Acidum Citricum. 3HO,C12H5O11 +HO.

It exists largely in the juice of the Lemon, Lime, and Orange; and is also found in smaller quantities in the juice of the Grape, Tamarind, Gooseberry, Currant, and other fruits.

Med. Prop. and Action. Refrigerant and anti-scorbutic. Citric Acid, observes Dr. Thompson, as prepared by the hand of nature in the juice of the lemon, orange, &c., is more grateful than in its uncombined state, - a fact which is quickly perceived by patients in fever. When simply diluted with water, Citric Acid constitutes a most serviceable and agreeable beverage in fevers, and in those of a typhoid character. This is rendered more grateful and refreshing by using water impregnated with carbonic acid gas instead of common water. In the ordinary condition of the stomach, Citric Acid, either pure or combined, does not weaken the stomach; and in some irritable states of that organ, characterised by a sensation of heat, painful digestion, an unpleasant taste in the mouth, and a disgust for food, it removes these symptoms, and proves decidedly beneficial; but, on the other hand, when the stomach is highly irritable, an 1 its nervous susceptibility great, Lemon-juice, or Citric Acid, even when largely diluted, causes heat, uneasiness, pain, and not un-frequently obstinate vomiting. Nevertheless, as M. Broussais has remarked, the Citric is that acid which the stomach supports the best when suffering from inflammation. The citrates of Potash and Ammonia are refrigerant and slightly diuretic; those of Soda and Magnesiapurgative. The following table shows the equivalents required for making effervescing draughts: -

* Lancet, Oct. 15th, 1853.

Phlegmas. Chron. t. iii. p. 254. R

grs.

grs.

20 of

Carb. of Soda

=

93/4 of Citric .Acid, or fl. drs. iiss. of Lemon-juice.

,,

Bicarb. of Soda

=

,,

,, fl. OZ. ss.

,,

,,

Carb. of Potash

=

,,

,, fl. OZ. ss.

,,

,,

Sesq. of Ammonia

=

,,

fl. drs. vj.

,,

Incompatibles. Alkalies and their Carbonates, Sulphates, and Tartrates; Carbonates of Earths and Metals; Acetates.

883. Therapeutic Uses

In Fevers, it proves a useful and grateful refrigerant. In some irritable states of the stomach it affords, in many instances, a great amount of relief; and in Scurvy, it has been used with great advantage, although inferior to Lemon-juice. (See Citrus Limonum.)