This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
These, when applied externally, stimulate the skin, and thus cause redness, sometimes even vesication, tingling, and subsequent numbness. Taken internally, they stimulate the gastro-inteslinal tract, increasing its vascularity, the flow of saliva, of gastric juice, and of succus entericus; and they excite its unstriped muscular fibres. Thus in moderate doses they are stomachics and carminatives; in large doses they are gastro-intestinal irritants. Their irritation of the stomach reflexly stimulates the heart and the central nervous system. They are absorbed and excreted by the skin, which they may thus irritate, and by the bronchial mucous membrane, while they consequently stimulate, increasing the amount of secretion from it, its vascularity, the expulsive power of its unstriped muscles, and reflexly this irritation leads to coughing; consequently they are expectorants, although they may later limit the amount of secretion formed. They are also largely excreted by the kidneys, which are stimulated even to inflammation, and hence these drugs are often diuretic; and by the genito-urinary mucous membrane, which is also stimulated, often so energetically that it may become inflamed. Some are antiseptic Some volatile oils act strongly in all these ways; others act much more powerfully in some than in others. Volatile and fixed oils are usually mutually soluble in all proportions. Volatile oils are generally slightly soluble in water.
They will be classified according to the tissue on which they chiefly act, or for the action for which they are mostly used.
Class I. - Volatile oils (or substances containing them), acting chiefly upon, or used chiefly for their stimulation of the skin.
Turpentine, Oil of Turpentine, Oil of Erigeron, Pix Liquida, Oil of Cade, Burgundy Pitch, Resin, Frankincense, Canada Turpentine, Mustard, Oil of Cajuput, Eucalyptus, Oil of Rosemary, Arnica, Mezereum, Elemi.
Class II. - Voladle oils (or substances containing them) acting chiefly upon, or used chiefly for their stimulation of the gastro-intestinal tract.
Pyrethrum, Cloves, Pimenta, Pepper, Nutmeg, Mace, Cinnamon, Horseradish, Capsicum, Ginger, Cardamom, Sumbul, Oil of Lavender, Oil of Lavender Flowers, Oil of Bergamot, Peppermint, Spearmint, Anise, Illicium, Coriander, Fennel, Caraway, Dill, Sam-bucus, Oil of Pennyroyal, Absinthium, Chamomile, Matricaria, Rose.
Class III. - Volatile oils (or substances containing them) acting chiefly upon the stomach, so as to reflexly stimulate the heart and central nervous systems, or chiefly used for this purpose.
Class IV. - Volatile oils (or substances containing them) acting chiefly upon, or used chiefly for their stimulation of the bronchial mucous membrane.
Class V. - Volatile oils (or substances containing them) acting chiefly upon, or used chiefly for their stimulation of the kidneys and genito-urinary tract.