Ether

[Fr. éther, from Lat. & ther; Gr. aither. from aitho, to light up, to kindle, to burn or blaze: Sansk atapa, the heat of the sun-root, tap, to make hot.j (Physics.) That which is above the element of fire; the clear upper air; pure refined air; a thin, subtile matter, much finer and rarer than air, which, according to some philosophers, begins from the limits of the atmosphere, and occupies the heavenly space. (Chem.) Ether is used as a generic term to denote a series of organic bodies having the general formula Hn +1(CnHn+1)0. They are looked upon as being derived from corresponding alcohols by the abstraction of one equivalent of water; or, in other words, they are regarded as the oxide of a radical represented by the formula within the brackets, of which their alcohols are the hydrated oxides. This theory has undergone a modification of late years, the followers of Gerhardt laying it down as a principle that the equivalent of an ether when existing alone is double, and that its compounds are formed by substitution. There are strong reasons in support of this theory, as will be seen when we consider the double and compound ethers. Ethers are subdivided into-1. Simple ethers , of which ordinary vinous ether may be taken as a type (C2H2OC2H3); 2, the double ethers, which consist of two equivalents of different ethers united, as the methyl -ethylic ether (C2H2OCH3); and the compound ethers, which contain an equivalent of an ether united to an equivalent of an acid or halogen, and correspond to salts; thus, nitric ether is C2H2O,NO; hydrochloric ether, C2H2Cl. From the formulas given of the double and compound ethers, it will be seen that they may be considered as double atoms of the original ether, in which one atom is replaced by another ether in one case, and by an anhydrous acid or a halogen in the other. In common parlance, ether is generally taken to mean the ordinary sulphuric ether, as it is improperly Fig . 968. termed from being obtained from alcohol by the action of sulphuric acid. Pure ether is an extremely limpid, colorle , transparent fluid, very volatile, and refracting light with great power. Its odor is peculiarly powerful and penetrating if inhaled; at first producing exhilaration, and afterwards stimulating effects, followed by insensibility to pain. As an anæsthetic it is, if not so powerful, at least le dangerous than chloroform. It has a specific gravity of 0-724 at 55° F., and boils at 94-8° F. It is used for producing cold artificially by rapid evaporation. Its vapor is extremely dense, sinking heavily in air; great care should therefore be taken not to pour it out with a flame below it, otherwise an explosion of a dangerous character might ensue. Mixed with certain proportions of air, it forms a highly explosive compound. It di olves readily in alcohol, but very sparingly in water. It is much used in medicine; but its principal commercial application is as a solvent for pyroxylin in the manufacture of collodion. In analysis it is used as a solvent for fats, is prepared from alcohol by the action of sulphuric acid at an elevated temperature. On the small scale, the apparatus which may be employed for the purpose is the retort and receiver ( Fig . 968) into which a mixture of equal weights of spirits of wine, or rectified spirit and oil of vitriol, or, by volume, 2 of alcohol and 1 of sulphuric acid, are placed, and heat being cautiously applied, a liquid distils over, which consists of ether and water. In a short time, the contents of the retort begin to blacken, and the operation must be stopped, or the distillate will become contaminated with sulphurous acid. On the large scale, the proce of Boulay, or the continuous proce , as it is termed, is now generally in use. Equal measures of alcohol and sulphuric acid are heated in a capacious retort, which is connected with a reservoir of alcohol in such a manner that, as fast as the ether distils off, a corresponding amount of alcohol makes up the deficiency. The proce is continued until thirty times the original amount of alcohol is used, the sulphuric acid acting over and over again as the agent by which an equivalent of water is abstracted from an equivalent of alcohol. See SECTION II.