Tar, Pine Tar.
A liquid obtained by the destructive distillation of the wood of Pinus palustris, Miller, and other species of Pinus (Nat. Ord. Pinaceae).
Description.—A blackish-brown, viscid, semi-liquid, amorphous substance, but gradually becoming granular and opaque; odor empyreumatic and terebinthinate, taste sharp and tarry. Slightly soluble in water, with a brownish color and acid reaction. Mixes with alcohol, ether, chloroform, and oils. Upon distillation it yields oil of tar and pyroligneous acid. Dose, 5 to 15 grains.
Principal Constituents.—Oil of turpentine, creosote, phenol, catechol, xylol, toluol, acetic acid, acetone, methyl alcohol, and at least ten resins.
Preparations.—1 Oleum Picis Liquidae Rectificatum, Rectified Oil of Tar. Dose, 3 to 5 minims.
2. Aqua Picis Liquidae, Tar Water. Dose, 1 to 3 fluidounces every four to six hours.
3. Syrupus Picis Liquidae, Syrup of Tar. Dose, 1 to 2 fluidrachms.
Action.—Tar is irritant and antiseptic. Upon prolonged application tar acne may ensue, and in some instances it has produced poisoning similar to that of phenol. Internally it excites the circulation and the secretions, especially of the kidneys and lungs, and acts as an antiseptic to those tracts, thus proving diuretic, disinfectant and expectorant. Overdoses produce headache, indigestion, black vomit and stools, and blackish urine with blood and albumen and a decided tar-like odor.
Therapy.—External. Tar is chiefly used as an antipruritic and antiparasitic. It is of use in scaly skin diseases, and in various preparations it has been applied in psoriasis, chronic eczema, prurigo, porrigo, lichen, sycosis, lupus vulgaris and erythematosus, pemphigus, tinea capitis and other forms of ringworm, scabies, and boils. Some persons are very susceptible to tar, an erythema following the application of even dilute preparations of it.
Internal. Tar water, or syrup of tar, may be used in bronchial cough, and to prevent the recurrence of boils, in chronic urinary catarrhs, and in eczema and psoriasis (together with its external use). Tar should not be given to those having a disposition to hemorrhages. Syrup of wild cherry added to tar water or the syrup of tar makes a useful cough remedy for chronic bronchitis.