This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
A bituminous liquid obtained from the wood of Pinus sylvestris and other pines by destructive distillation.
Composition.-Tar is a variable mixture of creasote, phenol (carbolic acid), toluol, xylol, acetic acid, turpentine, resin, etc.
Dose.-20 to 60 min. in pill.
Preparation. Unguentum Picis Liquidae.-5 in 7.
Tar, being a compound of creasote, carbolic acid, and other substances, possesses an action very similar to the first two of these bodies, to which the student is referred. Its exact composition being variable, the action of tar is uncertain; and internally it is now but little employed.
Externally, it is more valuable than either of its important constituents, as a vascular stimulant and alterative in dry skin diseases, such as chronic eczema and psoriasis; and as a nervous sedative in prurigo and other kinds of itching.
Internally, tar may be given in pills, in capsules, or as tar-water, made by shaking up a pint of tar with half-a-gallon of water, and decanting after settlement-a very popular panacea a hundred years ago. Tar may still be used as a disinfectant in the stomach and bowels (see Creasotum, page 172), and as a remote disinfectant and deodorant in foul discharges from the bronchi and lungs, through which it is probably in part excreted.