BOILING, 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 un der 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 or ganic compounds is generally higher as the constitution is more complex. In a homologous series the boiling point rises about 19° for every additional CH, in normal alcohols, and 22° in the normal fatty acids, as ethylic alcohol, CJI5(OH) 78.4°; propylic alcohol, C3117(OH) 97°; acetic acid, CIL.00.0H. 118°; propionic acid, C2H.s.00.0H 149.6°. The secondary and tertiary alcohols have lower boiling points than the primary alcohols. The replacement of hydrogen in a hydrocar bon by chlorine, or by a radical, raises the boiling point, as benzene C.H.. 82°, chlorbenzene C.115131. 135°, amidobenzene C.115(NH2) 182°.
Liquids are not increased in heat after they once begin to boil; a fierce fire only makes them boil more rapidly. The fol lowing boiling points have been stated: In cookery, an important preliminary rule in boiling rests on the fact that water cannot be heated in an open ves sel, 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 that 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 min utes 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. Mut ton loses in boiling, in 1 pound, 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 ad visable to rub the outside skin with a cut lemon. This insures a snowy white ap pearance in the cooked food. Fish should be placed in cold water, in which a table spoonful 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.