Ethyl Bromide. - A colorless, inflammable liquid, with a burning taste and an odor like that of chloroform. It is readily decomposed, with evolution of bromide. Its action is uncertain, causing great irritation of the respiratory passages, and usually producing death by paralysis of respiration.

Ethyl Iodide. - A liquid anesthetic, similar in its physiological action to chloroform. Anesthesia produced by it, however, is more tardy, although more permanent. It is considered a comparatively safe and efficient anesthetic to relieve spasm of the respiratory passages, as in asthma and laryngitis.

Ethylene Bichloride. - More rapid and powerful in its action than chloroform, though not so safe, affecting the respiratory center invariably before influencing the heart. While speedier in its action than ether, it is probably more dangerous.

Ethylene Bromide. - A weak yet dangerous anesthetic, greatly depressing the respiratory center, and tending to cause paralysis of the extremities and stoppage of the heart.

Ethylene Iodide. - A crystalline substance, its fumes when heated producing anesthesia, with great irritation of the respiratory passages, and death by asphyxia.

Ethylidene Chloride. - A non-inflammable liquid resembling chloroform in its physical appearance, and in its physiological action as well, although much less depressant to the heart. It causes more irritation to the respiratory passages, with vomiting and great languor and discomfort as its sequelae.

Methyl Chloride. - A colorless, inflammable gas, with a taste and odor resembling those of ether and chloroform. Cold liquefies it. It is used locally to produce anesthesia and to relieve pain in neuralgia.

Methylene Bichloride. - A colorless liquid, its odor being like that of chloroform. Exposure to the light decomposes it. Anesthesia produced by this agent is accompanied with comparatively little irritation of the respiratory tract, but it occasions a primary stage of excitement like that induced by ether, and, as in the case of chloroform administration, vomiting is likely to ensue. Death takes place from paralysis of the heart. The numerous fatalities which have occurred under this anesthetic indicate the danger of its use, and its volatility renders its employment difficult in a hot atmosphere.

Carbon Tetrachloride - Tetrachlormethane. - A transparent, colorless liquid, of an agreeable aromatic flavor, analogous in its action to chloroform, but less irritating, although far more dangerous to the heart.

Formic Ether. - A thin, colorless, inflammable liquid, of strong, agreeable odor and pungent taste. It acts like chloroform, though the signs of asphyxia are less marked. Its effects last for several hours.

Methylic Ether. - A colorless, inflammable gas, heavier than air, of an ethereal odor and aromatic taste. Richardson considers it a safe anesthetic, though objectionable because of its odor - less agreeable than those of ether and chloroform - and the rapidity with which it volatilizes from its solution.

Methylal - Methylene - Dimethyl Ether. - A highly volatile, colorless, limpid liquid, of penetrating ethereal odor. It is used chiefly as a local anesthetic and as an efficient hypnotic in insanity and delirium tremens.

Acetic Ether (U. S. P.). - A colorless, limpid, volatile liquid having an agreeable, refreshing, ethereal, and somewhat acetous odor and taste. It has the advantage over sulphuric ether of being less inflammable and less volatile. Owing to its pungent and agreeable odor, too, it is superior to the latter drug in stimulating the nasal passages in cases of syncope and nervous agitation.

Pental. - A colorless, volatile, inflammable liquid, insoluble in water, but miscible in all proportions with alcohol, ether, and chloroform. It has a mustard-like odor, and is comparatively free from danger. When poisonous amounts are administered the pulse is quickened, the respiration embarrassed, and death ensues from paralysis of the heart. It resembles chloroform rather than ether, but is less irritating and seldom accompanied with unpleasant aftereffects. It requires but about 5 drachms (20.0 Cc.) to produce anesthesia, which occurs in from two to three minutes.

There is a difference of opinion as to the safety of pental, some physicians considering it less dangerous than chloroform, and others regarding it as less efficient and not so safe.

Nitrous Oxide ("Laughing Gas"). - A colorless gas, of a very slight, agreeable odor and sweetish taste. It is not inflammable, but supports combustion of ignited bodies. Pressure and cold condense it into either a thin, colorless, very mobile liquid or colorless crystals. It is a rapid anesthetic, unconsciousness being produced in from one-half a minute to three minutes. The pulse is strong and quick, the respirations frequent and shallow, while, as the inhalation continues, the breathing becomes stertorous and the face is cyanotic. If the inhalation be interrupted or the gas mixed with air, symptoms of intoxication are manifested, accompanied with a high degree of mental excitement. It is a very safe anesthetic, but the anesthesia is of quite short duration, rendering it valuable mainly for the extraction of teeth and in minor surgery.