CITRIC ACID. This acid exists in nume rous fruits, particularly those of the orange tribe, such as the lemon and lime, either alone or with malic and other acids ; sugar, muci lage, and extractive are also present. It is colourless, inodorous, and extremely sour. When decomposed, it yields pyrocitric acid, and several other compounds. The citric acid is separated and purified on a large scale. Citric acid, when crystallised, has scarcely any odour, but a very distinct acid taste. It is so luble in cold and still more in warm water. It is used as a discharge iu calico printing.
Citric acid combines with ammonia, potash, soda, iron, zinc, copper, silver, lead, and other bases, to form salts.
Concentrated citric acid is somewhat caustic, but lemon juice is acid. To imitate the natural state, citric acid is only given largely diluted. In this state it proves a pleasant drink in fevers and ,diseases where the temperature of the body rises above the natural standard. According to Proussais, it agrees better than any other acid with the sto mach when affected with acute inOammation. It is not so pleasant as lemonade prepared from new fresh lemons; and, accerding to the statement of Sir G. Blanc, the solution of citric acid is not se efficacious in the prevention and cure of sea-scuryy as the recent lemon-juice.
This is attributable to the absence of the vola tile oil and the bitter principle of the rind, which are valuable adjuncts to the citric acid in its action on the stomach. The utility of lemon-juice in promoting, the digestion of ge latinous meats, such as veal and turtle, is well known. Fresh lemon juice may be preserved in bottles in the same way as ripe fruits, by boiling the bottles in which it is contained for half an hour, first placing them in cold water and gradually heating it, and, as soqn as the contents of the bottles have fallen to tho tem perature of the air, closing them hermetically. Where lemon juice so preserved, or fresh le mons, cannot be obtained by ships on long voyages, the dissolved citric acid, to which a Portion of alcoholic extract of lemon peel may lie added at the time of using, is some times used when apprehensions of scurvy are entertained.
Citric acid, as well as lemon juice, is much employed to decompose alkaline carbonates, forming therewith pleasant effervescing solu tions.