Cooley's Cyclopaedia of Practical Receipts Volume I Part 218

According to the beautiful theory of Liebig, ethyl is a 'salt-basyle,'

forming 'haloid salts' with chlorine, iodine, and bromine; its oxide is ether, and the hydrate of this oxide alcohol. The compound ethers may be compared with ordinary salts in which the metal is replaced by the radical ethyl.

=Ethyl, Oxide of.= (C_{2}H_{5})_{2}O. _Syn._ ETHER, SULPHURIC ETHER, aeTHER (B. P.), aeTHER SULPHURICUS (PH. E. D. & U. S.), ae. RECTIFICATUS, ae.

VITRIOLICUS, ae. SPIRITUS VITRIOLI DULOIS, L. A colourless, highly volatile, fragrant, inflammable liquid, obtained by distilling a mixture of sulphuric acid and alcohol. It was not known before the 13th century.

_Prep._ There are two methods employed for the preparation of ether. The one is by mixing the whole of the ingredients at once, and immediately subjecting them to distillation at a proper temperature; the other is by adding the alcohol in a slender streamlet to the acid, previously heated to the etherifying point. The former, though less economical, is the one more generally employed.

1. Rectified spirit, 3 lbs.; sulphuric acid, 2 lbs.; carbonate of pota.s.sa (previously ignited), 1 oz.; pour 2 lbs. of the spirit into a gla.s.s retort, add the acid, and place the vessel on a sand bath, so that the liquor may boil as quickly as possible, and the ether, as it forms, pa.s.s over into a well-cooled receiver; continue the distillation until a heavier fluid begins to pa.s.s over, then lower the heat, add the remainder of the spirit, and distil as before; mix the distilled liquors together, pour off the supernatant portion, add the carbonate of pota.s.sa, and agitate occasionally for one hour; finally, distil the ether from a large retort, and keep it in a well-stoppered bottle. Sp. gr. 750.

2. The strongest oil of vitriol, 3 parts, are mixed with alcohol, q. s.

(about 2 parts at 830) to reduce its sp. gr. to 1780; an object which may be easily obtained by distilling off some of the ether if required.

The still or retort is then connected with a vessel full of alcohol, of at least 90%, by means of a small syphon tube, furnished with a stop-c.o.c.k; the longer limb of which should be of gla.s.s, and so arranged that it just dips into the mixture of acid and alcohol. Heat is next applied, and the contents of the still raised to the boiling-point as rapidly as possible, and as soon as full ebullition commences the stop-c.o.c.k of the syphon is cautiously turned, so as to allow the alcohol to flow down in such a manner as to keep the boiling liquid exactly at the same level; or, in other words, to supply a quant.i.ty of alcohol exactly equal to that of the liquid which distils over. By careful manipulation the whole of the alcohol which enters the retort pa.s.ses over as ether and water, and this decomposition proceeds for some time, and would continue for an unlimited period did not the sulphuric acid ultimately become too weak to form ether, from the gradual absorption of the superfluous water contained in the alcohol. Were it convenient or practicable to use absolute alcohol, a given weight of sulphuric acid of the proper strength, would maintain the power of producing ether for an indefinite period. In practice, the quant.i.ty of alcohol that may thus be etherified is twice or thrice as much as by the common process, while neither sulphurous acid, sulphovinic acid, nor sweet oil of wine is generated, and the residual liquid of the distillation continues limpid, and has only a pale-brown colour. This is termed the 'continuous,' or 'Boullay's' method. (This process is similar to that given in the B. P.)

3. Alcohol of 90%, five parts are mixed with oil of vitriol, 9 parts, in a vessel of copper or iron immersed in cold water; the mixture is next introduced into a still or retort, and raised to a state of ebullition as rapidly as possible, as before. A fresh quant.i.ty of alcohol, equal in bulk to the liquid distilled over, is then added to the liquid in the still, and distillation again had recourse to. As much concentrated alcoholic solution of pota.s.sa as will give it a perceptible alkaline reaction is next added to distilled liquor, which is then rectified by the heat of a water bath, as long as the ether which distils over has the sp. gr. 720 to 725 at 80 Fahr. Instead of the pota.s.sa, a little milk of lime may be used, along with its own bulk of water. By allowing the product to stand for some days over chloride of calcium or quicklime, and again rectifying it along with one of these substances, perfectly pure ether may be obtained.

_Obs._ The mixture of alcohol with sulphuric acid requires some caution.

It is best done by introducing the alcohol into a suitable vessel, and imparting to it a rapid whirling motion, by which a considerable conical cavity is formed in the centre, and into which the acid may be gradually poured with perfect safety. The mixed fluids should be brought to a state of rapid ebullition, as quickly as possible, as without this precaution much of the alcohol distils over before the liquor acquires the proper temperature for etherification. On the small scale, a tubulated retort, connected with a Liebig's condensing tube, and two globular receivers surrounded with a freezing mixture, or ice-cold water, may be employed as the distillatory apparatus. The second receiver should be connected with the first one by means of a bent gla.s.s tube, reaching nearly to the bottom of the former; and the whole of the joints should be securely luted, as soon as the expanded air has been allowed to escape. We have employed the following convenient little apparatus for the preparation of small quant.i.ties of ether, and it will be found very suitable for the distillation of most other highly volatile liquids, and particularly for boiling mixtures of alcohol and organic acids. By connecting the neck of a flask or digester containing volatile fluids with the lower instead of the upper end of the refrigerator, ebullition may be carried on without loss, as the vapour will be condensed, and run back into the vessel from which it has distilled.

[Ill.u.s.tration:

_a._ Condenser tube.

_b, c_ Gla.s.s tube.

_d._ Funnel by which cold water runs in from the water bottle _h_.

_e._ Pipe by which water escapes through _f_ into the bottle _g_.

_i._ Retort.

_k._ Adapter, connecting the retort with the condenser.

_l._ Adapter, connecting the condenser with the bottles _t, t_.

_A._ Wooden tressel, with movable arms _n, o_, for supporting and adjusting the heights of the condenser.

_B._ Wooden stool for supporting the water bottle.

_q._ Furnace.

_r._ Support for the furnace.

_p._ Gutter for carrying off water that overflows the funnel _d_, and preventing its escape along the pipe _c_.

_s._ Leg of syphon connected with bottle containing alcohol.

_t, t._ Gla.s.s globes, placed in the basins _v, v_, and surrounded with pounded ice or ice-cold water.

_w._ Safety tube, containing a little mercury at _x_.]

For the rectification of ether, a water bath is employed along with the above simple refrigerator, and the receivers surrounded by ice or a freezing mixture.

_Chem. comp., &c._ Ether is generally regarded as the oxide of ethyl, and alcohol as the hydrate of this base. This view is borne out by a.n.a.lysis, which proves that ether differs from alcohol by the elements of water.

Recent experiments have also shown that the relation existing between the two compounds is--if alcohol be expressed by the formula C_{2}H_{6}O, the true formula of ether will be (C_{2}H_{5})_{2}O. We cannot describe these experiments here, but we may remark that ether cannot be made to combine with water directly, nor can alcohol be converted into ether by the abstraction of water, pure and simple, without the aid of other substances.

The compound ethers may be compared to ordinary salts in which the metal is replaced by a radical termed ethyl, having the formula C_{2}H_{5}. This view is, of course, in accordance with the theory which regards ether as the oxide of ethyl.

According to theory, 1 equivalent, or 46 parts of absolute alcohol, should produce 1 eq., or 37 parts, of pure ether; but in practice, the greatest product obtained by operating according to Boullay's method, which produces more ether than any other, does not exceed 33-1/2 parts for the preceding quant.i.ty of alcohol, or 715%. A mixture of 9 parts of oil of vitriol, and 5 parts of alcohol of 90%, ceases to produce ether after 31 parts of such alcohol have been added.

The most economical method of etherification is that known as the continuous ether process, or the process of Boullay. When this is adopted, the retort or flask should be fitted with a sound cork, perforated by an aperture to receive a thermometer, and the application of the heat, and the flow of alcohol, should be so managed, that a temperature of 300 Fahr. and a state of rapid and violent ebullition (points of essential importance) are maintained.

_Prop., Uses, &c._ Pure ether is a colourless, transparent, and very limpid fluid, having a penetrating and agreeable smell, and a burning, sweetish taste; its evaporation produces the sensation of extreme cold; when prevented, a sensation of heat is experienced. Its specific gravity varies between 712 and 724. If it contains water it begins to crystallise in brilliant white plates when cooled to -24 Fahr., and become a white crystalline ma.s.s at -46 or -47 Fahr.; but if absolutely pure, ether cannot be solidified by any degree of cold that can be produced, it remaining fluid when placed in contact with solid carbonic acid, at a temperature of about -148 Fahr. Boils at 96 or 97 Fahr.; is very combustible; is soluble in about 10 parts of distilled water, and mixes with alcohol in all proportions. It abstracts corrosive sublimate, terchloride of gold, sesquichloride of iron, and many of the alkaloids, from their watery solutions, and is hence invaluable in a.n.a.lysis and pharmacy. It readily dissolves the volatile and fixed oils, and most fatty matters, as well as sulphur and phosphorus in small quant.i.ties. By exposure to light and air it absorbs oxygen, and water and acetic acid are gradually formed. It is decomposed by exposure to a high temperature. Its evaporation occasions intense cold. The greatest degree of cold yet produced (-166 Fahr.) has resulted from the admixture of ether with solid carbonic acid. Ether is powerfully stimulant, narcotic, and antispasmodic, and externally refrigerant, if allowed to evaporate, or stimulant and counter-irritant if its evaporation is prevented, and is used in various diseases. Applied to the forehead by means of the fingers or a strip of linen, it generally relieves simple cases of nervous headache. In _pharmacy_ it is largely employed in the preparations of tinctures alkaloids, spirits, &c.; and in _chemistry_ is invaluable in organic a.n.a.lyses. Its princ.i.p.al commercial application is as a solvent for pyroxyline, in the manufacture of collodion. It is also employed as a solvent of resins, india rubber, &c., in the preparation of varnishes, and for several other useful purposes.--_Dose_, 20 drops to 2 fl. dr.; in water or wine. Excessive doses of ether produce intoxication resembling that from alcohol, and require similar antidotes. Sulphuric ether is said to be taken largely in the north of Ireland as a stimulant, particularly in Antrim. Shortly before the discovery of chloroform, it was found that when the vapour of ether was inhaled it gradually produced insensibility to pain. It was therefore employed as an anaesthetic in surgical operations. Having been found less efficient than chloroform, and more troublesome to administer, its use for this purpose has been abandoned.

_Tests._ Ether may be recognised by its volatility, odour, taste, sparing solubility in water, admixture with alcohol in all proportions, great inflammability (burning with a yellowish-white flame), and its power of dissolving fats and resins. Its further identification can only be effected by ultimate a.n.a.lysis.

_Pur._ The ether of the shops generally contains alcohol, water, or acetic acid, and sometimes all of them. Its usual specific gravity fluctuates between 733 and 765. Exposed to the air, it volatises entirely. It turns litmus paper red; sometimes very slightly, and occasionally even not at all. 1/2 fl. oz. mixes completely with 1/2 pint of water. Pure ether should, however, be neutral to test-paper, although seldom so. When shaken in a minim measure with half its volume of concentrated solution of chloride of calcium, its volume should not lessen. 10 fluid ounces of water should only dissolve 1 fluid ounce of ether, and remain transparent.

[Ill.u.s.tration]

_Preserv._ Ether rapidly evaporates at common temperatures when kept in corked bottles, and even in bottles secured with ground-gla.s.s stoppers and tightly tied over with bladder and leather; it also becomes sour by age.

To prevent this waste, the stoppers should fit accurately, and the bottles should be placed in as cool a situation as possible. Bottles furnished with ground-gla.s.s caps, as well as stoppers, are frequently employed. (See _engr._) Dewar's 'ether phial' is formed on a similar principle. We have seen bottles of ether accurately stoppered, tied over with bladder, and thickly coated with wax, which have yet become quite empty by a voyage to the tropics, though they still appeared to be as closely secured as when they were first filled.

_Caution._ The vapour of ether is very inflammable, and when mixed with atmospheric air, it forms a violently explosive mixture. The density of this vapour is 2586, that of air being 1; hence it rapidly sinks, and frequently acc.u.mulates in the lower parts of buildings, especially cellars which are badly ventilated, in the same way as water does. The only remedy is thorough ventilation. Many serious accidents have arisen from this cause, for no sooner is a light carried into an apartment where such vapour is present than an explosion takes place.

=Ethyl, Acetate of.= C_{2}H_{5}C_{2}H_{3}O_{2} _Syn._ ACETATE OF OXIDE OF ETHYL, ACETIC ETHER, PYROLIGNEOUS ETHER; aeTHER ACETICUS, L. A compound discovered by the Count de Lauraguais in 1759.

_Prep._ 1. Acetate of pota.s.sa, 3 parts (or an equiv. quant. of acetate of soda), alcohol (85%), 3 parts, oil of vitriol (strongest), 2 parts, are mixed together and distilled, by the heat of a sand bath, from a gla.s.s or earthenware retort into a well-cooled receiver; the distillate is agitated with a little water to remove undecomposed alcohol, and then digested first with a little chalk to remove acidity, and afterwards with fused chloride of calcium, to absorb water; it is, lastly, rectified by a gentle heat.

2. Rectified spirit (sp. gr. 84), 50 parts, acetic acid (sp. gr. 1075), 33 parts, are mixed together, and oil of vitriol (strongest), 10 parts, added; the distillation is continued until 65 parts have pa.s.sed over, and the distillate, after digestion for some hours on a little dry carbonate of pota.s.sium, is rectified as before, the first 50 parts only being kept for use.

_Prop., &c._ Acetic ether is colourless, and bears a considerable resemblance to ordinary ether, but it has a much more agreeable and refreshing odour. It boils at 165 Fahr.; has a sp. gr. of 89 at 60 Fahr., dissolves in about 7 parts of water; and mixes in all proportions with alcohol and ether. It is decomposed by alkalies and the strong acids.

Acetic ether is diaph.o.r.etic, stimulant, antispasmodic, and narcotic.--_Dose_, 1/2 to 2 fl. dr.; in similar cases to those in which sulphuric ether is employed, and especially in nervous and putrid fevers, spasmodic vomitings, and diseases of the bowels and stomach, arising from debility, and not of an inflammatory character. Its princ.i.p.al consumption is in the manufacture of British brandy.

=Ethyl, Benzoate of.= C_{2}H_{5}C_{7}H_{5}O_{2}. _Syn._ BENZOIC ETHER, BENZOATE OF ETHER, B. OF OXIDE OF ETHYL; aeTHER BENZOICUS, L. _Prep._ Alcohol (sp. gr. 830), 4 parts; benzoic acid (cryst.), 2 parts; concentrated hydrochloric acid, 1 part, are distilled together; as soon as the product turns milky when mixed with water, the receiver is changed, and the liquid that distills over collected; to this liquid water is added, and the supernatant ether is decanted, and boiled with water, and a little oxide of lead (to separate benzoic acid); it is, lastly, freed from water by allowing it to stand over chloride of calcium.

_Prop., &c._ A colourless oily liquid, slightly heavier than water, and possessing an aromatic odour and taste. It boils at 410 Fahr., and is miscible with alcohol and ether.

=Ethyl, Bromide of.= C_{2}H_{5}Br. _Syn._ aeTHER HYDROBROMICUS, L. A volatile, ethereal liquid, discovered by Serullas.

_Prep._ Bromine, 8 parts; alcohol, 32 parts; dissolve, place the mixture in a retort, add of phosphorus, 1 part, and distil by a gentle heat as soon as the liquid becomes cold. The ether is separated from the distillate by the addition of water.

_Prop., &c._ A very volatile liquid, with a penetrating taste and smell; boiling at 105 Fahr., and heavier than water.

=Ethyl, Bu'tyrate of.= C_{2}H_{5}C_{4}H_{7}O_{2}. _Syn._ BUTYRIC ETHER, PINE-APPLE OIL; aeTHER BUTYRICUS, L. _Prep._ By pa.s.sing hydrochloric acid gas into an alcoholic solution of butyric acid, and purifying the product from free acid.

Commercially, from crude butyric acid saponified with caustic pota.s.sa or baryta, and the resulting soap distilled along with alcohol and oil of vitriol.

_Uses._ Crude butyric ether forms the 'pine-apple oil' of commerce, and when largely diluted with rectified spirit, the 'pine-apple essence' so much employed as a flavouring substance by confectioners, liqueuristes, &c. It imparts a delicious flavour to sweetmeats, rum, arrack, punch, &c.

The Germans add it to common rum, to form the flavouring for their 'pine-apple ale.'

=Ethyl, Carbonate of.= (C_{2}H_{5})_{2}CO_{3}. _Syn._ CARBONIC ETHER, CARBONATE OF OXIDE OF ETHYL; aeTHER CARBONICUS, L. _Prep._ Fragments of pota.s.sium are added to oxalic ether, gently warmed, as long as bubbles of gas are formed; the excess of metal is removed from the semi-solid ma.s.s, some water added, and the whole distilled. The carbonic ether floats on the surface of the liquid in the receiver, and is collected, dried by contact with chloride of calcium, and rectified along with some pota.s.sium or sodium, till it ceases to yield acetate of pota.s.sa when acted on by caustic pota.s.sa.

_Prop., &c._ Colourless, limpid, and aromatic; tastes pungent and burning; boils at 259 to 260 Fahr. It greatly resembles oxalic ether. It is decomposed by alkalies.

=Ethyl, Chlo'ride of.= C_{2}H_{5}Cl. _Syn._ LIGHT HYDROCHLORIC E., CHLORIDE OF ETHYL; aeTHER HYDROCHLORICUS, L. A highly volatile compound, formed of ethyl and chlorine.

_Prep._ Rectified spirit of wine is saturated with dry hydrochloric acid gas in the cold, and the product is distilled in a retort connected with a Wolfe's apparatus, the first bottle of which should be two thirds filled with tepid water (70 to 75 Fahr.), and the remainder surrounded with a mixture of ice and salt. To render it perfectly anhydrous, it must be digested on a few fragments of fused chloride of calcium.

A mixture of oil of vitriol, 3 parts, and alcohol, 2 parts, is poured upon common salt (dried), 4 parts; and the whole distilled as before.

_Prop., &c._ This ether has a sweetish taste; is soluble in about 15 parts of water, and miscible in all proportions with alcohol; boils at 54 Fahr.; burns with a flame edged with green; is neutral to test paper; and does not affect a solution of nitrate of silver. Sp. gr. 921, at 32 Fahr.--_Dose_, 10 to 30 drops, as an antispasmodic and a powerful diffusible stimulant. Owing to its extreme volatility it can only be taken dissolved in spirit.