Boiling

Collier's New Encyclopedia (1921)

in general, the change of a substance from the liquid to the gaseous state which takes place throughout the liquid. The boiling point, in science, is the point of degree of the thermometer at which any liquid boils. The boiling point of any liquid is always the same, if the physical conditions are the same. The boiling point of distilled water under pressure of 760 millimeters is 100° C., or 212° F. A difference of height of about 327 meters lowers the boiling point of water about 1° C., or 597 feet ascent lowers it 1° F. The boiling point of organic compounds is generally higher as the constitution is more complex. In a homologous series the boiling point rises about 19° for every additional CH₂ in normal alcohols, and 22° in the normal fatty acids, as ethylic alcohol, C₂H₂(OH) 78.4°; propylic alcohol, C₂H₂(OH) 97°; acetic acid, CH.CO.OH. 118°; propionic acid, C₂H.CO.OH 149.6 °. The secondary and tertiary alcohols have lower boiling points than the primary alcohols. The replacement of hydrogen in a hydrocarbon by chlorine, or by a radical, raises the boiling point, as benzene C6H6. 82°, chlorbenzene CoHsbl CH.bl. 135°, amidobenzene °. CH(NH2) 182 Liquids are not increased in heat after they once begin to boil; a fierce fire only makes them boil more rapidly. The following boiling points have been stated: Deg. Fahr. Mercury.. 662 Sulphuric acid. 610 Olive oil... 600 Phosphorus. Iodine. Naphtha.... 320 Oil of turpentine. 314 Water. Nitric acid. 210 Alcohol.. 173 Sulphuric ether. 113 Muriatic ether. In cookery, an important preliminary rule in boiling rests on the fact that water cannot be heated in an open vessel, or in one with the ordinary fitting lid of a cooking utensil, to a higher point than 212° F. When a vessel, then, has once begun to boil, a stronger fire than is just sufficient to keep it boiling will only evaporate, or waste, the water in steam, but will not cook the food any faster. For boiling fresh meat, 20 minutes is the allowance for each pound. The weather must also be considered; in frosty weather, or with very thick joints, extra 20 minutes should be given. Mutton loses in boiling, in 1 pound, 32 ounces; beef, in 1 pound, 4 ounces. Meat that has been salted and dried has its outer coat already sealed up; it requires, therefore, to be thoroughly washed, soaked for two hours in cold water, dried, and put to boil in cold water, gradually brought to the boiling point, and kept simmering for a time proportioned to the size of the piece. Before boiling poultry or fish, it is advisable to rub the outside skin with a cut lemon. This insures a snowy white appearance in the cooked food. Fish should be placed in cold water, in which a tablespoonful of salt and one of vinegar is mixed; should be gradually brought to the boiling point, and simmered carefully, lest the outer part should crack before the thick part is done. BOIS D'ARC (bwä-dark) (sometimes corrupted into BODOCK), also bow-wood, or osage orange (maclura aurantiaca), a tree belonging to the artocarpaceæ, suborder moraceæ, is a native of the southern United States. Its large, beautiful, orange-like fruits are scarcely eatable, but its spines make it useful as a hedge plant. Its wood is strong, and hard, and elastic, and hence was used by the Indians in the manufacture of their bows. BOIS DE BOULOGNE (bwä dè bölōn'), a wood near the gates on the W. of Paris, so named after the suburb Boulogne-sur-Seine. It is one of the pleasand antest Parisian holiday promenades a famous dueling ground.