Ether

Ether, $(C\_2H\_5)\_2O$, otherwise called ETHYLIC ETHER, VINIC ETHER, and SULPHURIC ETHER, is prepared from alcohol by the action of sulphuric acid at an elevated temperature. Alcohol is placed in a retort or still, and about an equal volume of sulphuric acid is added. Heat is at once developed by the mixing of the liquids, and on raising the temperature ether vapour passes over along with a proportion of alcohol. At the same time a stream of alcohol is allowed to pass into the still, and the heat is so regulated that a constant temperature of about 266° (130° C.) is maintained. When five volumes of alcohol in all have been added, the temperature is allowed to rise to 286° (141° C.), at which point impurities commence to pass over. The ether so obtained contains alcohol, sulphurous acid, and water, and these may be removed by treatment with solution of chloride of calcium, &c., and subsequent redistillation.

The chemical reactions which take place in this process are of great interest, and may be divided into two stages. (1) The sulphuric acid acts on alcohol, forming ethyl-sulphuric acid and water.

Sulphuric Acid. Alcohol. Ethyl-sulphuric Acid. Water.

(2) This acid again is acted on by alcohol, with the re-formation of sulphuric acid and the production of ether.

Ethyl-sulphuric Acid. Alcohol. Ether. Sulphuric Acid.

From this it will be plain that the sulphuric acid is restored again, and is ready to attack alcohol anew, so as to form more ether. This process would go on indefinitely, were it not that the water liberated in the first reaction dilutes the sulphuric acid, and ultimately renders it too weak for further action.

Ether is a colourless, transparent, volatile liquid of great mobility and high refractive power, and possessing a fragrant odour and a fiery, passing to a cooling, taste. It has a specific gravity of .720 at 60° (15.5° C.), and boils at 96° (35.6° C.), forming a vapour more than two and a half times as dense as air. When reduced to a temperature of -24° (-31° C.), ether freezes. It volatilises spontaneously when placed in an unconfined position, as in the palm of the hand, and vaporises so quickly as to produce intense cold. Indeed, when water is covered with ether, and the latter assisted in its evaporation by being blown upon, it escapes so readily as to reduce the temperature of the water to the freezing-point. It is very inflammable, burning with a yellow-white flame; and mixed with air or oxygen, it gives rise to a dangerous explosive mixture, and hence great care requires to be taken in its distillation to keep all lights and fires out of the room where the vapours are condensing. When ether is added to its own bulk of water, briskly agitated, and allowed to settle, the two liquids appear to separate again; but it is found that the ether has taken up one-eighth of its volume of the water, whilst the latter has dissolved the same quantity of ether. It is readily miscible with alcohol in all proportions. Ether is one of the best solvents for the oils and fats, and hence is employed in analysis for the solution and separation of the oils from other organic matters, as in the analysis of oil-cakes, &c. It is also a good solvent of iodine, sulphur, phosphorus, and of strychnine and other alkaloids, as well as of corrosive sublimate and other salts.

Ether enters into combination with many acids, forming compound ethers possessing great fragrance, such as

Euanthic ether, on which the flavour and smell of wines, brandy, &c. so much depend, has been proved to be a mixture of various ethyl ethers, chiefly ethyl caprate.

Ether is useful in the preparation of freezing mixtures, the mixture of ether and solid carbonic acid giving rise to a very low temperature indeed. When inhaled by man and the lower animals, ether first produces stimulating and intoxicating effects (it is sometimes used as an intoxicating beverage), but afterwards it gives rise to drowsiness, accom- panied by complete insensibility, which entitles ether to be regarded as an important anaesthetic agent; and, indeed, for some time it was the only agent used for producing Anaesthesia (q.v.) in operations, but in many places it has been entirely superseded by the employment of chloroform.