A. Class Experiments. Eggs.
1. Weigh out a pound of eggs. How many average-sized eggs in a pound? Repeat with small eggs. With large eggs. Would it be fairer to sell eggs by the pound instead of by the dozen?
2. Boil an egg in a strong solution of cochineal for half an hour. Break open and examine. What property of the shell is shown? What problem does this present in the care of eggs?
3. Tests for freshness.
a. Place eggs in a ten per cent salt solution. What is the relation of the freshness of an egg to its specific gravity?
b. Roll up a large sheet of paper into a cylinder. Place an egg in one end and look through the other end. Hold in front of a strong light. What may a dark appearance indicate?
c. Note the feeling of the shell, rough or smooth.
d. Shake various eggs.
Are all these tests reliable with cold storage eggs?
B. Class Experiment.
1. Put a little white of an egg into a test tube and immerse the test tube in cool water above the level of the egg inside. Hold a thermometer in the egg white, and heat the water gradually, watching the egg carefully. As soon as it becomes opaque remove the tube from the water and note the temperature. Try some of the egg, and notice how tender it is. Replace the test tube with the rest of the egg white and heat as long as the temperature rises. Remove and compare with the first.
2. Cook an egg in boiling water for three minutes. Cook another by keeping it five minutes in water just below the boiling point (about 175° F.). Break and compare consistency.
3. Boil an egg for twenty minutes. Compare with an egg kept in water just below the boiling point for forty-five minutes.
C. Class Experiment. Boiling Eggs.
1. Place three eggs in three pints of boiling water. Cover closely to retain heat, but remove from flame. Remove: a. one egg in five minutes, b. one egg in seven minutes, c. one egg in ten minutes.
2. Give directions for cooking correctly: a. a soft-cooked egg, b. a medium-cooked egg, c. a hard-cooked egg.
D. Prepare Stuffed Eggs.
Cut a hard-cooked egg in halves; carefully remove the yolk. Season the yolk by mashing and mixing with it
1/4 tsp. vinegar 1 ssp. mustard
A pinch of salt
A few grains of paprika
Water, as everyone knows, exists in three states or conditions. It may be solid, in which case it is called ice; it may be liquid, and then it is really called water; or it may be a vapor, in which case it is spoken of as steam. The difference between these states is merely one of temperature. It takes heat to turn ice into water, and it takes heat to turn water into steam. Since water cannot, under ordinary circumstances, grow any hotter than its boiling point, cooking will not proceed any faster because the water is boiling fast instead of slow. All that is accomplished is the turning of more water into steam. If the object is the concentration of the material, then it is of course desirable to boil fast; but in most boiling it means merely a waste of heat. Occasionally the rapid motion is itself desirable, because it keeps the food from settling to the bottom of the pan and perhaps burning. The pressure cooker is a device for retaining the steam and so increasing the pressure that the water itself actually is hotter than the usual boiling point. Food can, of course, be cooked faster in it than in the usual covered kettle, because the temperature is really higher.
Water is used in more than one way in cooking. Sometimes it acts as a carrier of flavor, as when it is used to extract the flavor of tea or coffee; sometimes as a means of conveying heat to the food to be cooked. This is its use in boiling or steaming. At other times water is taken up into the food itself. In cooking rice, for example, there is much starch present but not enough water to hydrate it. This is the reason that rice cannot be put in an oven and baked as a potato can.
Water is composed of two gases, oxygen and hydrogen. It is true that some water is actually manufactured in the body by the oxidation of some of the hydrogen contained in food, but as the water we consume as such is never broken up in the body into these two gases, it is not necessary to consider further its chemical composition.
Although water is not capable of furnishing the body with energy, it is absolutely necessary to us. While people have proved that it is possible to go without food for weeks, it is impossible to live any length of time without water. The body itself is about two-thirds water. This means that there must be water to build up into body substance. Besides this, water has many important functions. For example, it moistens the digestive tract; makes it possible to swallow food; softens the food itself; mixes with the digestive ferments, and so enables them to act upon all parts of the food. It dissolves the food as it is digested and carries it through the lining of the digestive tract. Then, the blood is composed largely of water, as are all the other fluids of the body; so it is water that carries nourishment to all the different cells in the body.
Water in the blood circulating through the body acts as a distributor of heat, and, again, the evaporation of water as perspiration helps to regulate the heat of the body. It is water, too, that dissolves and carries away the wastes of the body. But these are only some of the important functions of water. It is probable that none of the chemical and physiological changes which go on in the body can take place except in the presence of water.
The body gives off from the lungs, skin, and kidneys about four and one-half pints of water daily. About one-sixth of this amount is the water that was spoken of as manufactured from the oxidation of food; the remaining amount must be taken into the body daily. Of course, a good deal of water is furnished by foods themselves. Soups and beverages obviously contain large amounts of water, but many other so-called solid foods, like potatoes, contain large amounts. It is usually said that a person needs about eight glasses of liquid a day.
At one time it was considered harmful to drink water with meals, for it was feared that the water would dilute the digestive juices to such an extent that they would fail to act upon the food. This notion is still popularly believed. Recent experiments, however, were tried to determine the truth of the matter. Healthy men were fed test meals, in some cases water being given and in others withheld. After a certain length of time, the contents of the stomach were examined to see how fast digestion had proceeded. In every case it was discovered that digestion took place more quickly if water had been given. We know now that the taking of water at meals is beneficial, stimulating digestion and not hindering it. What has been said is not in any way intended to imply that the washing down with water of poorly chewed food is anything but harmful. That is an entirely different question; nor is it intended to imply that the drinking of large quantities of very cold water may not have a different effect from the one described. Cold stops digestion, or slows it, and too much ice water at a meal may readily have this effect.
People who wish to grow thin are often told to go without water at meal times. The reason this is an aid is not that water itself is fattening, but because less is eaten if no liquid is taken. The same effect would be accomplished if we should in any other way lessen the amount eaten. Anyone going without water at meals should be sure to drink the needed amount of water between meals, for water is just as necessary to him as to anyone else.
Water is usually classified as surface and ground water. Rain water and water from streams and rivers belong to the first class. Well water and deep spring water belong to the second. Rain water is our purest water, if it is collected from a clean surface after the dust in the air has been washed out. This water, flowing along the ground or through it, dissolves or carries along with it many different substances. Water which has much mineral substance dissolved in it is called hard; this is the water that will not lather easily with soap. Hard water is, however, of two kinds. In one case there is present a soluble lime salt which precipitates if the water is boiled. This is the water which leaves a crust on the inside of a tea kettle. It is called temporarily hard because the water itself is softer after the boiling. Water containing salts of lime and magnesium which are unaffected by the boiling is called permanently hard. Permanently hard water may, however, be softened by the addition of such chemicals as soda, ammonia, and borax. Soft water is much the best for washing and also for cooking, but it is not so palatable as harder water. Water that is very hard is possibly not so good for us. If it can be softened by boiling, it may be cooled and used for drinking.
Water is a carrier of bacteria, and the most harmful water is not hard water, but water which contains harmful bacteria. There are many kinds of domestic filters which are supposed to remove the bacteria from the water. Most of them are not reliable and, in any event, need great care. They must be sterilized frequently or the water which goes through them will be found to contain more bacteria than it did before. If there is any reason to believe that the water is dangerous, it is much safer to sterilize the water by boiling it. All that is necessary is to bring the water to boiling and then cool it. Water which has been boiled tastes flat because it contains less air dissolved in it. The palatability can be increased by pouring the water back and forth from one pitcher to another so as again to dissolve air in it.
Freezing does not sterilize water. While in cities, at least, our water usually comes from a reservoir that is carefully protected from contamination, our ice supply may come from a private pond in which the water may be quite impure. Unless it is known that the water from which the ice was made was pure, the ice itself should not be put into beverages or foods. Instead, they can be set on ice to cool. So-called artificial ice is manufactured by freezing water in large tanks, the necessary cold temperature being often obtained by the evaporation of ammonia. Such ice is as pure as the water from which it is made.
U. S. Dept. of Agriculture. Bulletin 57. "Water Supply, Plumbing and Sewage Disposal for Country Houses." Ogden. "Rural Hygiene."
1. What diseases are most frequently carried by water?
2. Why is the water from shallow wells often dangerous?
3. How should such wells be protected?
4. Why is deep well water usually safer?
5. How is the question of sewage disposal bound up with the question of a safe water supply?