Tartar, Salt of. Carbonate of potassa.
Tartar, Sol′uble. Neutral tartrate of potassa.
Tartar, Spirit of. Pyrotartaric acid.
TARTAR′IC ACID. H2C4H4O6. Syn. Acid of tartar, Essential salt of t.†; Acidum tartaricum (B. P., Ph. L., E., & D.), Sal essentiale tartari†, L. Prep. 1. (Ph. L. 1836.) Take of cream of tartar, 4 lbs.; boiling water, 2 gall.; dissolve by boiling; add, gradually, of prepared chalk, 12 oz. 7 dr. (made into a milk with water), and, when the effervescence ceases, add another like portion of prepared chalk, dissolved in hydrochloric acid, 261⁄2 fl. oz., or q. s., diluted with water, 4 pints; collect the precipitate (‘tartrate of lime’), and, after well washing it with water, boil it for 15 minutes in dilute sulphuric acid, 7 pints and 17 fl. oz.; next filter, evaporate the filtrate (to the density of 1·38), and set it aside to crystallise; redissolve the crystals in water, concentrate the solution by evaporation, and recrystallise a second and a third time. The Edinburgh formula is nearly similar. In the Ph. L. & D. tartaric acid is placed in the Materia Medica.
2. (Gatty.) The solution of argol or tartar is first neutralised with carbonate of potassa, and to every 300 gall. of the clear liquid, at 5° Twaddell, 34 gall. of milk of lime (1 lb. of lime per gall.) are added; carbonic acid gas is then forced in, with agitation; decomposition ensues, with the formation of ‘bicarbonate of potassa’ and ‘tartrate of lime,’ the last is converted into tartaric acid in the usual manner, and the former is evaporated in iron pans, and roasted in a reverberatory furnace for its potassa.
Prop. Tartaric acid forms inodorous, scarcely transparent, oblique rhombic prisms, more or less modified, which are permanent in the air; it possesses a purely sour taste, dissolves in about 2 parts of water at 60° Fahr., and in about its own weight of boiling water; it is slightly soluble in alcohol; the aqueous solution exhibits right-handed polarisation, and suffers gradual decomposition by age.
It is free from colour; is entirely, or almost entirely, dissipated by ignition; and is entirely soluble in water.
Tests. 1. Tartaric acid is known to be such by its solution giving white precipitates with solutions of caustic lime, baryta, and strontia, which dissolve in excess of the acid.—2.
A solution of potassa causes a white granular precipitate of cream of tartar, soluble by agitation in excess of the precipitant.—3. Nitrate of silver and acetate of lead give white precipitates, which, when heated, f nine, and yield the pure metal.—4. If to a solution of tartaric acid, or a tartrate, solution of a ferric or aluminum salt be added, and subsequently ammonia or potassa, no precipitate is formed.—5. At about 570° Fahr. all the tartrates are blackened, and yield a peculiar and characteristic odour.
Uses, &c. Tartaric acid is chiefly employed in calico printing, and, in medicine, as a substitute for citric acid and lemon juice in the preparation of cooling drinks and saline draughts. For the latter purpose, bicarbonate of soda is the alkaline salt commonly employed.—Dose, 10 to 30 grains.