medy this defect he proposes using nitrate of mercury prepared without heat, or to add to the solution of muriate of soda a quantity of muriatic acid. It is contended, that if the solution of nitrate of mercury be poured into that of the muriate of soda, no sub-nitrate is formed.

Calomel is a dull white mass, which becomes yellowish when reduced to powder. When slowly sublimed, it crystallizes in four sided prisms terminated by pyramids. Its specific gravity is 7.1758. It is insoluble in water. It is tasteless. When rubbed in the dark it phosphoresces. It requires a higher temperature to sublime it than oxymuriate of mercury. Oxymuriatic acid, and nitric acid converts it into oxymuriate. It is composed of about eleven acid and eighty-nine prot-oxyd of mercury.

MURIATE OF MERCURY AND AMMONIA.

Experiment 1. If equal weights of muriated quicksilver, and sal ammoniac be mixed in solution, a triple salt is formed called muriate of mercury and ammonia, or sal alembroth of the alchymists.

Rationale. When to a solution of muriate of ammonia there is added muriate of mercury, about thirty times more of the latter is dissolved than the same quantity of pure water is capable of dissolving, and a change of temperature ensues; consequently a combination takes place, and a triple muriate is produced.

Experiment 2. If to the mixed solution of Experiment 1, there be added another of carbonate of potash, a precipitate of sub-muriate of mercury and ammonia, or white precipitate of the shops will be formed.

Rationale. When to a solution of sal alembroth or muriate of mercury and ammonia, carbonate of potash is added, there occurs a partial decomposition; for the alkali combines with a portion of the muriatic acid, and reduces the muriate of mercury and ammonia to the state of a sub-muriate, which being insoluble, falls to the bottom of the solution.

Remark. This combination consists of 31 oxyd of mercury, 16 muriatic acid, and three ammonia.

SULPHATE OF MERCURY.

Experiment 1. If sulphuric acid diluted with its own weight of water be boiled over mercury, and the solution evaporated, sulphate of mercury will be obtained in small prismatic crystals.

Rationale. The sulphuric acid in part is decomposed; its oxygen oxydizes the mercury, whilst the undecomposed acid combines with the mercury into a sulphate of mercury readily soluble in water.

Experiment 2. If to the solution of sulphate of mercury potash be added, a dark coloured precipitate of sub-sulphate will be obtained.

Rationale. The alkali unites with the greater part of the acid, forming sulphate of potash, and oxyd of mercury is precipitated in combination with a portion of acid in the state of sub-sulphate.

Remark. This salt contains 12 acid, 83 prot oxyd of mercury, and 5 water.

Experiment 3. When three parts of sulphuric acid are boiled on two parts of mercury, the whole, by continuing the heat, is converted into oxysulphate of mercury, which crystallizes in small prisms.

Experiment 4. If sulphuric acid in excess be present in the salt, the super-oxysulphate of mercury is formed, which deliquesces in the air.

Experiment 5. If water be poured upon the oxysulphate, it is converted into super-oxysulphate, which dissolves, and sub-oxysulphate, which remains in the state of a beautiful yellow powder, called turpeth mineral, which contains 15 acid, and 85 per oxyd.

PHOSPHATE OF MERCURY.

Experiment 1. If the solutions of phosphate of soda and nitrate of mercury be mixed, a white precipitate will be obtained, of phosphate of mercury, containing 28.5 acid, and 71.5 per oxyd.

Rationale. The phosphoric acid unites with the mercury, and the nitric acid combines with the soda.

ACETATE OF MERCURY.

Experiment 1. If acetate of potash be added to nitrate of mercury, acetate of mercury will be produced, which crystallizes in plates of a silvery whiteness.

Rationale. The nitric acid passes to the potash, and the acetic acid to the mercury.

Experiment 2. If red oxyd of mercury be dissolved in acetic acid, a yellow uncrystallizable mass will be obtained, which deliquesces in the air, called oxacetate of mercury.

PRUSSIATE OF MERCURY,

Experiment 1. If red oxyd of mercury and prussian blue be mixed, and boiled in water, prussiate of mercury will result, which crystallizes in four sided prisms, terminated by four sided pyramids.

OXALATE OF MERCURY.

Experiment 1. If a solution of super-oxalate of potash be digested on red oxyd of mercury, the super-oxalate of mercury will be formed.

Rationale. The excess of acid unites with the mercury, by which the oxyd is changed from a red colour, and oxalate of mercury is formed. Or,

Experiment 2. If nitrate of mercury be added to oxalate of potash, oxalate of mercury will be precipitated.

Rationale. The nitric acid unites with the potash, and the oxalic acid with the oxyd of mercury.

Remark. This compound when treated detonates. It constitutes the greater part of Howard's fulminating mercury. See an Essay of the author, on the fulmina ting compounds of mercury, in Coxe's Medical MuSee also Mercury. B b

seum.

The remaining salts of this metal are hardly known, viz. the carbonate, fluate, borate, succinate, benzoate, mellate, tartrate, citrate, arseniate, molybdate and chromate of mercury.

The salts of mercury are characterized by the following properties:

1. They are volatilized, when strongly heated.

2. The prussiates occasion a white precipitate.

3. Hydrosulphuret of potash produces a black precipitate; and,

4. Tincture of galls occasions an orange yellow precipitate.

SECTION V.

SALTS OF PALLADIUM.

The salts of this metal are rare: they are soluble in water, and are known by the following characters : 1. Prussiate of potash occasions a dirty brown precipitate; and,

2. Hydrosulphuret of potash and the alkalies an orange yellow precipitate. See Palladium.

SECTION VI.

SALTS OF RHODIUM.

The salts of this metal, like the preceding, are not yet sufficiently known to admit of a particular description. The solution of these salts, however, are red. They are not precipitated by prussiate of potash, hydrosulphuret of potash, sal animoniac and alkaline salts; but the pure alkalies throw down a yellow powder, soluble in an excess of alkali.

SECTION VII.

SALTS OF IRIDIUM.

The solution of these salts is at first green; but acquires a red colour when concentrated in an open vessel. Prussiate of potash and tincture of galls produce no precipitate, but they render the solutions of this metal colourless.

SECTION VIII.

SALTS OF OSMIUM..

Among the very rare salts we may include those of this metal; although this genera of salts is still unknown, yet there is no doubt but certain combinations may be effected with this metal as with others.

SECTION IX.

SALTS OF COPPER.

NITRATE OF COPPER.

Experiment. If copper be dissolved in nitric acid, and the solution evaporated, crystals of nitrate of copper will form in regular parallelopipedes.

Experiment 2. If this salt be exposed to heat, it will liquefy or undergo the watery fusion; and,

Experiment 3. If the heat be continued it is gradually decomposed, the acid. is driven off, and the black oxyd of copper remains in a state of purity.