used as an intestinal antiseptic. It is often advantageously combined with bismuth subnitrate and sodium bicarbonate.

FORMALDEHYD.

What is this substance?

Formaldehyd, or formic aldehyd (not official), is an aqueous solution containing 40 per cent. of formalin or formal, obtained by oxidation of methyl alcohol. It forms a colorless solution having a pungent odor and taste. It has been much used as a deodorant and disinfectant and is said to be poisonous in a very moderate degree. Concentrated solutions applied to the skin are said (R. H. Cunningham) to cause a peculiar necrosis, unaccompanied by signs of inflammation. The gas is liberated by heating the solution, and it is said that an atmosphere containing 2.5 per cent. of the gas is speedily fatal to all micro-organisms.

It has been used to disinfect the surgeon's hands and instruments, in the preparation of aseptic catgut ligatures, and in dilute solutions (1: 2000) in the treatment of gonorrhoeal affections of the female. In the male it has sometimes effected a cure in acute gonorrhoea, more frequently when the disease was situated in the deeper parts of the urethra. Occasionally the irritation caused by its use was so great that the irrigation had to be discontinued. It has also been used in solutions of the same strength in acute conjunctivitis. Recently it has been recommended as a spray (1 per cent. solution, in the treatment of pertussis, and, used in the same manner, is strongly recommended in the treatment of hay asthma.

THE ANTIPYRETICS AND ANTISEPTIC OILS.

Are these substances used as antiseptics?

The antipyretics (q. v.) have been sufficiently considered.

The antiseptic properties of the volatile oils classed with the Carminatives" (q. v.) have been alluded to under that head. Those of importance not hitherto mentioned are:

What is thymol?

THYMOL.

Thymol (cymylic phenol) is a crystalline substance found in the oil of thyme (oleum thymi) (q. v.). Locally it is a powerful antiseptic and

local anesthetic.

Given internally it lowers febrile temperature to some extent, and causes diaphoresis. In excessive amount it causes tinnitus aurium, deafness, diarrhoea, and sometimes delirium and collapse. It is used as an antiseptic gargle and mouth-wash in aphthous and diphtheritic ulcers of the mouth and fauces, and internally as a gastric sedative to allay vomiting. As an anti-fermentative, in flatulency from fermentation of the food and in intestinal indigestion, it is very useful. Dose gr. ss-ij (0.03-0.13). As much as gr. xxxxx (1.2-2.0) have been given in 24 hours. It is administered in solution in glycerin, alcohol, and water.

Class II.-Irritants.

What are irritants?

Irritants are medicines which are used locally to produce counterirritation or inflammation of the parts to which they are applied. They are divided, according to the violence of their action, into Rubefacients, Vesicants, Suppurants, and Escharotics or Caustics.

ORDER I.-RUBEFACIENTS.

What are rubefacients?

Rubefacients are medicines which are employed to produce a powerful but temporary irritation and congestion of the surface. They are useful in arousing the system in shock; in stimulating the circulation of a part in case of frost-bite, or to aid in bringing on reaction in the cold stage of a congestive chill; in all cases of congestion and in the formative stages of inflammations. The application of rubefacients for the relief of neuralgic and muscular pains is often followed by improvement which may even be permanent.

Mention the principal rubefacients.

Mustard; capsicum; oil of turpentine; ammonia; Burgundy pitch, and Canada pitch.

SINAPIS ALBA-WHITE MUSTARD.

SINAPIS NIGRA-BLACK MUSTARD.

What is mustard?

Mustard is the seed of Brassica alba, or white mustard, and B. nigra, or black mustard (Nat. Ord. Cruciferæ).

What chemical principles do they contain?

Mustard seed contains a fixed oil. Black mustard seed yield on distillation a volatile oil (allyl sulphocyanide) which does not preëxist in the seed, but is formed by the action of water on sinigrin or potassium myronate. The white seed yield an acrid fixed principle which is formed by the action of water on sinalbin. These changes are probably due to the presence of myrosin, an albuminous ferment.

What are the effects and uses of mustard?

Locally, it is an irritant rapidly causing redness and a sensation of heat; if the application is long continued, inflammation and even gangrene may result. Internally it is a stomachic in small doses, an emetic in larger amounts, and a severe gastro-intestinal irritant if an excessive quantity be taken.

Mustard is used as a rubefacient in the form of a mustard plaster (made of the powdered seed known as mustard flour), whenever a mild counter-irritant effect is desired. The mustard should not be allowed to come in contact with the skin, but should be separated from it by a piece of gauze or a fold of muslin or newspaper. When a prolonged but gentle effect is desirable, the mustard may be added to a flaxseed poultice or diluted with flour. Internally, mustardflour is used as an emetic, and is especially valuable when torpor of the stomach is present.

What are the preparations of mustard, and their doses? The dose of powdered mustard as an emetic is 3j-iv (4.0–16.0). The official preparations are mustard-papers (charta sinapis), a convenient form for external use. Each square inch of paper contains about gr. vj of black mustard deprived of its oil. They should be dipped in warm water before applying. The volatile oil (oleum sinapis volatile) is very irritant, and is used in preparing the compound liniment (linimentum sinapis compositum).

CAPSICUM. OIL OF TURPENTINE. AMMONIA. Are these substances used as rubefacients?

The uses of these substances as rubefacients will be found in detail under the respective drugs.

Linimentum ammonia (liniment of ammonia) contains 3.5 per cent. of ammonia water in cotton-seed oil and alcohol.

PIX BURGUNDICA---BURGUNDY PITCH.

What is Burgundy pitch?

Burgundy pitch is the prepared resinous exudation from Abies excelsa, or Norway spruce (Nat. Ord. Conifera). It contains a resin and a volatile oil, and is a mild rubefacient, used in the form of plaster in subacute and chronic bronchitis, to the back in lumbago, and to the joints in chronic rheumatism.

Pitch plaster with cantharides (emplastrum picis cum cantharidê) is more stimulating than the plaster (emplastrum picis Burgundica). Iron and opium plasters contain Burgundy pitch.

ORDER II.-VESICANTS.

What are vesicants?

Vesicants are remedies which, when applied to the skin, cause sufficient inflammation to produce an effusion of serum under the cuticle, or, in other words, to raise a blister. They are also called epispastics, or blisters. They are used in inflammations of the serous membranes, especially when accompanied by an outpouring of serum; to deplete the vessels in inflammations of the brain and its membranes; in chronic joint affections; in neuritis, and for the relief of various neuralgic pains, and are sometimes used in inflammations of the parenchymatous viscera. They are contraindicated in the very young or very old, where there is great depression of the vital powers, or where there is very high arterial tension.

Name the principal vesicants.

Spanish fly, potato fly, and stronger water of ammonia.

CANTHARIS-CANTHARIDES.

What is cantharides?

Cantharis vesicatoria or Spanish fly (Class, Insecta; Order, Coleoptera) is an insect found in the temperate parts of Europe, but especially in Spain and Italy. When dried they contain a volatile oil and a neutral crystalline principle, cantharidin, the vesicating principle. What are its effects and uses?

Locally, cantharides is an intense irritant to any surface with which it comes in contact; thus, applied to the skin it causes inflammation of sufficient intensity to result in a serous effusion under the cuticle, and if the application be too long continued, gangrene may result. Constitutional effect may be caused from the local application of cantharides. Internally, in small doses, it is diuretic; in larger amounts it is an irritant, causing pain on urination, priapism, strangury, and even bloody urine. Sexual desire does not usually occur, In excessive doses it is a gastro-enteric irritant, causing