Rubefacients and Epispastics.

Sinapis, Mustard,—the seeds of Sinapis alba and Sinapis nigra.

Composition of the Mustards.

Sinapis alba contains:

Sinalbin

Myrosin, a ferment.

Acrinyl Sulphocyanate is the rubefacient principle,—produced by reaction between these two in the presence of water.

Sinapine, an alkaloid.

A bland, fixed Oil.

Erucic or Brassic Acid.

Sinapis nigra contains:

Sinigrin (Pot. Myronate).

Myrosin, a ferment.

Allyl Sulpho-cyanide, the Volatile Oil of Mustard, produced by reaction between these two in the presence of water.

Sinapine, an alkaloid.

A bland, fixed Oil.

Erucic or Brassic Acid.

Pix Burgundica, Burgundy Pitch,—See ante, page 217.

*Pix Canadensis, Hemlock Pitch,— See ante, page 217.

• Emplastrum Picis Burgundicae, Burgundy Pitch Plaster.
• Emplastrum Picis Cantharidatum, Cantharidal Pitch Plaster.

Pix Liquida, Tar,—an empyreumatic oleo-resin. (See ante, page 217.)

• Oleum Picis Liquidae, Oil of Tar,—soluble in alcohol.

Camphora, Camphor. (See page 119.)

• Linimentum Camphorae, Cotton-seed Oil 8, Camphor 2.
• Linimentum Saponis, Soap-liniment,—Soap 7, Camphor 4 ½ , Oil Rosemary 1, Alcohol 75, Water q. s. ad 100.

Terebinthina, Turpentine. (See page 215.)

• Oleum Terebinthinae, Oil of Turpentine, Spirits of Turpentine,—is soluble in 3 volumes of alcohol. (See ante, page 216.)
• Linimentum Terebinthinae, Turpentine Liniment,—has of the Oil 35 parts with Resin Cerate 65.

Cantharis, Cantharides, Spanish Flies,—the beetle Cantharis vesicatoria, an insect of the order Coleoptera.

• Tinctura Cantharidis, ♏︎j-xx.
• Collodium Cantharidatum.
• Ceratum Cantharidis.
• Emplas. Picis Cantharidatum.

Capsicum,—is the fruit of Capsicum fastigiatum, Cayenne Pepper, a plant of the nat. ord. Solanaceae, to which Belladonna, Stramonium, Hyoscyamus and Dulcamara also belong. Contains an alkaloid resembling Coniïne in odor, and a thick, red liquid, Capsicin, which is the active principle. Capsicum in powder is often adulterated with red lead.

• Tinctura Capsici,—Dose, ♏︎v-ʒj, as a gargle ʒss-ij in ℥vj.
• Extr. Capsici Fl., ♏︎j-xxx.
• Emplastrum Capsici,—is a most excellent plaster.
• Oleoresina Capsici,—Dose, ♏︎j-v.

Menthol, Peppermint Camphor,—(See ante, page 194).

Epispastics.

Cantharis, Cantharides, (See above), in some one of its forms, is the agent in general use for the purpose of blistering. Other efficient epispastics are—

• Mezereum.
• *Euphorbium.
• Glacial Acetic Acid.
• Stronger Ammonia Water,—the confined vapor.
• Volatile Oil of Mustard.

Pustulants.

Oleum Tiglii, Croton Oil,—(See ante, page 207).

Antimonii et Potassii Tartras, Tartar Emetic,—(See page 71).

Physiological Action. The action of irritants upon the circulation of an inflamed part is very similar to that of heat or cold, in that the result of either application is the relief of tension in the vessels, and consequently the relief of pain and decrease of inflammation. Heat acts directly, dilating the capillaries of the collateral circulation, and thereby diverting the current from the inflamed area. Cold acts indirectly, causing reflex contraction of the afferent vessels, and diminishing the supply of blood to the inflamed part. Irritants cause dilatation of the vessels of the part to which they are applied, but contraction of the vessels in other parts of the organism, especially in those parts or organs which have a nervous connection with the part or organ irritated. Counterirritation acts upon this principle, and to be most effectual, should not be applied directly over the organ inflamed, or even too near it, lest it should increase the congestion instead of diminishing it. By increasing the activity of the circulation in their immediate vicinity, counterirritants also promote the reabsorption of inflammatory products; and when employed for this purpose they should be applied directly over the organ or tissue affected.

Therapeutics. Counterirritation, when intelligently employed in accordance with the above-mentioned principles, is an exceedingly efficient and valuable measure for (a) the relief of pain,—(b) the decrease of local inflammation,—and (c) the reabsorption of inflammatory products. Hence its applications are very numerous, and its area of employment a very wide one, admitting only the citation of a few instances to serve as illustrations. In—

Pericarditis,—a blister upon the thoracic wall, at some distance from the praecordia, will help to lessen congestion and consequently to lower the inflammation.

Pericardial Effusion,—to promote absorption, the blister should be placed directly over the praecordia.

Pneumonia,—to promote reabsorption after consolidation, a blister directly over the affected part, or an energetic rubefacient.

Neuralgia, of superficial nerves,—may be controlled by blisters over the painful nerve;—or over the spinal column at the "tender point" corresponding to the intercostal nerve affected;—or to the heel in sciatica. The actual cautery is often still more efficient.

Vomiting from any cause,—is always helped by a blister or a rubefacient application over the epigastrium.

Chronic Ulcers,—vesicants locally, about the site of the ulcer, have a curative influence in many cases resisting ordinary treatment.

Joint Effusions, or thickening,—the only treatment of any value is that by vesicants or the actual cautery, in the vicinity of the affected part.

Acute Rheumatism,—blisters around the joints are of great value not only for the local inflammation, but also for the general disease, upon which they often have a curative influence.

Chronic Bronchitis and Pleurisy,—pustulants over the chest, in order to keep up a continuous moderate irritation.

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.