vomiting and purging, and even death, often preceded by dilated pupils, delirium, convulsions, and collapse. On post-mortem examination severe inflammation of the alimentary canal, kidneys, and bladder is found. The treatment consists in removing the application, or evacuating the contents of the stomach; the free use of diluents; opium (especially by the rectum); and avoiding all oily substances, as these aid the absorption of the poison.

What are its medicinal uses?

The internal uses of cantharides have previously been noticed (v. "Emmenagogues" and "Diuretics"). Externally it is used as a blistering agent, almost to the exclusion of other remedies. It inust be remembered that poisoning may result from its local application.

What are its preparations and their doses?

The cerate (ceratum cantharidis) is used locally as a blistering agent, and is often known as blistering cerate. Cantharidal collodion (collodium cantharidatum) is applied with a brush, and is a convenient way of applying a blister to an irregular surface. The tincture (tinctura cantharidis) is used internally; dose gtt. v-x (0.3-0.6).

CANTHARIS VITTATA-POTATO FLY.

What is this substance?

The potato fly (not official) is an indigenous insect which contains cantharidin, and may be used as a substitute for the Spanish fly.

AQUA AMMONIÆ FORTIOR-STRONGER WATER OF AMMONIA.

Is this ever used as a blistering agent?

Stronger ammonia-water is a rapid but painful vesicant.

It forms the basis of Granville's vesicating lotion and of Gondret's vesicating ointment. It is but little used for this purpose.

ORDER III.-SUPPURANTS.

What are suppurants?

Suppurants are remedies which cause such powerful irritation of the surface to which they are applied as to produce a crop of pus

tules. They are seldom employed at present except as an application to the throat and chest in chronic laryngeal or bronchial affections, or to the surface of a joint when chronic inflammation is present. The only medicines belonging to this order are Croton oil and antimonial ointment. These remedies have been previously described. Antimonial ointment is the more painful and its effects are more lasting. It is no longer official.

ORDER IV.-ESCHAROTICS.

What are escharotics?

Escharotics are medicines which are applied locally to destroy the structure and vitality of the tissues. The dead tissue excites inflammation, and is thrown off by ulcerative action. It is called the slough, or eschar. Escharotics are used to destroy morbid growths, as lupus, epithelium, condylomata, warts, fungous granulations, etc.; to destroy the virus of malignant pustule, hospital gangrene, the bites of rabid animals or poisonous reptiles, the virus of chancre, etc.; to substitute a healthy for diseased action, and to stimulate indolent ulcers, sinuses, etc.

Mention the principal medicines used for these purposes?

Caustic potash; caustic soda; arsenious acid; bromine; zinc chloride; acid nitrate of mercury; corrosive sublimate; potassium bichromate; the mineral acids; silver nitrate; copper sulphate; and burnt alum.

What is potassa?

POTASSA.

Potassa is formed by the rapid evaporation of the solution of potassa, and is moulded into thin cylindrical sticks.

What are its effects and uses?

It is an exceedingly powerful caustic, destroying the surrounding tissues and penetrating to some depth below the surface. When it is used, it is well to protect the surrounding tissues from its action by adhesive plaster with a hole cut in its centre, through which the caustic is applied. It is used when a powerful effect is desired.

Potassa cum Calce (potassa with lime) consists of equal parts of potassa and quicklime, and is a powerful caustic. It is sometimes called Vienna paste.

What is soda?

SODA.

Caustic soda is made by the rapid evaporation of the solution of soda, and is a very powerful caustic, resembling potassa in its effects London paste is made by rubbing up equal parts of soda

and uses.

and lime.

ACIDUM ARSENOSUM-ARSENOUS ACID.

Is arsenous acid used as a caustic?

The uses of this substance as a caustic will be found under the article "Arsenic" (v. "Alteratives").

What is bromine ?

BROMUM-BROMINE.

Bromine is a halogen element, and is a very powerful caustic. It is a volatile liquid, and has very great affinity for hydrogen. Locally it is a powerful deodorant and disinfectant, and a severe and deeply penetrating caustic. When inhaled, it is an intense irritant, producing laryngitis, bronchitis and even pneumonia. Internally, if not sufficiently diluted, it is a corrosive poison. It is used as a caustic in hospital gangrene after the removal of the slough. As it is heavier than water it may be poured into a wide-mouthed bottle half filled with water, which will prevent it from giving off irritating fumes. From this it may be sucked up with a syringe and injected into the wound which it is desired to cauterize. The fumes are sometimes cautiously inhaled for the cure of acute coryza, chronic nasal catarrh, ozana, hay asthma, etc. For purposes of inhalation a solution of 3ss (2.0) in 3jv (120.0) of alcohol may be used.

ZINCI CHLORIDUM-ZINC CHLORIDE.

LIQUOR HYDRARGYRI NITRATIS-SOLUTION OF MERCURIC NITRATE.

HYDRARGYRI CHLORIDUM CORROSIVUM-MERCURIC CHLORIDE. Are these medicines escharotics?

The uses of these substances as caustics will be found under Zinc (v. "Astringents") and Mercury (v. "Alteratives").

POTASSII BICHROMAS-POTASSIUM BICHROMATE.

What is potassium bichromate ?

It is an irritant internally, and in overdoses a corrosive poison. Externally it is a caustic, used to destroy syphilitic condylomata, warts, etc. Internally it is used as an alterative in doses of gr. (0.013) t. i. d.

THE MINERAL ACIDS.

Are the mineral acids used as caustics?

The mineral acids are powerful caustics, and are often employed to remove warts, or other excrescences, to cauterize chancres, indolent sinuses and ulcers. Nitric acid is preferred as an escharotic.

SILVER NITRATE, COPPER SULPHATE, and ALUM have all been previously spoken of as caustics under their appropriate heads.

Class III.-Demulcents.

What are demulcents?

Demulcents are bland remedies which, when applied to inflamed or irritated surfaces, exert a soothing influence upon them and are employed internally for this purpose. They are used in acute inflammations of the alimentary canal; in pharyngeal, laryngeal and bronchial irritation; in renal, cystic, and urinary affections generally; and to suspend medicinal substances which are insoluble in water. They are also used as light articles of diet.

Describe the demulcents.

AQUA (water) is used in medicine in its purest attainable state, i. e., rain or melted snow. For pharmaceutical purposes it should only be used in the form of distilled water (aqua destillata). A certain amount of water is necessary for the proper performance of the functions of the body. It is an active diuretic, increasing not only the watery, but also the solid ingredients of the urine. It is eliminated by the kidneys, skin, lungs and bowels. It is used as a diuretic in acute renal diseases, and is also often serviceable in chronic Bright's disease. To dilute a highly concentrated urine in ardor urinæ, especially when there is a tendency to the formation of gravel or calculi, it is invaluable.

It is useful in fevers, as it aids the elimination of the waste products. Externally, it is used in the form of baths, either hot ŵr cold, not only for purposes of cleanliness, but also as a therapeutic agent. Impregnated with carbonic acid gas under pressure, it makes an agreeable drink known as soda-water, which is often useful in allaying nausea and vomiting.

ACACIA, or gum arabic, is a gummy exudation from Acacia Senegal (Nat. Ord. Leguminosa), a tree of Africa. It contains arabic acid, and is much used in solution as a demulcent in various forms of sore throat. It is also used in making emulsions and pills.

Its preparations are: a mucilage (mucilago acacia) and a syrup (syrupus acacia). Emulsion of almonds (emulsum amygdala) is an agreeable form for administration.