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.
People are made sick by drinking water from such a well.
37. Water.—Water is also a food, for it forms the most of our bodies. All food has water. Even dry crackers contain it.
38. Pure water.—Water in a well runs through the dirty earth, and yet is clear and pure. This is because sand holds back the dirt. But sometimes slops from the house, and water from the barn yard, soak through the soil until the sand is full. Then the well water will be dirty and poisonous. People are often made sick by drinking such water. In cities the dirt fills all the soil and spoils the water. So the water must be brought from the country in large pipes.
Water in lead pipes takes up some of the lead. Lead is a poison. You should let the water run off from a pipe a little while before you use it. Good water is clear and has no smell or taste. Dirty or yellow water, or water with a taste or smell, is not fit for use.