This is sometimes, though rarely, administered in substance, in the form either of pill, or of electuary made with sugar. The dose is the same as that of the turpentines. But the form in which tar is almost exclusively used internally is that of infusion, or tar water. The mode of preparing this has been already described (II. 632). it is only necessary here to state that, being less stimulant than copaiba or the turpentines, it may be used in cases which might be thought to have too much acuteness for those medicines, or in which the propriety of using them might be deemed equivocal. From one to two pints may be given daily.

But it is by means of inhalation that tar is most useful; and, employed in this way, it is an excellent remedy in pectoral diseases, not only bronchial and laryngeal, but also pulmonary, not only in the chronic, but also in the acute in their advanced stages, when the expectoration is purulent and somewhat copious, and the system generally enfeebled. in pneumonia, which has advanced to the stage of abscess, in gangrene of the lungs under similar circumstances, in chronic bronchitis and ulcerative laryngitis, it may be used often with great benefit; and even cases of phthisis may be sometimes alleviated. But the remedy must be used long and continuously; for months, and, if necessary, for years. The vapour should never be so concentrated as to irritate or oppress the lungs; but should rather produce an agreeable impression upon them. The remedy is best administered by evaporating tar in a water-bath, so that the heat cannot be pushed so far as to decompose it. This may be conveniently accomplished by means of the nurse-lamp. (See vol. i. p. 74.) if the patient be confined to the house, the air of the apartment in which he sits or sleeps should be kept constantly impregnated with the vapour; and, if at home only at nights, he should breathe this medicated air the whole night in his chamber.