Then if we were to dry a slice of apple, it would shrink down into a little leathery shaving; and this, when thrown into the fire, would burn with a smudgy kind of flame, give off very little heat, and soon smoulder away. A piece of raw potato of the same size would shrink even more, but would give a hotter and cleaner flame. A leaf of cabbage, or a piece of beet-root, or four or five large strawberries would shrivel away in the drying almost to nothing and, if thoroughly dried, would disappear in a flash when thrown on the fire. These, then, except the potato, we should regard as Kindling foods. But it would take a large handful of lettuce leaves, or a big cup of beef-tea, or a good-sized bowl of soup, or a big cucumber, or a gallon of tea or coffee, to leave sufficient solid remains when completely dried, to make more than a flash when thrown into the fire. These, then, are Paper foods, with little fuel value. CHAPTER IV THE COAL FOODS Kinds of Coal Foods. There are many different kinds of Coal foods, such as pork, mutton, beef, bread, corn-cakes, bacon, potatoes, rice, sugar, cheese, butter, and so on. But when you come to look at them more closely, and to take them to pieces, or, as we say, analyze them, you will see that they all fall into three different kinds or classes: (1) _Proteins_, such as meat, milk, fish, eggs, cheese, etc. (2) _Starch-sugars_ (_carbohydrates_), found pure as laundry starch and as white sugar; also found, as starch, making up the bulk of wheat and other grains, and of potatoes, rice, peas; also found, as sugar, in honey, beet-roots, sugar cane, and the sap of maple trees. (3) _Fats_, found in fat meats, butter, oil, nuts, beeswax, etc. This whole class of Coal foods can be recognized by the fact that usually some one of them will form the staple, or main dish, of almost any regular meal, which is generally a combination of all three classes--a protein in the shape of meat; a starch-sugar in the form of bread, potatoes, or rice; and a fat in the form of butter in northern climates, or of olive oil in the tropics. PROTEINS, OR "MEATS" Proteins, the "First Foods." There are proteins, or "meats," both animal and vegetable; and no one can support life without protein in some form. This is because proteins alone contain sufficient amounts of the great element called _nitrogen_, which forms a large part of every portion of our bodies. This is why they are called proteins, meaning "first foods," or most necessary foods. Whatever we may live on in later life, we all began on a diet of liquid meat (milk), and could have survived and grown up on nothing else.