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Experiment 2. If the white oxyd or arsenious acid be dissolved in muriatic acid, the same compound will result, which, on evaporation, will form small crystalline grains.

SULPHATE OF ARSENIC.

Experiment 1. When arsenic is digested in sulphuric acid, a compound will be formed called sulphate of arsenic, which is a white powder very imperfectly soluble in water.

ACETATE OF ARSENIC.

Experiment 1. When arsenious acid or white oxyd of arsenic, is digested in acetic acid, it will be dissolved and form acetate of arsenic, which will deposit regular crystals. See Arsenic.

Remark. The following are the general properties of the salts of arsenic.

1. Prussiate of potash occasions a white precipitate;

2. Hydro-sulphuret of potash forms a yellow precipitate; and,

3. Infusion of nut-galls produces no change.

SECTION XIX.

SALTS OF COBALT.

NITRATE OF COBALT.

Experiments 1. When cobalt is dissolved in nitric acid, and the solution evaporated, red prismatic crystals of nitrate of cobalt will be the result.

Experiment 2. If one part of cobalt be dissolved in three of diluted nitric acid, and diluted with 24 of water,

and one part of muriate of ammonia added, Hellot's sympathetic ink will be prepared.

Remark. Letters traced by this solution are invisible while cold, but when very moderately heated they become green, if the cobalt contains much iron, but blue, if free from iron.

MURIATE OF COBALT.

Experiment 1. When oxyd of cobalt is dissolved in muriatic acid, muriate of cobalt will be found; or,

Experiment 2. If nitro-muriatic acid be used, the same salt will be produced.

Remark. The solution of cobalt in muriatic acid is blue, if it be neutral; if there be an excess of acid, the solution is green. See Cobalt.

Experiment 2. If characters be written with this so. lution, they will be invisible; but if heat be applied they will become green, forming a sympathetic ink. See Cobalt.

SULPHATE OF COBALT.

Experiment 1. If oxyd of cobalt be dissolved in sulphuric acid, and the solution evaporated, crystals of sulphate of cobalt will be obtained, which will form in rhomboidal prisms, terminated by dihedral summits.

Remark. This salt contains 26 acid, 30 oxyd, and 34 water. It readily combines with potash and ammonia, and forms triple salts with each.

ACETATE OF COBALT.

Experiment 1. If one part of oxyd of cobalt be dissolved in 16 parts of distilled vinegar, and the solution evaporated to one fourth, and one fourth, of the cobalt, of muriate of soda be then added, the blue sympathetic ink of Ilseman will be formed.

Remark. The remaining salts of cobalt are not much known.

The salts of this metal exhibit the following properties:

1. Alkalies precipitate a blue powder.

2. Hydro-sulphuret of potash affords a black preci. pitate; and,

3. Infusions of nut-galls produces a yellowish white precipitate.

SECTION XX.

SALTS OF MANGANESE.

NITRATE OF MANGANESE.

Experiment 1. If to a mixture of the black oxyd of manganese and nitric acid, a little sugar be added, and heat applied, the oxyd will be dissolved, and form nitrate of manganese. See Manganese.

MURIATE OF MANGANESE. Experiment 1. When muriatic acid is digested on black oxyd of manganese, an abundance of oxy-muriatic acid is disengaged, and muriate of manganese is formed, which crystallizes on evaporation.

Experiment 2. If red oxyd of manganese be treated in the same manner, the result is oxy-muriate of manganese,

SULPHATE OF MANGANESE. Experiment 1. If the white or red oxyd of manganese be dissolved in sulphuric acid, the result is sulphate of manganese.

Experiment 2. If the black oxyd be used in the same manner, oxygen gas will be liberated, and sulphate of manganese formed.

Remark. There are two combinations of sulphuric acid and the oxyd of manganese; one with the white, and another with the red oxyd. The sulphate crys. tallizes and the oxy-sulphate gelatinizes. The other compounds of this metal with acids, are but little known.

The salts of manganese, are characterised by the following properties :

1. Alkalies throw down from them, a red or white precipitate, which become black when exposed to the

air;

2. Prussiate of potash occasions a yellowish white precipitate;

3. Hydro-sulphuret of potash forms a white precipitate; and,

Gallic acid produces no change.

SECTION XXI.

SALTS OF CHROMIUM.

The salts of this metal are but very little known. They possess, as far as facts are able to determine, the following properties :

1. Prussiate of potash occasions a brown colour;

2. Infusion of nut-galls affords a brown precipitate; and,

3. Hydro-sulphuret of potash produces a green précipitate, which becomes yellow on the addition of nitric acid. The oxyd of chromium is soluble in the nitric, muriatic, phosphoric, sulphurous, and oxalic acids. See Chromium.

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SECTION XXII.

SALTS OF MOLYBDENUM.

NITRATE OF MOLYBDENUM.

Experiment 1. If molybdenum be digested in nitric acid by the assistance of heat, the nitrate of molybdenum will be formed.

Remark. If the quantity of metal be greater than the acid can dissolve, the solution is blue, but where a small quantity of molybdenum is dissolved in a considerable proportion of acid, the solution is yellowish brown.

MURIATE OF MOLYBDENUM.

Experiment 1. If the oxyd of molybdenum be dissolved in muriatic acid, the result will be muriate of molybdenum, which is of a blue colour.

SULPHATE OF MOLYBDENUM.

Experiment 1. If the oxyd of molybdenum be dissolved in sulphuric acid, a yellowish brown or a blue solution of sulphate of molybdenum will result.

Remark. The other salts of molybdenum are but little known. See Molybdenum.

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