Ether, in chemistry, the name given to a class of highly volatile, inflammable, spirituous liquids, possessing a sweetish taste and peculiar fragrance, obtained commonly by distilling alcohol in mixture with some acid. Their composition is somewhat variable according to the acid employed in their preparation, and this gives them their distinctive names, as sulphuric ether, nitric ether, etc. Yet these acids do not in all cases furnish any of the ingredients of the ether, and the same ether may sometimes be produced by the action of other substances upon alcohol, as well as of the acid usually employed. This is especially the case with sulphuric ether, and as it contains no sulphuric acid, and is by far the most common form of ether, it is now admitted into the United States and London pharmacopoeias by the name of aether, as it was before known in common use. This ether, it is supposed, was known to Raymond Lully, who lived in the 13th century. Valerius Cordus in 1540 described the method of making it.

Frobenius in 1730 first brought it prominently forward in a paper published in the "Philosophical Transactions;" and by a note appended to this, it appears that Boyle and Newton had both directed their attention to it. - The preparation of ether was formerly conducted by distilling in a glass retort a mixture of equal parts of sulphuric acid and alcohol at a moderate heat, and, when about one third of the whole had come over, adding half as much alcohol as before, and again distilling. But a better method is to conduct the process on a larger scale with the use of a leaden still heated by high steam passed through in a spiral pipe; and the alcohol is best introduced in small quantities at a time by a pipe which passes through the upper part of the still. Such is the apparatus used at the apothecaries' hall, London. The heating by steam obviates the danger of explosion, to which the process is liable when the vapors that escape come in contact with a flame. The apparatus given by Brande is convenient either on a large or small scale. In a glass flask are introduced 8 parts by weight of concentrated sulphuric acid and 5 parts of spirit of wine of specific gravity 0.834. This is set in a small sand bath, which may be conveniently heated by a gas light.

A thermometer graduated at least to 320° F. passes through the cork, the bulb being in the liquid. There is also a tube reaching to the bottom, and expanding at top into a funnel. This is intended to receive more alcohol slowly dropped into it as the process goes on. A glass tube of large bore conveys the vapor through the condenser, which is surrounded with cold water, and the liquid drops from the end of the tube into a proper receiver. By keeping the temperature as nearly as possible to 300°, the ebullition goes on rapidly, and the quantity of liquid in the flask may be kept nearly the same for several hours, the alcohol as fast as it is admitted being converted into the vapor of ether and of water. These condense together, but in the receiving vessel they separate, the water sinking to the bottom together with 1/10 of its volume of ether dissolved in it. If a weak acid be used or too much alcohol, so that the boiling point of the mixture is reduced below 260°, the alcohol is apt to pass over unchanged. It is important to keep up a rapid, or even violent boiling, at a temperature between 260° and 310°. At about 320° olefiant gas and other undesirable products are generated.

By the continuous process of Dr. Brande, a small quantity of sulphuric acid may be made to convert into ether a large quantity of alcohol. It might serve for an indefinite time but for its slow volatilization and the passing over of its vapor with the others. Ether is purified by shaking it in a close vessel with twice its bulk of water. After standing, the ether is poured off, and the water that may be still present is taken up by mixing quicklime with it. Then by distilling, pure ether is obtained. - Ether is remarkable for its great volatility. Its vapor escapes in pouring the fluid from one vessel into another, so that if a lighted candle is near there is danger of the whole being suddenly inflamed. A mixture of 10 volumes of oxygen and one of ether vapor explodes violently by an electric spark. The vapor is so much more dense than air, being as 2.58 to 1, that it can be poured out of one vessel into another, displacing the air in this, and showing its presence by taking fire on the application of a match. Its rapid evaporation produces intense cold; a few drops being: made to cover a drop of water and then blown upon through a tube, the water is frozen directly. Ether itself, however, does not freeze, even at 166° below zero.

Its boiling point varies with the nature of the vessel containing it; at the ordinary pressure it boils at 96.5°. Its specific gravity at 68° is 0.713. It has neither an acid nor alkaline reaction; but after being exposed to the air and light, a little acetic acid is formed in it. Ether unites with alcohol in all proportions. It takes up 1/10 of its volume of water, and water does the same of ether. If water dissolve more than this, the ether may be suspected of being adulterated with water and alcohol. The ultimate constituents of sulphuric ether are carbon 4 equivalents, hydrogen 10, and oxygen 1, or C4H10O. The radical ethyle consists of C2H5, and ether is regarded as its oxide, alcohol as its hydrated oxide. - Various preparations of ether are largely employed in medicine, surgery, and obstetrics. When administered by the stomach they are stimulant and antispasmodic. Some of them have been used in fevers and nervous affections, and in other diseases to relieve spasm, nausea, and vomiting. Ether has also been administered to remove intestinal worms, which it is supposed to stupefy and cause to relax their hold. By far the most important preparation of ether is the concentrated sulphuric ether, used by inhalation to produce anaesthesia and muscular relaxation.

It is indicated whenever these objects are to be attained, as in the case of operations, surgical and obstetric, in hernia, stricture, dislocations, fractures, neuralgia, tetanus, dysmenorrhoea, colic, convulsions, feigned diseases, etc. The use of ether by inhalation to produce intoxication and to relieve pulmonary distress was known long before its anaesthetic properties were discovered. These were first practically demonstrated Oct. 16, 1846, when sulphuric ether was administered by Dr. Morton at the Massachusetts general hospital in Boston to a patient upon whom an operation was performed by Dr. J. C. Warren. (See Anesthetics.) The action of ether is very similar to that of chloroform. It is possible to produce death by asphyxia with an overwhelming amount and reckless use of ether, although even this is not easy; but it is difficult if not impossible to find a single instance of death which can fairly be attributed to the effects of the drug when used in a moderately careful manner. This is in marked contrast with the results obtained from the inhalation of chloroform, a fact at last acknowledged by many of those who have heretofore employed the latter.

The deaths from chloroform, which experience shows to occur even with the most careful administration, and which appear to depend upon a rapidly developed paralysis of the respiratory centres in the medulla oblongata or upon sudden paralysis of the heart, do not happen with ether. The best and simplest method of administering ether by inhalation is to pour it upon a sponge or towel, and then apply the latter over the mouth and nose. At first the sponge should be held a few inches from the mouth so as to allow a free mixture of atmospheric air; as soon as the patient gets over the primary sensation of choking or suffocation, fresh ether may be added and carried close to and over, but not on, the mouth and nose. Ether is so inflammable that a light should not be brought near to it. The inhalation may be kept up with safety for hours if necessary. Ether may be used externally to produce cooling by its rapid evaporation. If applied in the form of a spray, by means of an "atomizer," the skin may be frozen so that small surgical operations may be performed without pain.

For this purpose, however, it has been nearly superseded by a light coal oil of low boiling point, called rhigolene. - Several of the ethers exist in fruits, giving them their peculiar flavors; and the alcoholic liquors distilled from these fruits retain these principles in combination with some acid. Thus oenanthic ether combined with oenanthic acid forms the oil which contains the fragrance of brandy and some other spirits.