[Illustration:  Alcohol experiment.]

7.  The Alcohol Breath.—­You have doubtless heard that a person who is under the influence of liquor may be known by his breath.  His breath smells of alcohol.  This is because his lungs are trying to remove the alcohol from his blood as fast as possible, so as to prevent injury to the blood corpuscles and the tissues of the body.  It is the vapor of alcohol mixed with his breath that causes the odor.

8. You may have heard that sometimes men take such quantities of liquor that the breath becomes strong with the vapor of alcohol and takes fire when a light is brought near the mouth.  These stories are probably not true, although it sometimes happens that persons become diseased in such a way that the breath will take fire if it comes in contact with a light.  Alcohol may be a cause of this kind of disease.

9.  Making Alcohol.—­It may be that some of our young readers would like to find out for themselves that alcohol is really made by fermentation.  This may be done by an easy experiment.  You know that yeast will cause bread to “rise” or ferment.  As we have elsewhere learned, a little alcohol is formed in the fermentation of bread, but is driven off by the heat of the oven in baking, so that we do not take any of it into our stomachs when we eat the bread.  If we place a little baker’s yeast in sweetened water, it will cause it to ferment and produce alcohol.  To make alcohol, all we have to do is to place a little yeast and some sweetened water in a bottle and put it away in a warm place for a few hours until it has had time to ferment.  You will know when fermentation has taken place by the great number of small bubbles which appear.  When the liquid has fermented, you may prove that alcohol is present by means of the same experiment by which you found the alcohol in cider or wine. (See page 160.)

10. Alcohol is made from the sweet juices of fruits by simply allowing them to ferment.  Wine, as you know, is fermented grape juice.  Cider is fermented apple juice.  The strong alcoholic liquor obtained by distilling wine, cider, or any kind of fermented fruit juice, is known as brandy.

11.  How Beer is Made.—­Beer is made from grain of some sort.  The grain is first moistened and kept in a warm place for a few days until it begins to sprout.  The young plant needs sugar for its food; and so while the grain is sprouting, the starch in the grain is changed into sugar by a curious kind of digestion.  This, as you will remember, is the way in which the saliva acts upon starch.  So far no very great harm has been done, only sprouted grain, though very sweet, is not so good to eat as grain which has not sprouted.  Nature intends the sugar to be used as food for the little sproutlet; but the brewer wants it for another purpose, and he stops the growth of the plant by drying the grain in a hot room.

12. The next thing the brewer does is to grind the sprouted grain and soak it in water.  The water dissolves out the sugar.  Next he adds yeast to the sweet liquor and allows it to ferment, thus converting the sugar into alcohol.  Potatoes are sometimes treated in a similar way.