A crystalline acid prepared from lemon-juice, or from the juice of the fruit of the lime, Citrus Bergamia.

Characters. - In colourless crystals, of which the right rhombic prism is the primary form; very soluble in water, less soluble in rectified spirit, and insoluble in pure ether. The crystals dissolve in three-fourths of their weight of cold, and in half their weight of boiling water. The diluted aqueous solution has an agreeable acid taste. When the solution is made by dissolving thirty-four grains of the acid in one ounce of water, it resembles lemon-juice in strength and in the nature of its acid properties, and, like lemon-juice, it undergoes decomposition and becomes mouldy by keeping.

The quantity contained in 1/2 fl. oz. of this solution, viz.:17 grains neutralises

25 grains bicarbonate of potassium. 20 ,, ,, sodium.

15 ,, carbonate of ammonium.

Preparation. - Vide p. 566.

Impurities. - Lead and copper from the vessels in which it is prepared, calcium used in its preparation, tartaric acid, which is cheaper, and is apt to be mixed with or substituted for it, sulphuric acid or sulphates, oxalic acid.

Tests. - The aqueous solution is not darkened by sulphuretted hydrogen (absence of metals), gives no precipitate when added in excess to solution of acetate of potassium (no tartaric acid), or of chloride of barium (no sulphates), and if sparingly added to cold lime-water it does not render it turbid (no oxalic acid). The crystals leave no ash when burned with free access of air (no calcium).

Dose. - 10 to 30 grains.

Preparations containing Free Citric Acid.


Succus Limonis. Syrupus Limonis. Vinum Quininae.


Syrupus Acidi Citrici. „ Limonis.