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Boiling

Water boils at 212° F. (sea level), and simmers at 185° F. Slowly boiling water has the same temperature as rapidly boiling water, consequently is able to do the same work,—a fact often forgotten by the cook, who is too apt “to wood” the fire that water may boil vigorously.

Watery vapor and steam pass off from boiling water. Steam is invisible; watery vapor is visible, and is often miscalled steam. Cooking utensils commonly used admit the escape of watery vapor and steam; thereby much heat is lost if food is cooked in rapidly boiling water.

Water is boiled for two purposes: first, cooking of itself to destroy organic impurities; second, for cooking foods. Boiling water toughens and hardens albumen in eggs; toughens fibrin and dissolves tissues in meat; bursts starch-grains and softens cellulose in cereals and vegetables. Milk should never be allowed to boil. At boiling temperature (214° F.) the casein is slightly hardened, and the fat is rendered more difficult of digestion. Milk heated over boiling water, as in a double boiler, is called scalded milk, and reaches a temperature of 196° F. When foods are cooked over hot water the process is called steaming.