WATER AND BEVERAGES (A)
EXPERIMENT 6: THE DISSOLVING POWER OF WATER.—Put 1/2 teaspoonful of salt in a test tube, half fill it with water. Cover the mouth of the test tube with the thumb, then shake the tube. Do the contents become clear? Set the tube aside for a few minutes. Does the salt separate from the water?
When a solid substance, by mixing with water, disappears in the water and does not separate on standing, the solid substance is dissolved. The salt was therefore dissolved in cold water, or it may be said that salt is soluble in cold water, or that water is a solvent of salt.
SOLUTION AND DIGESTION.—The change of foods in the body from insoluble to a soluble form is one step in digestion. Foods are dissolved in the digestive juices of the mouth, stomach, and intestines. Some foods such as salt and certain sugars are readily dissolved. Other foods have to undergo changes before they will dissolve. Corn-starch, for example, does not dissolve in cold water. It must be changed into sugar (which is easily dissolved) in the process of digestion. Dissolving then is an important step in the process of digesting.
USE OF WATER IN THE BODY.—A person might live for a number of weeks without eating food, but he could live only a few days without drinking water. Water has many uses in the body.
(a) It is the greatest known solvent. Because of this property, water is extremely important in the processes of digestion. (See Solution and Digestion.)
(b) It is a great carrier. Water helps carry food materials to all parts of the body; and it aids in carrying off the wastes of the body.
(c) It assists in regulating the temperature of the body. Because water is present in blood, and blood flows from the warmer interior of the body to the colder exterior, the water aids in distributing the heat of the body. The evaporation of perspiration, which is largely composed of water, also aids in regulating body temperature.
It is thus readily seen that water is needed to keep the machinery of the body working smoothly. The uses of water may be summed up in the statement: Water aids in regulating body processes.
FOREIGN MATERIALS IN WATER.—Since water is such a ready solvent, it contains many foreign materials. In passing through the air and in flowing through the ground, it dissolves many substances. Some of these substances are harmless, while some contain disease bacteria and are dangerous. Well water is frequently contaminated. It is often not safe to use for drinking purposes unless boiled.
EXPERIMENT 7: PRESENCE OF GASES IN WATER.—Fill a beaker half full of water, and note its temperature. Heat the water, and observe the changes which take place. What appears on the sides and bottom of the beaker? What does water contain which is driven off by heat?
EXPERIMENT 8: SIMMERING AND BOILING OF WATER.—Continue to heat the water of Experiment 7 until the larger bubbles form and disappear at the surface of the water. Note the temperature. Continue to heat the water until bubbling occurs on the surface of the water. Note the temperature. What is indicated by the larger bubbles?
HEATING WATER.—When bubbling occurs below the surface, water is simmering. When the surface is in motion and steam is given off, water is boiling.
[Illustration: FIGURE 19—SCENE ON A TEA PLANTATION.]
The loss of gases makes boiled water taste flat or insipid. This flatness can be overcome somewhat by aerating the water after boiling, i.e. by pouring it from one vessel into another and thus mixing air with it.
TEA AND ITS SELECTION.—Tea shrubs grow in India, Ceylon, China, and Japan (see Figure 19). The buds and leaves of these shrubs are cut and dried and sold as tea.
In buying tea the size of the dried leaves should be noted. The smallest leaves are those which have grown nearest the tip of the twig and hence are the youngest. These make the choicest tea. The older and larger leaves make tea of less fine flavor. "Flowery Pekoe" and "Orange Pekoe" are choice India teas. These brands consist of the buds and youngest leaves.
Another point to consider in buying tea is its color. Tea leaves are either black or green. The chief difference between black and green tea is that black tea leaves are fermented after picking, while green are not. Tea leaves contain flavoring and stimulating materials and a substance called tannin (sometimes called tannic acid) which interferes with digestion. The presence of tannin in both black and green tea can be shown by the following:
EXPERIMENT 9: TANNIN IN TEA.—(a) Put 1/2 teaspoonful of black tea in a cup. Add 1/2 cupful of boiling water. Let it stand for 5 minutes, then strain the infusion.
(b) Repeat (a) substituting green tea for black.
(c) Into 2 test tubes put 1 teaspoonful of each kind of beverage. To each tube, add 1/2 teaspoonful of ferrous sulphate solution and let the tubes stand. If a black substance appears in the tubes, tannin is present. Which kind of beverage,—black or green tea,—shows the greater quantity of tannin?
By fermentation, tannin is changed into a less soluble form, so the beverage made from black tea contains less tannin than that made from green tea. Hence, black tea is preferable. It is, however, slightly more stimulating than green tea. Good black tea is grayish black in color, not dead black. "English Breakfast" is a black tea. It consists of a mixture of several black teas. "Oolong" is black in appearance, but has the flavor of green tea. This is because it is only semi-fermented. Teas grown in various countries have different flavors.
Tea is sometimes adulterated by using the leaves of other plants or by adding large leaves and stems. It is said the finest brands of tea do not reach this country.
MAKING THE BEVERAGE.—Because tea contains tannic acid, an earthen, enamel, china, or silver teapot should be used; a tin teapot should never be used. (See Suggestions for Cooking Fruits.) The ingredient in tea that gives it its odor and flavor is a volatile substance. Hence tea leaves should be kept in closely covered jars or cans.
Boiling water draws out substances which give the beverage its flavor and stimulating properties, while water below the boiling point only partially draws out these substances. If, however, the leaves are boiled or are allowed to remain in water for more than five minutes, much tannin is drawn out in the water. Therefore, never boil tea, but pour boiling water over it and in five minutes strain out the tea leaves.
TEA (proportion for one cupful)
1/4 to 1 teaspoonful black tea leaves 1 cupful freshly boiled water
Heat the teapot by pouring boiling water into it. Pour out the water and add the tea leaves. Pour over them the freshly boiled water. Place the teapot in a warm place to steep, and in 5 minutes strain out the tea leaves.
Teapots provided with perforated cups or with tea-balls (see Figure 20) for holding the tea leaves are most convenient, as the cup containing the leaves may easily be removed or the tea-ball can be drawn above the surface of the liquid after steeping the tea for 5 minutes. Or two teapots may be used, the beverage being strained from one teapot into the other.
The quantity of tea to be used varies with the strength of tea desired. If the leaves are closely rolled, less tea is required than if they are loosely folded.
Tea may be served with cream and sugar, or with lemon and sugar. The latter is called Russian Tea, and is often served with a preserved cherry.
In warm weather Iced Tea may be served. "Left over" tea may be utilized in this way, or hot tea may be cooled quickly by adding ice to it. While the latter method requires more ice, the tea is considered of a finer flavor. Iced Tea is served usually with sugar and lemon. Since sugar does not dissolve as readily in cold solutions as in hot (see Experiments 10 and 11) a sirup may be prepared for sweetening Iced Tea.
[Illustration: Courtesy of Manning, Bowman Co FIGURE 20.—TEA-BALL
TEAPOT.]
Even though tea is carefully selected and prepared it contains some tannin. This, as has been mentioned, is injurious. The stimulating material in tea also distresses some persons. Children, nervous persons, and those who suffer from constipation are advised not to drink tea.
TOASTED WAFERS AND CHEESE
Spread crackers or wafers with a small quantity of cheese. Season the cheese with a sprinkling of salt and paprika. Brown the wafers in the oven. When the cheese is melted, the wafers are ready to serve.
If thick crackers are used, they may be split open and the broken surface spread with cheese.