The ordinary method of administration is by means of an air-tight bladder, with a tube and mouth-piece attached, through which the patient breathes, inhaling the contents of the bag, and returning into it the air from the lungs; the nostrils being closed during the process. Though the effects of the gas may be obtained in this way,yet it is liable to the objection, that the same air is constantly breathed over again; and, as the carbonic acid from the lungs is steadily increasing, and the nitrous oxide as steadily diminishing, it must happen at length, if the process be long continued, that the air breathed will be chiefly the former gas, and asphyxia may be endangered from this cause. To obviate the chance of this evil, the bag should be large enough to hold all the gas required to produce the anaesthetic effect; and, instead of one or two gallons, which is often its capacity, should contain several gallons, not less, according to Dr. Spears, than six or eight, though this would probably, in general, be considered unnecessarily large. (Med. and Surg. Reporter, Feb. 10, 1866, p. 118.) But a still better plan is to use a bag with a valve in the tube opening outward, so as to permit the entrance of the air of the bag into the lungs, but to prevent the return of the expired air into it. When the operation is carried on very largely, as in the office of a dentist, it will be convenient, in order to ensure at once a sufficient supply of the pure gas always on hand, and the greatest convenience of administration, to be provided with an apparatus both for the preparation and preservation of the gas; including the retort with the means of heating it, several bottles containing the purifying liquids through which the gas is to pass successively, and a large reservoir or gasometer of zinc, which may receive the gas as generated, and retain it for use. With this gasometer a tube may be connected, furnished with a valve opening outward, through which the patient may inhale the gas without returning a particle to the reservoir*

Nitrous Oxide Water. The aqueous solution of the gas without press-ure, containing from three-quarters to an equal bulk of the gas, was tried internally by Sir. H. Davy, who believed it to promote digestion, and to act as a diuretic. An oversaturated solution made under press-ure, and containing five volumes of the gas for one of water, was patented in England, where it was known as Searle's oxygenous aerated water, and has been used to some extent as an internal remedy. By Serullas it was thought to be useful in Asiatic cholera. In this country. the internal use of nitrous oxide water has been especially investigated by Dr. Geo. J. Ziegler, of Philadelphia, who made various experiments both on the human subject and the lower animals, and published the results of his researches. The solution taken into the Stomach, or injected into the bowels, appears to exercise in some degree the stimulant and exhilarating effects of the gas inhaled, at the same time that it produces a gently excitant effect on the mucous membrane, and by absorption to improve the blood, when deficiently oxygenated. Among other effects which it has in common with the inhaled gas, is that of obviating asphyxia from various causes, by at the same time oxidizing the blood and stimulating the nervous centres and the heart. The diseases in which the nitrous oxide water has been employed, with supposed advantage, or may be used with hope of benefit, are dyspepsia; depression of spirits; general torpor and debility; neuralgia connected with debility; gastralgia; asthma; syncope; threatened or existing asphyxia; the debility following the excitement of the stimulating narcotics, as opium, alcohol, ether, etc., and that attending the immediate action of the cerebral or nervous sedatives, as chloroform, hydrocyanic acid, digitalis, tobacco, aconite, etc.; and, finally, the low condition of all fevers requiring stimulation, in which this remedy is particularly indicated, as not being followed by depression. Dr. Chapelle, of Angouleme, in France, has found the remedy especially beneficial in lypemania, or that form of monomania in which the delusion is attended with depression of spirits or melancholy. (Arch. Gen., Juin, 1865, p. 739.) According to the observations of Dr. Ziegler, its long-continued use occasions emaciation, resulting from the too rapid oxidation and consequent excess of the vital changes of the tissues; but this condition is much less serious than that proceeding from an opposite cause, as it indicates no depreciation of the vital powers. Indeed, the remedy may be used, in case of morbid obesity, with a view to this very effect.

* For an account, with a figure, of an apparatus, contrived by Prof. Vander Weyde, and described by Dr. Sam. W. Francis, of New York, see the Medical and Surgical Reporter (May 19, 1866, p. 382).

Where it cannot be taken by the mouth, it may be administered with similar results by the rectum. From half a pint to a pint and a half of the nitrous oxide water may be taken, in wineglassful doses, less or more, through the day. Three times the quantity may be given by enema.

Peroxide of Hydrogen

Peroxide of Hydrogen. Some attention has recently been attracted to peroxide of hydrogen as an oxidizing agent in the system, and as a remedy of diversified powers, by the experiments and researches of Dr. Richardson, of London; but it has not yet practically obtained such a position in therapeutics, as to authorize its adoption into the catalogue of remedies. Further trials may justify, or perhaps even exceed the hopes entertained in relation to it. At present I must content myself with referring to the U. S. Dispensatory (12th ed., p. 1579), where an abstract will be found of all that is at present known concerning it in a remediate capacity.