524 MEDICAL JURISPRUDENCE
kept long and exposed to light, a portion of the mercury is converted into
mercuric oxide which produces a poisonous action on the system.
2. Pilula hydrargyri (Blue pill).—It contains 33 per cent of mercury.
The dose is 4 to 8 grains.
3. Unguentum hydrargyri (Blue ointment).—It contains 30 per cent of
4. Unguentum hydrargyri dilutum,—It contains 10 per cent of mercury.
5. Unguentum hydrargyri composition.—It contains 12 per cent of
6. Unguentum hydrargyri nitratis forte.—It contains 6.7 per cent of
7. Unguentum hydrargyri nitratis dilutum.—It contains not less than
the equivalent of 1.34 per cent of mercury.
COMPOUNDS OF MERCURY
1. Mercuric Oxide, HgO.—This is known in the vernacular as Sipichand.
It is a brick-red crystalline powder but it forms an amorphous yellow powder
when a mercuric salt is acted upon by caustic soda or potash. Both the red
and yellow varieties ,are insoluble in water. The red variety is a B.P.C. pre-
paration, and is known as Hydrargyri oxidum rubrura (red precipitate), the
dose being 1/16 to i grain. It is used for preparing a B.P.C. ointment,
Unguentum Hydrargyri oxidi rubri (red ointment). The yellow variety
is a pharmacopoeial preparation, and is known as Hydrargyri oxidum flavum.
It is contained in the official preparations of Oculentum hydrargyri oxidi
and Oculentum atropinos cum hydrargyri oxido and enters into the com-
position of Hydrargyri oleatum (mercuric oleate) and Unguentum hydrar-
2. Mercuric Chloride (Perchloride of Mercury, Corrosive Sublimate),
HgCL.—It exists in the form of heavy, colourless masses of prismatic crystals
or as a white, crystalline powder. It has a styptic, nauseous, metallic taste.
It is soluble in eighteen parts of cold water and three parts of boiling water.
It is readily soluble in alcohol (90 per cent), ether and glycerin and is very
soluble in solutions of the alkaline chlorides. On account of its antiseptic
properties it is largely used in medicine as well as in taxidermy. It is a
violent poison, and is obtained in the bazaar, often mixed with impure
subchloride. The official dose of mercuric chloride (Hydrargyri per-
chloridum) is 1/32 to 1/16 grain. The pharmacopoeial solution, Liquor
hydrargyri perchloridi, contains 0.1 per cent of mercuric chloride, the dose
being 30 to 60 minims.
When ammonia is added to a watery solution of mercuric chloride,
ammonio-chloride of mercury is formed. It is also known as ammoniated
mercury or white precipitate (Hydrargyrum ammoniatum, B.P.). It is a
white, heavy, tasteless powder, insoluble in water, alcohol (90 per cent) and
ether, but readily soluble in warm hydrochloric acid and in warm acetic
acid. It is used in preparing an official ointment, Unguentum hydrargyri
ammoniati (whi£e precipitate ointment) t,
3. Mercuric Iodide, HgI2.—This is also called red iodide of mercury
or biniodide of mercury. It is a scarlet red powder, obtained by the action
of a watery solution of mercuric chloride on one of potassium iodide. It is
almost ^ insoluble in water, but soluble in about 130 parts of alcohol, and
freely in ether, in nitric acid and in a solution of potassium iodide or mer-
curic chloride. It forms one of the constituents of a non-official preparation,
Liquor arseni et hydrargyri iodidi (Donovan's solution), the dose of which
is 5 to 15 minims.