The bronchial mucous membrane, and the surface of the pulmonary air-cells, afford not unfrequently a ready entrance of medicines into the system, in consequence of the great facility of absorption through their delicate tissue. Indeed, some volatile medicines act much more rapidly and powerfully in this way than when taken into the stomach. The effects, for example, of ether and chloroform are familiar to every one. But the practical use of this avenue into the system is very much limited by the inconvenience, and even danger, of administering most medicines in that way. Some, it is true, have proposed to throw fine medicinial powders into the lungs by loading with them the respired air; but when the hazard is considered of exciting inflammation by such means in this delicate tissue, it must, I think, be admitted to outweigh any probable advantages. The substances to which this method is especially applicable are gases and vapours. Of these some have been employed to ad locally on the bronchial passages, as chlorine gas. the vapour of tar and iodine, and the fumes of burning rosin in chronic bronchitis, and ethereal vapour, the smoke of stramonium and tobacco, and the gases evolved by the burning of paper impregnated with nitre, in the asthmatic paroxysm. At present, however, attention is much more than formerly directed to constitutional impression; and various volatile substances have been employed for their exhilarating and anaesthetic effect. Aqueous vapour has been long and much employed by inhalation.

Inhalation may be effected in various way. One of the simplest is to Impregnate the air of the apartment in which the patient is confined with the gas or vapour. In this way a steady effect may be sustained. for a great length of time, by proper attention to the degree of impregnation, so as not to oppress the breathing. Even when the patient is not confined to the house during the day, much advantage will often accrue from medicating the air of his sleeping chamber. Chlorine and the vapour of tar may be thus administered; and I have witnessed the happiest effects from the latter remedy, continued for months, in very threatening chronic pulmonary disease. A convenient method, in the case of tar and other liquids hut moderately volatilizable, is to employ a common tin apparatus called the nurse-lamp, in which a cup, containing the material to be evaporated, is placed in a small water-bath over a spirit lamp.

Another mode, applicable to very volatile liquids, such as ether and chloroform, intended for temporary use, is to place them upon a large sponge, or piece of linen cloth, a handkerchief or towel for example, and apply this, fully charged, over the mouth and nostrils, so that the patient may inhale their vapour along with the atmospheric air Sometimes the saturated sponge is enclosed in an apparatus, so arranged that all the vapour which escapes from the liquid shall be inhaled, and thus unnecessary loss be prevented, while a due supply of atmospheric air is insured. In the exhibition of the narcotic vapours, it is of the utmost importance, in order to avoid the most serious consequences, to attend strictly to this latter caution. The patient, rendered more or less unconscious by the medicine, is not sensible of the want of air, and does not, therefore, give warning of his danger to the operators, as he would do under other circumstances. There can be little doubt, that death has sometimes resulted from an insufficient supply of atmospheric air, in this method of using anesthetic agents.

The pure gases, and the vapours of very volatile substances, such as ether, may also be inhaled by means of an air-tight bag, supplied with a mouth-piece and stop-cock, so as to regulate the escape of the confined gas or vapour. The patient is made to breathe into and out of the bag; but it is obvious that, unless there be a large admixture of atmospheric air or oxygen, life could be sustained but a very short time during such a process, which, therefore, should be of short continuance, and always carefully watched.

The vapour of water, pure or impregnated with various volatile matters, may be inhaled by means of an instrument called the inhaler. Mudge's inhaler, which has been much used for this purpose, consists of a pewter quart mug, with a metallic removable lid, in which is a small opening to admit the air, and another larger one to which a flexible tube with a mouth-piece is affixed. Water, alone or variously impregnated, is introduced into the instrument, which may then be placed in a vessel containing water, heated to whatever point may be necessary sufficiently to volatilize the confined liquid, the vapours of which are inhaled by the patient, along with the air admitted through the small opening. A better apparatus for the same purpose may be made from a Wolfe's bottle, with three tubulures at top, into one of which is fitted a flexible tube with a mouth piece, into a second a glass tube extending from the air without to a point beneath the surface of the liquid in the bottle, and into the third a glass stopper, to be removed when there is occasion to pour liquid into the bottle. It is obvious that, when the patient inspires, the air from without must pass through the liquid, and thus become more thoroughly loaded with the vapour than it would be likely to be in Mudge's inhaler. An extemporaneous inhaler may be made, as formerly suggested by Dr. Physick, by fitting a cork into any broad-mouthed common bottle, making three openings through the cork, and supplying these with tubes in the manner mentioned in reference to the Wolfe's bottle, only that the breathing tube may be straight, and, if glass is not at hand, common pipe-stems, or pieces of goose's quill, lengthened sufficiently by insertion into one another, may be substituted. As in the Mudge's inhaler, a proper temperature of the contained liquid may be maintained, if necessary, by setting the bottle in a water-bath. Besides those mentioned, several other inhalers have been invented, and more or less employed, all, however, acting on the principles referred to *