrible war between them and the great Russian empire, shows well their great qualities as soldiers. The secret is probably here. They do not clean their rice as do the western nations. Much of the hull and such parts are left with the grain, and in these parts of the food, as eaten by them, is much nitrogenous matter - much tissue-building material - and hence the effective work those who eat it do. The same may be said of flour made from wheat and other grains. The white flour is deprived of some tissue-building material by bolting. This will be referred to again when speaking of bread as food.

The uses of food are to furnish the body with materials for growth and renewal, as before stated, and with power, much as fuel does for the steam-engine. The consumption of the fuel furnishes the power. The starches and sugars furnish much of the power to man. The original force is the heat of the sun; this is stored by the plants in the latent form of chemical compounds. The main source of power is oxidation, chiefly of carbon. Wherever it goes, or any waste product goes, it is not destroyed, it only changes its form; you cannot destroy matter. Take urea; it is merely matter of our food in a changed form, something like ashes from coal. This urea or other debris, if not removed from the body, blocks the system and prevents normal processes of oxidation, which must go on properly to give one good health. It is difficult to trace the final use of all foods in the body and tell how much goes to furnish power and how much to furnish heat, for tissue metabolism in its chemistry is complex. Egleston allows, of nutritive material for a healthy man for twenty-four hours, seven hundred grams in all, - four hundred grams of carbohydrates, one hundred and fifty grams of fats, and one hundred and fifty grams of proteids, these yielding three thousand six hundred and fifty calories or units of heat.

Water is to be looked upon as food, composing as it does 70 per cent. of the weight of our bodies, and much of it passes through the body unchanged. Withhold it, and life is impossible. As a remedy I am sure it is not half appreciated. Many persons do not drink water enough, and suffer accordingly, whether sick or well. Others, again, may take too much; and it is the duty of the physician to study each case and set his patient right on so important a matter. Of course much of the water we take goes in as part of our food, and this 50 to 60 per cent. of water in our solid foods must be taken into account. The salts, such as lime and magnesia, abound in the body, and they, with many others, have their uses in tissue-formation. Here the question of using distilled water comes in. By distilling water it is deprived of its salts and organic matters and is purified as to pathogenic and other germs. Some of the German authorities claim that by depriving water of its salts, which distillation does, we deprive it of those matters which afford proper nourishment to the protoplasm of the organic cell, and thus do harm to the economy. In proof of this it is stated that the German government has found that the use exclusively of distilled water on the vessels of the German navy has worked harm, and, to prevent this harm, has issued orders to add certain organic salts to the sailors' drinking-water to make up for their loss by distillation. On the other hand, it is argued that the use of distilled water is proper and healthful. As to the loss of the salts in the water by distillation, this is not a serious matter, as all of these salts are furnished in abundance in the solid foods we take. The hard water, the water that has not been distilled, furnishes too many of the salts which produce gout, the hardening of the arteries, etc, and thus old age is hastened, for hardened arteries are a natural condition in old age. By distilling water we destroy pathogenic and other germs, as has been before noted, and we thus avoid such diseases as typhoid fever, dysentery, cholera, etc. Boiling thirty minutes will also destroy most of these germs. Distilled water has high solvent power, and the use of it tends to warm and dilute the blood as we grow older, and to get rid of the salts which are liable to deposit in the tissues and do harm. These are the arguments used in the claim that distilled water tends to ward off the approach of old age and its infirmities, and they seem to be well taken.

Thompson, quoting from Von Pettenkofer and Voit, shows that during the performance of hard labor the consumption of albumin remains practically the same as during rest, whereas three and one-half times as much fat is consumed, and the amount of carbohydrates is the same. Hence, for hard laborers give plenty of fat pork, butter, oil, and such. A workingman will take from fifty to seventy-five ounces of solid food in twenty-four hours, and about the same amount of water by weight. The ration should contain one part of nitrogenous food to three and one-half parts of non-nitrogenous food. The average albuminous food gives about 16 per cent. of nitrogen. For a man weighing sixty-seven kilograms the daily allowance of food ranges from six to nine grains of carbon and .25 to .36 grain of nitrogen per kilogram of body weight. A kilogram is two pounds, three ounces, four and three-eighths drams avoirdupois.