=How the Yeast Plant makes Alcohol.=--In the cake of yeast bought at the grocery there are millions of tiny plants, each shaped somewhat like a potato. This strange little plant will grow very rapidly when put into any sweet watery substance. It sends out a bud which grows larger and larger until in a half hour the bud is as large as the old plant. It may then break loose and grow other buds, just like the mother plant. When yeast grows, it changes the sugar or sweet part of the water into alcohol and a gas called carbon dioxide. It is this gas which makes beer foam and bubble when opened. All alcohol used in beer, porter, ale, wine, brandy, rum, gin, and whisky is made by yeast plants. [Illustration: FIG. 36.--Photograph of sprouted barley grains called malt.] =How Beer is Made.=--There is more beer used than any other alcoholic drink. It is cheap and is much weaker in alcohol than wine or whisky. Only about one twentieth part of beer is alcohol. [Illustration: FIG. 37.--Photograph of a spray of hops, which are used to flavor beer.] In making beer, a sweet watery mixture is first prepared by mashing sprouted barley grains in water. Barley or any other grain forms sugar as soon as it begins to grow. Yeast plants are added to the sweet mixture. By growing they change some of the sugar into alcohol. Hops are also put in to give the beer a fine flavor. After a time the clear liquid is separated from the barley grains and hops and put into tight casks and bottles. =The Making of Wine.=--Wine contains from two to four times as much alcohol as beer. Most of the wine is made in California, France, and Germany because grapes grow better in these countries than elsewhere. Wine may be made from the juice of any fruit, but the grape is generally used. [Illustration: FIG. 38.--The quantity of grapes required to make this glass full of wine.] The grapes after being picked are thrown into large tubs and crushed so that the juice runs out. The wild yeast always present on the grape skins begins to grow in the juice and change some of the sugar into alcohol. This work of the yeast lasts from one to eight weeks. At the end of that time, the grape juice has become a kind of poor wine, consisting of alcohol, water, grape flavor, and some acid. To make the wine good it must be drawn off into casks, where the yeast causes further changes during several weeks. It is then put into bottles, where it should remain about five years to get the right flavor. =Sherry= is a strong wine used in flavoring food, such as puddings and sauces. A few teaspoonfuls of this wine will make a child drunk. The wines made at home from elderberries, blackberries, and cherries contain alcohol which will do just as much harm as that in the purchased wines.