The Boston cooking-school cook book

it contains. Soft water is free from objectionable salts, and is preferable for household purposes. Hard water may be softened by boiling, or by the addition of a small amount of bicarbonate of soda (NaHCO_{3}). Water freezes at a temperature of 32° F., boils at 212° F.; when bubbles appear on the surface and burst, the boiling-point is reached. In high altitudes water boils at a lower temperature. From 32° to 65° F. water is termed cold; from 65° to 92° F., tepid; 92° to 100° F., warm; over that temperature, hot. Boiled water is freed from all organic impurities, and salts of lime are precipitated: it does not ferment, and is a valuable antiseptic. Hot water is more stimulating than cold, and is of use taken on an empty stomach, while at a temperature of from 60° to 95° F. it is used as an emetic; 90° F. being the most favorable temperature. Distilled water is chemically pure and is always used for medicinal purposes. It is flat and insipid to the taste, having been deprived of its atmospheric gases. There are many charged, carbonated, and mineral spring waters bottled and put on the market; many of these are used as agreeable table beverages. Examples: Soda Water, Apollinaris, Poland, Seltzer, and Vichy. Some contain minerals of medicinal value. Examples: Lithia, saline, and sulphur waters. SALTS Of all salts found in the body, the most abundant and valuable is sodium chloride (NaCl), common salt; it exists in all tissues, secretions, and fluids of the body, with the exception of enamel of the teeth. The amount found in food is not always sufficient; therefore salt is used as a condiment. It assists digestion, inasmuch as it furnishes chlorine for hydrochloric acid found in gastric juice. Common salt is obtained from evaporation of spring and sea-water, also from mines. Our supply of salt obtained by evaporation comes chiefly from Michigan and New York; mined salt from Louisiana and Kansas. Salt is a great preservative; advantage is taken of this in salting meat and fish. Other salts—lime, phosphorus, magnesia, potash, sulphur, and iron—are