one filled with water. Add five gallons of hot water to the mixture, stir well, and let it stand a few days, covered from dirt. It should be applied hot, for which purpose it can be kept in a kettle or portable furnace. The east end of the White House in Washington is embellished by this whitewash. It is recommended by the government for whitewashing light-houses.

A pint of this wash mixture, if properly applied, will cover one square yard, and will be almost as serviceable as paint for wood, brick, or stone, and is much cheaper than the cheapest paint.

Coloring matter may be added as desired. For cream color add yellow ochre; pearl or lead, add lampblack or ivory-black; fawn, add proportionately four pounds of umber to one pound of Indian red and one pound of common lampblack; common stone color, add proportionately four pounds raw umber to two pounds lampblack.

XII. HUMAN FOODS.

COMPOSITION OF HUMAN FOOD MATERIALS.* (ATWATER.)

Ordinary food materials, such as meat, fish, eggs, potatoes, wheat, etc., consist of

Refuse. As the bones of meat and fish, shells of shellfish, skin of potatoes, bran of wheat, etc.

Edible Portion.-As the flesh of meat and fish, the white and yolk of eggs, wheat flour, etc. The edible portion consists of water and nutritive ingredients or nutrients.

The principal kinds of nutritive ingredients are protein, fats, carbohydrates, and mineral matters.

The water, refuse, and salt of salted meat and fish are called non-nutrients. In comparing the values of different food materials for nourishment they are left out of account. Classes of Nutrients.—The following are familiar examples of compounds of each of the four principal classes of nutri

ents

PROTEIN.

Proteids.

Albuminoids, e.g., albumen (white of │eggs); casein (curd) of milk; myosin, the basis of muscle (lean meat); gluten of wheat, etc.

Gelatinoids, e.g., collagen of tendons; ossein of bones; which yield gelatin or glue, etc.

Meats and fish contain very small quantities of so-called extractives." They include kreatin and allied compounds, and are the chief ingredients of beef-tea and meat-extract. They contain nitrogen, and hence are commonly classed with protein.

Fats, e.g., fat of meat; fat (butter) of milk; olive-oil; oil of corn, wheat, etc.

Carbohydrates, e.g., sugar, starch, cellulose (woody fiber),

etc.

*Extracts from "Foods, Nutritive Value and Cost " (Farmers' Bulletin No. 23), and " Food and Diet" (U. S. Dept. of Agriculture Year book, 1894).

Mineral matters, e.g., phosphate of lime, sodium chlorid (common salt), etc.

The Fuel Value of Food.-Heat and muscular power are forms of force or energy. The energy is developed as the food is consumed in the body. It is measured in the laboratory by means of an apparatus called the calorimeter. The unit commonly used is the calorie, the amount of heat which would raise the temperature of a pound of water four degrees Fahrenheit.

Taking ordinary food materials as they come, the following general estimate has been made for the average amount of heat and energy in 1 pound of each of the classes of nutrients:

In I pound of protein....

In I pound of fats...

In I pound of carbohydrates....

Calories.

1,860

4,220

1,860

In other words, when we compare the nutrients in respect to their fuel values, their capacities for yielding heat and mechanical power, a pound of protein of lean meat or albumen of egg is just about equivalent to a pound of sugar or starch, and a little over two pounds of either would be required to equal a pound of the fat of meat or butter or the body fat.

Ways in which Food is Used in the Body.-Food supplies the wants of the body in several ways. It either

Is used to form the tissues and fluids of the body;

Is used to repair the wastes of tissues;

Is stored in the body for future consumption;

Is consumed as fuel, its potential energy being transformed into heat or muscular energy, or other forms of energy required by the body; or,

In being consumed protects tissues or other food from consumption.

Uses of the Different Classes of Nutrients.-Protein forms tissue (muscle, tendon, etc., and fat) and serves as fuel.

Fats form fatty tissue (not muscle, etc.) and serve as fuel. Carbohydrates are transformed into fat and serve as fuel.

All nutrients yield energy in form of heat and muscular strength.

In being themselves burned to yield energy the nutrients protect each other from being consumed. The protein and fats of body tissue are used like those of food. An important use of the carbohydrates and fats is to protect protein (muscle, etc.) from consumption.

Definition of Food and Food Economy.-The views thus presented lead to the following definitions: (1) Food is that which, taken into the body, builds tissues or yields energy; (2) the most healthful food is that which is best fitted to the wants of the user; (3) the cheapest food is that which furnishes the largest amount of nutriment at the least cost; (4) the best food is that which is both most healthful and cheapest.

We have, then, to consider the kinds and amounts of nutrients in different food materials, their digestibility, and the kinds and amounts needed for nourishment by people doing different kinds of work.

In general, the animal foods have the most of protein and fats, while the vegetable foods are rich in the carbohydrates, starch, and sugar. The lean meats and fish abound in protein. Cheese has so large a quantity of protein because it contains the casein of the milk. Among the vegetable foods, beans and peas have a high proportion of protein. The proportion in oatmeal is also large. In wheat it is moderate, and in corn meal it is rather small. The materials with the highest fuel value are those with the most fat, because the fuel value of the fat is, weight for weight, two and one-fourth times as great as that of either sugar, starch, or protein. Hence fat pork and butter lead the other materials in fuel value. The fat meats in general stand high in this respect. So also do the grains, flour, and meal, as they have large quantities of carbohydrates. Potatoes are quite low in the list in respect to fuel value as well as protein, principally because they are three-fourths water. For the same reason, milk, which is seven-eighths water, ranks low in respect to both protein and fuel value.

Dietaries and Dietary Standards.--As the outcome of a great deal of observation and experiment, nearly all in Europe, standards have been proposed for the amounts of nutrients and energy in the daily food required by different classes of people. Those of Prof. Voit, of Munich, Germany, are most commonly accepted by specialists in Europe. Voit's standard for a laboring man at moderately hard muscular work calls for about 0.25 pound of protein and quantities of carbohydrates and fats sufficient, with the protein, to yield 3050 calories of energy. Taking into account the more active life in the United States, and the fact that well nourished people of the working classes here eat more and do more work than in Europe, and in the belief that ample nourishment is necessary for doing the most and the best work, I have ventured to suggest a standard with 0.28 pound of protein and 3500 calories of energy for the man at moderate muscular work. (For list of dietary standards, see p. 175.)

Calculation of Daily Dietaries.—Due regard for health, strength, and purse requires that food shall supply enough protein to build tissue and enough fats and carbohydrates for fuel, and that it shall not be needlessly expensive.

On the basis of the standards for dietaries given on page 175, various combinations of food materials for daily dietaries may be made by calculations from the table, showing percentages of nutrients, etc., in food materials (p. 169). Thus if a dietary for a man at moderately hard muscular work is to be made up of round beefsteak, butter, potatoes, and bread, it may be calculated as follows: