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Dilute Phosphoric Acid

Mix a substitute for citric acid and lemon juice, 5 troy ounces nitric acid with 1/2 pint distilled for the preparation of cooling drinks and saline troy ounces nitric acid with pint distilled for the preparation of cooling drinks and saline water in a porcelain capsule of the capacity draughts. of 2 pints; add 6 drachms phosphorus and 3930. Το Obtain Tartaric Acid. On invert over it a glass funnel of such dimen- the small scale it is prepared as follows: Dissions that its rim may rest on the inside of solve 4 pounds cream of tartar in 2 gallons the capsule, near the surface of the liquid. boiling water; add gradually 12 ounces 7 Place the capsule on a sand-bath, and apply drachms chalk; and, when the effervescence a moderate heat until the phosphorus is dissolved, and red vapors cease to rise. If the reaction becomes too violent, add a little distilled water; and if the red vapors cease to be evolved before the phosphorus is all dissolved, gradually add nitric acid (diluted as before) until the solution is effected. Remove the funnel, continue the heat until the excess of nitric acid is driven off, and a syrupy liquid, free from odor and weighing 2 troy ounces, remains. Mix this, when cold, with sufficient distilled water to measure 20 fluid ounces, and filter through paper.

Or: Dissolve 1 troy ounce glacial phosphoric acid in 3 fluid ounces distilled water; add 40 grains nitric acid, boil to a syrupy liquid, free from the odor of nitric acid, add distilled water to make up to 124 fluid ounces, and filter. 3925. Tests for the Purity of Phosceases, add another like portion of chalk, dissolved in 26½ fluid ounces muriatic acid, diluted with 4 pints water; collect the precipitated tartrate of lime, and well wash it with water, then boil it for 15 minutes in 8 pints 1 fluid ounce dilute sulphuric acid; next filter, evaporate to the density 1.38, and set it aside to crystallize. The crystals must be dissolved and crystallized a second and a third time.

On the large scale, the decomposition of the tartar is usually effected in a copper boiler, and that of the tartrate of lime in a leaden cistern. This part of the process is often performed by mere digestion for a few days, without the application of heat. Leaden or stoneware vessels are used as crystallizers. Good cream of tartar requires 26 per cont. of chalk, and 28.5 per cent. of dry chloride of calcium for its perfect decomposition. Dry tartrate of lime requires 75 per cent. of oil of vitriol to phoric Acid. The U. S. Pharmacopeia liberate the whole of the tartaric acid. A directs that an aqueous solution of the acid very slight excess of sulphuric acid may be should yield no precipitate with sulphuretted advantageously employed. Some manufachydrogen , showing the absence of metals; it turers bleach the colored solution of the first should cause a white precipitate with chloride crystals by treating it with animal charcoal; of barium, soluble in excess of acid; and, but for this purpose the latter substance with an excess of ammonia, should cause only should be first purified by digesting it in mua slight turbidness, proving the almost total riatic acid, and afterwards by edulcorating it absence of earthy salts. If the presence with water, and exposing it to a dull red heat of arsenic is denoted by the tests for that in a covered vessel. The general managemetal, it may be separated by boiling with muriatic acid, so as to convert the arsenic into a volatile chloride, which would escape with vapors of the muriatic acid. 3926. Test for the Presence of Phosphoric Acid. Hydrochloric acid is added to the solution to acid reaction, and afterwards 1 or 2 drops of a concentrated solution of sesquichloride of iron; a solution of acetate of potassa is next added in excess, when a flocment of this manufacture resembles that of citric acid. (Cooley.)

3931. Το Detect Tartaric Acid in Citric Acid. Citric acid is sometimes adulterated with tartaric acid. This is readily detected by adding a solution of carbonate of potassa to a solution of the suspected acid; if tartaric acid be present, a crystalline precipitate of bitartate of potassa (cream of tartar) will be found. A more delicate test is to diculent white precipitate (sesqui-phosphate of gest the suspected acid with hydrated sesquiiron) will be found if phosphoric acid was oxide of iron in a test tube, and afterwards to present in any form or combination in the raise the heat slowly to the boiling point; alcriginal liquor. Arsenious acid, if present, lowing the excess of oxide to subside, decant should be removed by sulphuretted hydrogen before applying the test. (Cooley.)