Characters. - A metal, fluid at common temperatures, brilliantly lustrous, and easily divisible into spherical globules. Reaction. - Volatilises at a heat below that of visible redness, leaving no residue.

Preparations Containing Mercury

I. In the metallic state.

B.P. (9)

u.s.p. (7)

Hydrargyrum.

Hydrargyrum.

Emplastrum Ammoniaci cum Hy-drargyro (1 in 5).

Emplastrum Ammoniaci cum Hy-drargyro.

Emplastrum Hydrargyri (1 in 3).

Emplastrum Hydrargyri.

Hydrargyrum cum Creta (1 in 3).

Hydrargyrum cum Creta.

Linimentum Hydrargyri (v. p. 516) (1 in 6)

Pilula Hydrargyri (v. p. 522) (1 in 3).

Massa Hydrargyri.

Suppositoria Hydrargyri (1 in 6).

Unguentum „ (1 in 2).

Unguentum Hydrargyri.

„ ,, Compositum (1 in 4 1/2).

„ „ Compositum.

(5) II. Oxidised. (4)

Hydrargyri Oxidum Flavum.

Hydrargyri Oxidum Flavum.

„ „ Rubrum.

„ „ Rubrum.

Lotio Hydrargyri Flava.

,, ,, Nigra.

Unguentum Hydrargyri Oxidi Flavi

Unguentum Hydrargyri Oxidi Rubri.

,, „ ,, Rubri

III. Sulphuretted. (1)

None.

Hydrargyri Sulphidum Rubrum.

IV. As Mercurous Chloride.

(3)

(3)

Hydrargyri Subcbloridi.

Hydrargyrum Chloridum Mite.

Pilula Hydrargyri Subcbloridi Com-posita (vide p. 522).

Pilulae Antimonii Compositae (vide p. 523).

Unguentum Hydrargyri Subcbloridi.

Pilulae Catharticae Compositae (vide p. 523).

1 Altered from the United States Dispensatory, p. 773.

Preparations containing Mercury - continued.

V. As Mercuric Chloride.

B.P. (4)

Hydrargryri Perchloridum. Hydrargyrum Aramoniatum. liquor Hydrarg-yri Perchloridi. Unguentum Hydrargyri Ammoniatum.

u.s.p. (3)

Hydrargyri Chloridum Corrosivum. Hydrargyrum Ammoniatum.

Unguentum Hydrargyri Ammoniati.

VI. Combined with Iodine.

(3) Hydrarg-yri Iodidum Rubrum,

Liquor Arsenii et Hydrargryri Iodidi. Unguentum Hydrargryri Iodidi Rubri.

(3) Hydrargyri Iodidum rubrum.

„ „ Viride.

Liquor Arsenii et Hydrargyri Iodidi*

VII. Combined with Cyanogen.

None.

(1) Hydrargyri Cyanidum.

VIII. Oxidised and combined with Acids.

(5) Hydrarg-yri Persulphas.

Liquor Hydrarg-yri Nitratis Acidus. Oleatum Hydrargryri. unguentum Hydrargryri Nitratis.

" " " Dilutum.(4)

Hydrargyri Sulphas Flava. Liquor Hydrargyri Nitratis. Oleatum Hydrargyri. Unguentum Hydrargyri Nitratis.

Impurities. - Other metals.

Tests. - The presence of other metals is ascertained by their being left behind as a residue when the mercury is volatilised. It is indicated by the formation of a grey scum or dust on the surface of the metal after exposure to air, and by the mercury forming globules which are not sjpherical but elongate to a tail when allowed to run over a piece of paper. They are also recognised by shaking the mercury in a perfectly dry bottle, when a grey powder will be formed if they are present.

On boiling 5 grms. of distilled water with 5 grms. of mercury and 4.5 grms. of hyposulphite of sodium in a test-tube for a minute, the mercury should not lose its lustre nor acquire more than a slightly yellowish shade (absence of more than a trace of other metals, U.S.P.).

Purification. - Other metals may be separated by distillation, or by mixing the mercury with strong sulphuric acid and letting it stand in the cold for twenty-four hours. The other metals will be converted into sulphates, but mercury is only attacked by sulphuric acid when it is aided by heat. The mercury is then washed with water to remove the sulphates, and dried with blotting-paper. Mercury is freed from dust and mechanical impurities by pressing it through chamois leather or filtering it through a paper filter in the apex of which several small holes have been made with a needle or pin.

Uses. - Metallic mercury in mass has no action whatever on the body. As much as a pound has been taken without producing any physiological effect. Such a dose as this is sometimes given in cases of intestinal obstruction in the hope that the weight of the mercury may carry the obstruction before it. The theory of its action formerly held was purely mechanical: that the mercury passed from the stomach to the intestines and meeting with the obstruction drove it on; but latterly Traube has supposed that the mercury remains chiefly in the stomach, and by pulling on it excites the intestines reflexly to peristaltic action. Whatever the correct theory may be, however, it is certain that the mercury does not always stay in the stomach, but does get down into the intestine, and consequently some precautions must be observed in its administration, and it is never given except when all other measures fail. The precautions are not to give it in cases of intussusception, as it may very probably render this worse; nor in cases where the intestine is considerably inflamed, as the tissues being weak are then easily .torn; nor in hernia, as better means, viz. external means, can be employed.