=29. Milk=.--Milk is the best food known. It contains just enough water, albumin, fat, sugar, and minerals. Babies and young mammals live on milk alone. A man can live upon four quarts of milk a day. In sickness, milk is the very best food for men, as well as for babies. The albumin of milk becomes hard when the milk sours. This makes _cheese_. The fat of milk rises to the top. We call it _cream_. When cream is churned, the pure fat comes together in a lump. Pure fat of milk is called _butter_. Cheese and butter are both good foods. =30. Eggs.=--Eggs are also good food. The white of an egg is almost pure albumin. The yolk is albumin and fat. Eggs have no starch or sugar. They are not a perfect food, for some sugar must be eaten. But they can be quickly digested and they produce a great deal of strength. =31. Meat.=--Meat contains albumin and fat, but no sugar. Fish, oysters, and clams are like meat. They all make good food. Boys and girls should eat milk, eggs, and meat. These foods are the best to give strength to the body. Nearly all food from animals is more quickly digested and gives more strength than food from plants. =32. Bread.=--White bread is a food made from wheat. The wheat is ground to flour. Flour is mixed with water, and yeast is added. The yeast makes a gas, and the gas puffs up the wet flour and makes it full of holes. The holes make the bread _light_. Then bread is baked. Rye or corn meal makes good bread. Cake, biscuit, and pancakes are much like bread. Sometimes in place of yeast, baking powder is used to make the bread or cake light. =33. Meal.=--Oatmeal, corn meal, and cracked wheat and rice are sometimes boiled, and eaten with milk. Bread, biscuit, oatmeal, and corn meal are made from grain. All are very much alike. The cooking makes them look and taste different, but yet they are nearly the same. =34. Why we need grain food.=--All kinds of grain have much albumin, but only a little fat. But all have a great deal of starch. By digestion the starch becomes sugar. Grain is a good food because it has starch or sugar. Animal foods have no sugar, so we eat grain food with them. The two together make the most nourishing food. Potatoes have a great deal of starch and only a little albumin. They also are good food with meat. [Illustration: =A healthy man needs as much food as this every day.=] A person cannot live well upon plant food alone, for it has too much starch and sugar, and too little albumin and fat. We need nearly equal parts of albumin, fat, and sugar. A mixture of bread, meat, eggs, vegetables, and milk makes the best food. =35. Fruit.=--Fruit, like apples, peaches, and plums all have sugar. They taste good, and give us an appetite for other kinds of food. They have little albumin or fat. =36. Salt.=--There is enough mineral matter in all food, and we do not have to eat iron or lime or soda. But we do need some more salt. Even animals need salt. Salt makes food taste good, and helps its digestion.