ETHER. The action of the more pow erful acids on alcohol gives rise to an or der of compounds, of some importance from their peculiar properties. These, as produced by the different acids, vary somewhat in their qualities : they also a gree, however, in the possession of cer tain general properties; they are highly volatile, odorous, pungent, and inflam mable, miscible with water, and capable of combining with alcohol, in every pro portion. These compounds are named ethers; the specific name of each being derived from the acid, from the action of which on alcohol it has originated, as the sulphuric, nitric, muriatic, or acetic ether.
Sulphuric ether has been longest knovim. The following is the process by which it is prepared Upon a quantity of alcohol in a retort, (selected thin at the bottom. so as to be capable of bearing- a sudden heat,) is poured an equal weight of sulphuric acid, then mixed with the alcohol above by frequent and moderate agitation. From this mixture the alcohol acquires a brownish colour ; vapours having a fra grant odour are disengaged ; and the temperature rises to about 180 of Fah•en heit. When the mixture of the acid and alcohol is complete, the retort is to be immediately placed in a sand bath, and connected with two large receivers, which are kept cool, by water or ice. Heat is to be immediately applied to the retort. The liquor boils when the tem perature is raised to 208, the ether be ing formed at that temperature and dis tilling over : the condensation of it is to be promoted, by keeping the receivers cool with water, and the distillation is to be continued till about half the quantity of alcohol employed has distilled over, or until the neck of the retort becomes ob scured with white fumes, which condense into a matter of apparently an oily consist ence.
The liquor which distils over into the receiver is the sulphuric ether. If, to the residual liquor in the retort, there be added half the quantity of alcohol em ployed in the first distillation, on apply ing heat, a new production of ether will take place ; and this may be repeated for several times.
Towards the end of the distillation, a portion of sulphurous acid is formed and disengaged, with which the ether is so far impregnated, that its fragrance is in jured, and its odour rendered pungent and acrid. A portion of water likewise distils over, by which it is diluted. The
liquor in the retort, at the end of the distillation, is also found diluted with a portion of the water ; it is, however, thick, and of a black colour, from a quantity of carbonaceous matter sus pended in it.
From the water and sulphurous acid the ether is freed, by subjecting it to a second distillation with a very gentle heat applied by a water-bath, pure pot ash being previously added to it, in the proportion of two drachms to each pound ; this attracts the sulphurous acid, and ren ders even the water rather less volatile. Another method of rectification, propos ed by Pelletier, (" Memoires de Chimie," torn. f. p. 316.) and revived by Dize, (" Nicholson's Journal," 4to. vol. iii. p. 43,) which Mr. Murray, from whose " System" the present article is extract ed, found to succeed extremely well, is, to distil the ether of the first distillation from a little black oxide of manganese, the oxygen of which combines with the sulphurous acid, converting it into sul phuric ; and this, with the water, re mains in the retort. Even after either of these processes .the ether may still con tain a portion of alcohol, which usually passes over in the first stage of the dis tillation. This is best abstracted by agi tation with water, which imbibes the alcohol, and a little of the ether ; the greater part of the ether floats above, may be drawn off, and by distilling it with a very gentle heat is obtained ex tremely pure.
A degree of obscurity still prevails 'Iwith regard to the theory of the forma tion of sulphuric ether ; different views having been entertained of the agency of I the acid on the alcohol. The explana tion that was generally given, after the establishment of the theory of Lavoisier, 'was founded on the supposition, that the acid acts principally by communicating oxygen. Alcohol consists of carbon and '.hydrogen, with a portion of oxygen : when mixed with sulphuric acid, and ex posed to heat, it was supposed that part ' of the acid suffered decomposition, its oxygen being attracted by the hydrogen of the alcohol, and fanning water ; the balance of attractions between the prin ciples of the alcohol being thus broken; part of its carbon is Precipitated, arid is diffused through the liquor, rendering it thick and dark coloured ; and the remain ing quantities of its elements, its carbon, hydrogen, and oxygen, unite and form the ether.