(From the Pinus Sylvestris.)

Physiological Action. - Large doses of tar cause vomiting purging, violent pains in the bowels and across the kidneys, with diarrhoea and extreme exhaustion. When large doses have been taken, the pulse appears to be depressed, but not increased in frequency, while tar-water in small doses is said to quicken the pulse, and to act both as a diuretic and a sudorific. When the vapor of tar is inhaled, it increases the secretion from the bronchial mucous membrane. Taylor (on Poisons) reports some fatal cases of poisoning by tar.

Therapeutic Action. - Tar may be used internally in chronic catarrhal affections, especially in chronic bronchitis. It diminishes the secretion and allays the cough. It is also valuable in tubercular phthisis, acting as an expectorant, soothing the cough, and relieving the oppression; at the same time it helps the digestive system, increasing the appetite: and if colliquative diarrhoea be troublesome it tends to remove it. On the other hand, tar frequently overcomes constipation. It is very valuable in complaints of the urinary passages, such as chronic vesical catarrh; this latter affection is greatly improved by daily injections of tar-water into the bladder. Its use in certain chronic diseases of the skin has long been known. The tar-ointment quickly relieves the itching of scabies, and cures the disease in ten or twelve days. It is also used in psoriasis, eczema, and herpes circinatus (ringworm) with good effect. Trousseau recommends it strongly for prurigo. In unhealthy ulcers tar-water dressing has been extensively and successfully resorted to. As a disinfectant and deodorizer it has been most beneficially employed. Inhaled, as before stated, the vapor is useful in alleviating chronic bronchitis and other pulmonary affections; in acute inflammations and hectic fever its use should be avoided. In pulmonary affections the steam of tar-water from a vaporizer is the most useful mode of inhalation. It not only increases the bronchial secretions where the mucous membrane is dry and inactive, but, in other cases, diminishes it where the secretion is already too profuse.

Preparations and Dose. - Infusum Picis Liq.,

Tar Pix Liquida 12

- i. (15. -

30.); Glyceritum Picis Liq., 3 ss. - ij. (2. - 8.); Ungt. Picis Liquidae.