(_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 a.s.sists 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 pa.s.sing 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_.
[Ill.u.s.tration: 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 j.a.pan (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_) subst.i.tuting 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 quant.i.ty 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-b.a.l.l.s (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 quant.i.ty 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.
[Ill.u.s.tration: 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 quant.i.ty 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.
QUESTIONS
By what means is flavor extracted from tea leaves?
How can the extraction of much tannic acid be avoided in tea?
Give the reason for using freshly boiled water for tea. (See Experiments 7 and 8.)
Which is the better kind of tea to use--black or green? Explain.
Why should tea be strained after steeping 5 minutes?
From your grocer learn the names and prices of two green and two black teas. From what countries do they come?
How many cupfuls in one pound of tea leaves? How many teaspoonfuls in a pound?
Determine the approximate number of wafers in a pound. Also estimate the quant.i.ty of cheese needed for one pound of wafers.
LESSON VIII
WATER AND BEVERAGES (B)
WATER AS A BEVERAGE.--Most foods contain water. Not only moist foods such as milk and watermelon, but solid foods such as potatoes and rice contain water. The water present in foods, however, is not sufficient for the needs of the body. It is necessary to use water as a beverage.
When one rises in the morning, it is well to drink one or two gla.s.sfuls of water. From one to two quarts of water,--either as plain water or in beverages,--should be taken each day. It used to be thought that water drinking during a meal was harmful. Scientific investigations have shown that this is a mistaken idea. Water may be drunk at mealtime. Indeed it has been found that it aids in the digestive processes, provided foods are not "rinsed down" with it and provided very cold water is not used.
WATER, A FOODSTUFF.--The body is nourished by food and there are many different kinds of food. Moreover, most foods are made up not of one substance, but of a number of materials. The chemical substances of which foods are composed are called _nutrients_ or _foodstuffs_ [Footnote 14: The difference between the scientific and popular meaning of the word foodstuffs should be noted. Foodstuffs is defined and used as a scientific term in this text.]. (Foodstuffs were formerly called _food principles.)_ A few foods contain but one foodstuff, some contain several foodstuffs, many contain all the foodstuffs.
[Ill.u.s.tration: Figure 21--Coffee Berries.]
Water is a foodstuff. There are other foodstuffs about which we shall study later. Each foodstuff has a certain function to perform in the body.
As explained in the previous lesson, water is a _body-regulating foodstuff._