Citric acid

 Citric Acid

Citric Acid is used to check profuse sweating, and as a substitute for lemon juice when it cannot be procured.

Dose , from ten to thirty grains. 

Adulteration of Lemon Acid [i.e. Citric Acid]

It is well known to every one, that the expressed juice of lemons is extremely apt to spoil, on account of the sugar, mucilage, and extractive matter which it contains; and hence various means have been practised, with the intention of rendering it less perishable, and less bulky. The juice has been evaporated to the consistence of rob; but this always gives an unpleasant empyreumatic taste, and does not separate the foreign matters, so that it is still apt to spoil when agitated on board of ship in tropical climates. It has been exposed to frost, and part of the water removed under the form of ice; but this is liable to all the former objections; and, besides, where lemons are produced in sufficient quantity, there is not a sufficient degree of cold. The addition of a portion of spirit to the inspissated juice, separates the mucilage, but not the extractive matter and the sugar. By means, however, of separating the foreign matters associated with it, in the juice, by chemical processes unnecessary to be detailed here, citric acid is now manufactured, perfectly pure, and in a crystallised form, and is sold under the name of concrete lemon acid. In this state it is extremely convenient, both for domestic and medicinal purposes. One drachm, when dissolved in one ounce of water, is equal in strength to a like bulk of fresh lemon juice. To communicate the lemon flavour, it is only necessary to rub a lump of sugar on the rind of a lemon to become impregnated with a portion of the essential oil of the fruit, and to add the sugar to the lemonade, negus, punch, shrub, jellies or culinary sauces, prepared with the pure citric acid.

Fraudulent dealers often substitute the cheaper tartareous acid, for citric acid. The negus and lemonade made by the pastry-cooks, and the liquor called punch, sold at taverns in this metropolis, is usually made with tartareous acid.

To discriminate citric acid from tartareous acid, it is only necessary to add a concentrated solution of the suspected acid, to a concentrated solution of muriate of potash, taking care that the solution of the acid is in excess. If a precipitate ensues, the fraud is obvious, because citric acid does not produce a precipitate with a solution of muriate or potash.

Or, by adding to a saturated solution of tartrate of potash, a saturated solution of the suspected acid, in excess, which produces with it an almost insoluble precipitate in minute granular  crystals. Pure citric acid produces no such effect when added in excess to tartrate of potash.