Marsh's Dahlia Test

Make a strong infusion of the petals of dark dahlias; strain, and add to every pint 1/2 oz. of strong sulphuric acid; stir with a glass rod, and when cold, add to each pint 2 grs. of corrosive sublimate. Filter through coarse cloth, and bottle. When required for use, neutralize it carefully with ammonia, and use the liquid by dipping paper in it.

Solution of Carbonate of Ammonia

Mr. Parnell directs this test to be prepared by dissolving 1 part of sublimed carbonate of ammonia in 3 of water, and adding 1 part of water of ammonia.

Solution of Oxalate of Ammonia

Dissolve 1 oz. of crystallized oxalate of ammonia in a pint of water.

Solution of Sulphuretted Hydrogen

Pass sulphuretted hydrogen gas (see Gases, further hack) through cold distilled water, which has been recently boiled, till it will absorb no more. Keep it in small bottles securely closed.

Solution of Hydrosulpbhuret of Ammonia

Hydrosul-phide, Hydrosulphate of Ammonia. Pass sulphuretted hydrogen gas (see further back) through water of ammonia till the liquid occasions no precipitate in a solution of sulphate of magnesia.

Solution of Ammonio-nitrate of Silver

It gives a pale yellow precipitate with arsenious acid, and a chocolate red with arsenic acid; the same with their salts. See Pocket Formulary.

Solution of Nitrate of Silver

The Edinburgh Pharmacopoeia directed this test to be prepared by dissolving 40 grains of the nitrate in a fluid ounce of distilled water. The London Pharmacopoeia directed 60 grs. to a fluid ounce. Mr. Parnell recommends 1 part to 15 or 20 of water. [It is used chiefly for the detection of chlorine or hydrochloric acid. The precipitated chloride of silver is insoluble in nitric acid. Also for hydrocyanic acid, with which it gives a white precipitate, which is decomposed by heat, the silver being reduced.

Solution of Ammonio-sulphate of Copper

Chiefly used as a test for arsenical compounds, with which it gives a green precipitate. See Pocket Formulary.

Solution of Chloride of Barium

See Pocket Formulary.

Solution of Indigo

See Pocket Formulary.

For the Test Solutions of the B

P., see Pocket Formulary.

Hahnemann's Wine Test, for detecting lead in wine. Sulphuret of lime 3 oz., tartaric acid 3 oz., water 2 lbs., mix, decant, and add 1 oz. of tartaric acid. Or, simple sulphuretted hydrogen water 4 oz., tartaric acid 1 dr. For the detection of other adulterants in wine, see Cooley, article "Wine.",

Nitric Acid Test for albumen in urine

Fill a test-tube to the depth of about an inch with the urine, then incline the tube and pour in strong nitric acid, so that it may trickle down along the side of the tube to the bottom and form a stratum some quarter of an inch thick below the urine. If the urine contain albumen three layers will be perceptible - one, perfectly colourless, of nitric acid at the bottom; immediately above this an opalescent zone of the coagulated albumen, and on the top the unaltered urine.

Heat Test, for albumen in urine

- "If the urine have its usual acid reaction it becomes turbid on boiling when it contains albumen, and this turbidity persists after the addition of an acid. There are two points to be remembered on using heat alone as a test for albumen: - First, that albumen is not coagulated by heat when the urine is alkaline; in such cases, therefore, it is necessary before boiling; to restore the acidity by a few drops of acetic acid. Secondly, when the urine is neutral, or very feebly acid, it may become turbid on heating, from precipitation of the earthy phosphates; but turbidity from this cause is easily distinguished from albumen by a drop of acetic or nitric acid, which instantly causes the phosphates to disappear." - Dr. Roberts.