Therapeutics. - Externally and Locally. - As a germicide, antiseptic, and antiparasitic the preparations of mercury are extremely valuable; the corrosive chloride of mercury being extensively employed as an antiseptic in general surgery in strengths of from 1: 1000 to 1: 10,000. It attacks the fingers and instruments, and is not always a reliable germicide.

In diseases of the skin due to animal or vegetable parasites there are no drugs so valuable as certain preparations of mercury, the ointment of ammoniated mercury being highly prized.

Calomel in the form of an ointment, 5 to 20 grains (0.3-1.25 Gm.) to 1 ounce (32.0 Gm.) is an efficient remedy in eczema.

Indolent venereal ulcers are much improved by dusting them with calomel, while the early inflammatory conditions of these sores may be greatly benefited by the use of black wash.

Many diseases of the eye, ear, nose, and throat yield to various preparations of mercury. The ointment of the yellow oxide of mercury is particularly adapted to phlyctenular ophthalmia, pannus, keratitis, chronic blepharitis marginalis, etc.

Inunction with mercurial ointment or with oleate of mercury is excellent for the constitutional treatment of the first and second stages of syphilis. These two preparations are of great value in subacute synovitis, pelvic cellulitis, and syphilitic orchitis and epididymitis.

The ointment of the red iodide of mercury has a reputation as an efficient remedy in goiter and syphilitic enlargement of the spleen, as well as in pachymeningitis.

The solution of nitrate of mercury is an active and reliable caustic in the treatment of phagedenic ulcerations and venereal ulcerations of the os uteri.

The use of mercurials is usually attended with excellent results in promoting resolution of fibrous induration resulting from chronic inflammation.

Internally. - The principal use of mercury is undoubtedly as an antisyphilitic. Mercury is an antidote against constitutional syphilis, being particularly efficient in the secondary stage. Many methods of mercurializing a patient have been adopted, mention of which will be made under "Administration." It is perhaps unnecessary to caution the therapeutist to make an accurate and positive diagnosis of syphilis before instituting the mercurial treatment, as otherwise the consequences may be disastrous.

Mercury has been used in all stages of the disease, though, possibly from ignorance of its proper use, its employment has met with less favorable results in the primary than in the secondary form, while a careful study of syphilology leads one to believe that in tertiary syphilis it is inferior to the iodides. Many patients, however, do better under mercury than they do under the iodides.

The medical uses of mercurial preparations in disorders of the alimentary tract are very numerous.

Chronic dysentery will frequently yield to 1/100 to 1/60 grain (0.0006-0.001 Gm.) of corrosive chloride of mercury, and diarrheas of children - particularly those characterized by pale, offensive stools - together with ileo-colitis of infants, are greatly benefited by small doses of calomel or gray powder.

As a purgative in bilious attacks, hepatic congestion, and cirrhosis calomel is an extremely valuable drug. Its action as a purgative will be more fully described under "Cathartics." Calomel is also a remarkably efficient diuretic, especially when combined with digitalis.

Many acute febrile and inflammatory conditions, such as meningitis, pericarditis, and hepatitis, are sometimes benefited by the internal administration of calomel, though in acute inflammations the chief value of the drug, whether specific or non-specific, is manifest in iritis and in acute bronchitis which shows a tendency to persist.

Calomel given early in from 10- to 20-grain (0.6-1.3 Gm.) doses in cases of pneumonia is esteemed very highly by some authorities.

Calomel and opium have been used and recommended by some physicians in the treatment of Asiatic cholera. In chlorosis and marasmus of infants very small doses of corrosive mercuric chloride, 1/120 to 1/100 grain (0.0005-0.0006 Gm.) have proved very beneficial in many cases.

Contraindications. - Mercury is usually contraindicated in tuberculosis and in persons of strumous diathesis; and while it is of value when judiciously employed in chronic interstitial nephritis, it must nevertheless be given cautiously, and if the excretion of urine is diminished by its use, the drug should be immediately discontinued.

Children, though not easily salivated, are very susceptible to other poisonous actions of calomel.

Ordinarily, acute asthenic diarrhea and dysentery in adults would contraindicate the use of mercurials.

Administration. - Mercury is introduced into the system by -

1. Inunction. - The portion of the body upon which the preparation is to be applied should first be thoroughly washed with soap and warm water, and the ointment well rubbed in with the palm of the hand. The best localities for application are the inner sides of the thighs, the sides of the chest, the axillae, abdomen, and back. An excellent way to mercurialize a child is to put the ointment on the abdomen, beneath a flannel binder. An efficient means also of favoring absorption is to apply the ointment to the soles of the feet, when it will be rubbed in by walking. Mercurial ointment is ordinarily used for this purpose, 15 to 30 grains (1.0-2.0 Gm.) being required for each inunction. Gleate of mercury when applied externally should not be rubbed in, the simple application to the skin being sufficient.

2. Fumigation. - The iodide, mercuric sulphide, and calomel are used in this manner. The latter preparation, being preferable, is the one ordinarily used. From 5 to 20 grains (0.3-1.3 Gm.) of calomel are put in a plate or a porcelain dish over a lighted spirit-lamp. These are placed under a cane-bottomed chair, in which the patient sits, nude, enveloped in a blanket reaching to the floor and fastened loosely about the neck. The calomel is volatilized by the heat, deposited in minute particles over the surface of the body, and readily absorbed. The fumigation should last fifteen to twenty minutes.

3. Endermically. - Mercurials may be absorbed by dusting calomel and certain other preparations on ulcers, open wounds, etc.

4. By the Rectum. - Mercury may be administered in the form of a suppository containing 5 to 10 grains (0.3-0.6 Gm.) of mercurial ointment.

5. Hypodermically. - From 1/12 to 1/6 grain (0.005-0.01 Gm.) of the bichloride of mercury, dissolved in 5 to 10 minims (0.3-0.6 Cc.) of distilled water, is injected deeply into the muscles of the gluteal region or in the subcutaneous areolar tissue of the back. The solution of peptonate of mercury has been used for this purpose, though the preparation which is the least objectionable is the solution of the formamidate of mercury, 16 minims (1.0 Cc), corresponding to 1/6 grain (0.1 Gm.) of mercuric chloride.

Numerous preparations have been recommended for hypodermic use. Many of them are of service, but space does not permit of their individual consideration. Cypridol is an excellent preparation.

6. Internally. - In the treatment of syphilis nearly every preparation of mercury has been employed, authorities differing in their choice. Bumstead prefers the bichloride, the mercurous iodide, and the mercurial pill; Berkeley Hill, the red mercuric iodide; Fox, the cyanide; Hutchinson, the gray powder, etc. It matters little which of these preparations is used. That which agrees best with the patient is advisable. Calomel, gray powder, blue pill, and corrosive sublimate are ordinarily used in disorders of the alimentary tract. As a rule, the first two are preferable.