An empyreumatic oleo-resin obtained by the destructive distillation of the wood of various species of pines, especially that of Pinus palustris. HABITAT.--United States. PROPERTIES.--Thick, viscid, semi-fluid, blackish-brown; heavier than water, transparent, in thin layers, becoming granular and opaque with age; odor empyreumatic terebinthinated; taste sharp empyreumatic. Tar is slightly soluble in water; soluble in alcohol, fixed or volatile oils and solutions of potassium or sodium hydrate. CONSTITUENTS.--Oil of turpentine; methylic alcohol; creosote; guaiacol; phenol; pyrocatechin; toluol; xylol; acetic acid; acetone; resins. DOSE.--Horses and cattle, ¹⁄₂ to 1 oz.; sheep and pigs, 1 to 2 dr.; dogs, ¹⁄₄ to 1 dr. Oil of tar should be diluted with alcohol, glycerine, syrup or mucilage. PREPARATIONS UNGUENTUM PICIS LIQUIDAE--TAR OINTMENT Composed of tar, 500; yellow wax, 150; lard, 350. Used alone as a healing ointment or as a base. OLEUM PICIS LIQUIDAE--OIL OF TAR A volatile oil distilled from tar. PROPERTIES.--An almost colorless liquid when freshly distilled, but soon acquiring a dull, reddish brown color, and having a strong tarry odor and taste. Soluble in alcohol. DOSE.--Horses and cattle, 1 to 2 oz.; sheep and pigs, 2 to 4 dr.; dogs, ¹⁄₂ to 2 dr. ACTIONS.--Internally, is an antiseptic stimulant expectorant. Externally, it is rubefacient and if continually rubbed in may cause papules and pustules. USES.--Tar or the oil is commonly used in cough mixtures and in subacute and chronic bronchitis. By inhalation (which is done by pouring tar on a heated shovel or a shovel containing live coals or by adding a pint of tar to a gallon of water, heating the mixture by placing hot bricks or stones in the solution) either method is excellent for its local antiseptic and stimulating effects in the various catarrhal diseases; bronchitis, distemper, strangles, etc. Care should be used so that the vapor be not inhaled too hot. Externally, it is a very useful agent in various skin diseases, both parasitic and non-parasitic; for this the official ointment may be used, or if used on a large surface on dogs it should be diluted with an equal amount of zinc ointment. PLUMBI OXIDUM--LEAD OXIDE DERIVATION.--Made by roasting lead in the air. PROPERTIES.--A heavy, yellowish or reddish-yellow powder, or minute scales, without odor or taste. Almost insoluble in water; insoluble in alcohol. Lead oxide is only valuable for its preparations. PREPARATIONS PLUMBI ACETAS--LEAD ACETATE--SUGAR OF LEAD DERIVATION.--Heat lead oxide in acetic acid and water. Lead acetate crystallizes on cooling. PROPERTIES.--Colorless, shining, transparent; monoclinic prisms or plates, or heavy, white crystalline masses, or granular crystals, having a faintly acetous odor and a sweetish, astringent, afterwards metallic taste. Efflorescent and absorbing carbon dioxide on exposure to the air. Soluble in two parts of water and in thirty parts of alcohol.