ETHER, (C2H5)2O, the Aether of pharmacy, a colourless, volatile, highly inflammable liquid, of specific gravity 0.736 at 0°, boiling-point 35° C., and freezing-point −117°.4 C. (K. Olszewski). It has a strong and characteristic odour, and a hot sweetish taste, is soluble in ten parts of water, and in all proportions in alcohol, and dissolves bromine, iodine, and, in small quantities, sulphur and phosphorus, also the volatile oils, most fatty and resinous substances, guncotton, caoutchouc and certain of the vegetable alkaloids. The vapour mixed with oxygen or air is violently explosive. The making of ether by the action of sulphuric acid on alcohol was known in about the 13th century; and later Basil Valentine and Valerius Cordus described its preparation and properties. The name ether appears to have been applied to the drug only since the times of Frobenius, who in 1730 termed it spiritus aethereus or vini vitriolatus. It was considered to be a sulphur compound, hence its name sulphur ether; this idea was proved to be erroneous by Valentine Rose in about 1800. Ether is manufactured by the distillation of 5 parts of 90% alcohol with 9 parts of concentrated sulphuric acid at a temperature of 140°-145° C., a constant stream of alcohol being caused to flow into the mixture during the operation. The distillate is purified by treatment with lime and calcium chloride, and subsequent distillation. The mechanism of this reaction was explained by A. Williamson in 1850. For other methods of preparation see Ethers. 
The presence of so small a quantity as 1% of alcohol may be detected in ether by the colour imparted to it by aniline violet; if water or acetic acid be present, the ether must be shaken with anhydrous potassium carbonate before the application of the test. When heated with zinc dust, it yields ethylene and water. Chromic acid oxidizes it to acetic acid and ozone oxidizes it to ethyl peroxide. In contact with hydriodic acid gas at 0° C., it forms ethyl iodide (R.D. Silva, Ber., 1875, 8, p. 903), and with water and a little sulphuric acid at 180° C., it yields alcohol (E. Erlenmeyer, Zeit. f. chemie, 1868, p. 343). It forms crystalline compounds with bromine and with many metallic salts.
Medicine. - For the anaesthetic properties of ether see Anaesthesia. Applied externally, ether evaporates very rapidly, producing such intense cold as to cause marked local anaesthesia. For this purpose it is best applied as a fine spray, but ethyl chloride is generally found more efficient and produces less subsequent discomfort. It aids the absorption of fats and may be used with cod liver oil when the latter is administered by the skin. If it be rubbed in or evaporation be prevented, it acts, like alcohol and chloroform, as an irritant. Ten to twenty minims of ether, subcutaneously injected, constitute perhaps the most rapid and powerful cardiac stimulant known, and are often employed for this purpose in cases of syncope under anaesthesia. Taken internally, ether acts in many respects similarly to alcohol and chloroform, but its stimulant action on the heart is much more marked, being exerted both reflexly from the stomach and directly after its rapid absorption. Ether is thus the type of a rapidly diffusible stimulant. It is also useful in relieving the paroxysms of asthma. The dose for repeated administration is from 10 to 30 minims and for a single administration up to a drachm.
Chronic Poisoning. - A dose of a little more than a drachm (a teaspoonful) will produce a condition of inebriation lasting for one-half to one hour, but the dose must soon be greatly increased. The after-effects are, if anything, rather pleasant, and the habit of ether drinking is certainly not so injurious as alcoholism. The principal symptoms symptons of chronic ether-drinking are a weakening of the activity of the special senses, and notably sight and hearing, a lowering of the intelligence and a degree of general paresis (partial paralysis) of motion.
 See also J. v. Liebig, Ann. Chem. Pharm., 1837, 23, p. 39; 1839, 30, p. 129; E. Mitscherlich, Pogg. Ann., 1836, 31, p. 273; 1841, 53, p. 95; A.W. Williamson, Phil. Mag., 1850 (3), 37, p. 350.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)