Part 155

=Ether, Muriatic (Heavy).= _Syn._ ÆTHER MURIATICUS PONDEROSUS, L. _Prep._ Alcohol, of 80 to 85%, is saturated, in the cold, with chlorine gas, water is next added, and the oily fluid that separates collected and washed with water, as long as any of it is dissolved.

_Prop., &c._ Heavy muriatic ether is a volatile, oily, colourless liquid, boiling at about 245° Fahr., and heavier than water. Its precise constitution is undetermined. This ether enters into the composition of the SPIRITUS MURIATICO-ETHEREUS, a remedy occasionally used on the Continent.

=Ethyl, Nitrate of.= C_{2}H_{5}NO_{3}. _Syn._ NITRIC ETHER, NITRATE OF OXIDE OF ETHYL; ÆTHER NITRICUS, L.

_Prep._ Nitric acid (sp. gr. about 1·375), 50 parts; nitrate of urea, a little (say 2 or 3 parts); dissolve, add alcohol, 50 parts, and distil with the usual precautions, until 7-8ths of the whole (of the liquid portion) have passed over; agitate the distillate with a little water to separate the ether, and preserve the heavier portion.

_Prop., &c._ Nitric ether possesses an agreeable sweetish taste and odour; it is insoluble in water; the alcoholic (but not the aqueous) solution of potassa decomposes it rapidly; sp. gr. 1·112. Its vapour is very apt to explode when strongly heated, and therefore a small quantity only should be prepared at a time.

=Ethyl, Nitrite.= C_{2}H_{5}NO_{2}. _Syn._ NITRIC ETHER, HYPONITROUS ETHER, NITRITE OF ETHER, NITRITE OF OXIDE OF ETHYL, HYPONITRITE OF E.; ÆTHER NITROSUS, Æ. HYPONITROSUS, L. This is a compound, of which 'sweet spirit of nitre' is an impure alcoholic solution.

_Prep._ 1. Starch (potato farina), 1 part; nitric acid (sp. gr. 1·30), 10 parts; mix in a capacious retort, connected with a wide tube, 2 or 3 feet long, bent at right angles, and terminating near the bottom of a two-necked bottle, containing a mixture of alcohol (of 85%), 2 parts, and water, 1 part, and surrounded with a freezing mixture, pounded ice, or very cold water; the other neck of the bottle being connected by a long glass tube with a good refrigerator or condenser. All elevation of temperature must be avoided. The heat of a water bath only must be cautiously applied to the retort. The gas liberated passes into the alcohol, causing the ether to distil in a gentle stream. The tube connecting the retort and bottle must be cooled by means of rag or moist paper, kept wetted with ice-cold water; as, if the temperature of the tube and the alcohol rises only a little, the latter becomes spontaneously hot, and boils violently, by which the product is vitiated. This process is very productive and economical, and yields pure nitrous ether.

2. A mixture of oil of vitriol, 8 parts, and alcohol, 9 parts, is poured upon crystallised nitrate of ammonia, 11 parts, contained in any suitable distillatory vessel connected with a well-cooled receiver. Nitrous ether gradually distils over on the application of a gentle heat. An admirable process, but more expensive than the preceding. Even a common fire may be employed without danger, as the liberation of the ether proceeds gradually, and not almost instantaneously, as in operating in the usual way. Sulphate of ammonia is left in the retort. The product is scarcely inferior to that of the last formula.

3. Rectified spirit, 46 fl. oz.; pure nitric acid (sp. gr. 1·500), 7 fl. oz.; put 15 fl. oz. of the spirit, with a little clean sand, into a quart matrass, fitted with a cork, and a safety tube reaching to within an inch of the spirit, and a second tube leading to a refrigeratory. Fill the safety tube with pure nitric acid, then add through it, gradually and cautiously, 3-1/2 fl. oz. of the acid. When the violent action that ensues is nearly over, gradually add the remaining portion of the acid, 1/2 fl. oz. at a time, and at intervals. Agitate the ether that distils over, first with a little milk of lime, till it ceases to redden litmus paper, and then with half its volume of concentrated solution of chloride of calcium. The pure hyponitrous ether thus obtained should have a density of ·899.

4. (Mr John Williams.) Nitrite of ethyl is best made by passing nitrous acid gas into alcohol.

The nitrous acid gas is prepared by acting upon such bodies as starch, copper, mercury, or arsenious acid with nitric acid. The alcohol is generally recommended in the text-books to be diluted with half its bulk of water; this, however, I consider a decided mistake. The alcohol should be as concentrated as possible, even absolute alcohol is preferable. The main points to be attended to are that the current of nitrous acid gas should be slow and steady, so as to give time for the reaction to proceed properly, and that the vessel containing the alcohol should be kept as cool as possible; in this way much of the production of bye-products will be avoided, and the gas can be passed through the alcohol, as long as it continues to be absorbed.

The resulting liquid is anything but pure; it contains much nitrite of ethyl, some aldehyde, acid--it is even stated to contain malic acid. In fact it is well known that the reaction between the nitrous acid, and such products as alcohol, however pure, is not sharp, but is always accompanied by secondary products.

From the crude alcoholic solution obtained by the method I have described, the pure nitrite of ethyl can be obtained without difficulty. Nitrite of ethyl is an extremely volatile liquid; it boils at about 61° F., whereas aldehyde boils at 90° F., and alcohol at 180° F. Taking advantage of this fact, we are enabled to separate it from the crude liquid by distillation. Some precautions are, however, necessary, to ensure the purity of the product. The flask containing the crude product is placed in a water bath, and connected by bent tubes with several other flasks and bottles. The first tube should be passed into a small empty flask, this will condense most of the alcohol which may pass over during the operation. Then a second bent tube passes into a second flask containing a little water; this condenses any alcohol which may not have been stopped in the first flask, together with free acid, and nearly all the aldehyde.

From this wash bottle a third tube proceeds into a somewhat shallow flask, containing a strong solution of caustic potash; the gas, however, is not allowed to pass through this alkaline liquid, but simply over the surface. In this way the last portion of the aldehyde is absorbed, and the potash solution gradually assumes an amber colour. From this vessel, the gas (for such at the ordinary temperature of the laboratory, the nitrite of ethyl is--in very cold weather it would be necessary to gently warm the different flasks) is passed through a tube charged with anhydrous chloride of calcium to absorb moisture, and the pure and dry nitrite of ethyl thus produced, finally passes into alcohol, which readily absorbs it.

It is only necessary to note the weight of the alcohol used for absorbing the gas, and its weight at the end of the operation, to know the strength or per-centage of nitrite of ethyl which must be in solution. Thus, if 9 oz. of alcohol becomes 10 oz., it is evident we have a solution of 10 per cent.; if it becomes 12 oz., then the strength must be 25 per cent., and so on. Ordinary spirits will answer for condensing the nitrite of ethyl, but it is better to use absolute alcohol, as it is very desirable to avoid the presence of water in any form. The solutions made with weaker spirit soon turn acid; those made with absolute alcohol, on the other hand, keep a long time. It is very true the very strong solutions of 50 and 25 per cent. show traces of acidity when tested with moistened litmus paper, but the 10 per cent. solution is quite neutral.[283]

[Footnote 283: The object of Mr Williams' paper, which is published in the 'Pharmaceutical Journal' for Dec. 8th, 1877, is to give instructions for the preparation of a pure nitrite of ethyl, which when mixed with alcohol in definite proportions, shall supersede the variable compound sold under the name of "Sweet Spirits of Nitre."]

One point I have not mentioned; it is that the distillation must be conducted at the very lowest possible temperature; in fact, the water in the water-bath should only be kept gently warm, and the process should be continued only so long as the conducting tubes feel cool to the touch; when they become warm the distillation should be discontinued. By passing the gas into a tube in a freezing mixture, instead of into alcohol, the pure nitrite of ethyl is readily obtained in a liquid form; it is, however, necessary to seal the tube, otherwise the very volatile liquid would soon be lost.

_Prop., &c._ Pure nitrous ether has a pale-yellow colour, an agreeable odour of apples, and boils at 62° Fahr.; sp. gr. ·947 at 60° Fahr. Commercial nitrous ether contains aldehyde, boils at 70° Fahr., has a more or less suffocating odour combined with that of the pure ether, has a sp. gr. of ·886 at 40° Fahr., and turns brown when mixed with alcoholic solution of potassa, while the latter remains unaltered. It also acidifies by age, whilst pure nitrous ether remains neutral. They are both very inflammable, and burn with a white flame. Ordinary nitrous ether dissolves in about 48 parts of water, and mixes in all proportions with alcohol and sulphuric ether.

Nitrous ether is refrigerant, diaphoretic, and diuretic, but is seldom employed alone, though, when largely diluted with alcohol (sweet spirits of nitric, spirit of nitric ether), it is a common remedy in several diseases. It is also used to flavour malt spirit, in imitation of brandy (British brandy), although for this purpose it is vastly inferior to acetic ether. See SPIRITS (Medicinal).

=Ethyl, [OE]nanthate of.= _Syn._ [OE]NANTHIC ETHER, PELARGONIC ETHER, [OE]NANTHATE OF OXIDE OF ETHYL. _Prep._ 1. The oil obtained towards the end of the distillation of fermented liquors, especially wines, consists, in a great measure, of the crude ether. It is purified by agitation with a weak solution of carbonate of potassa, freed from water by a few fragments of chloride of calcium, and then re-distilled.

_Prop., &c._ [OE]nanthic ether is colourless; lighter than water; boils at about 500° Fahr.; and has a powerful, intoxicating vinous odour, resembling that of an empty wine cask or bottle that has been exposed to the air for some time. It is very sparingly soluble in water, but freely soluble in alcohol. Its sp. gr. is ·862. As obtained by distillation, it is united with a little [OE]NANTHIC ACID. 2200 imperial gallons of wine (about 35 hogsheads) only yielded 2-1/5 lbs. of the mixed oil.

=Ethyl, Oxalate of.= (C_{2}H_{5})_{2}C_{2}O_{4}. _Syn._ OXALIC ETHER, OXALATE OF OXIDE OF ETHYL; ÆTHER OXALICUS, L. _Prep._ Alcohol and dry oxalic acid, equal parts, are digested together in a glass flask furnished with a very long glass tube of small bore, so that the spirit, volatilised by the heat, may be condensed, and flow back into the flask. After 6 or 8 hours the process is generally complete, and the liquid contains merely a trace of free acid, from which it may be separated.

_Prop., &c._ A colourless, oily liquid, slightly heavier than water, boiling at 363° Fahr., only slightly soluble in water, and having an aromatic smell. Alkalies decompose it. Sp. gr. 1·09.

=Ethyl, Sulphate of.= (C_{2}H_{5})_{2}SO_{4}.

_Prep._ The vapour of pure anhydrous sulphuric acid is passed (with the usual precautions) into perfectly anhydrous ether; the resulting syrupy liquid is agitated with a mixture of 4 volumes of water, and 1 volume of ether, and after repose the upper stratum, which is an ethereal solution of the sulphate of ethyl, is decanted, and the oxide of ethyl volatilised by a very gentle heat. The colourless liquid forming the residuum is the true sulphuric ether or sulphate of ethyl just referred to. It is a very unstable compound, and cannot be distilled without suffering decomposition.

=Ethyl, Valerianate of.= C_{2}H_{5}C_{5}H_{9}O_{2}. _Syn._ VALERIANIC ETHER, VALERATE OF OXIDE OF ETHYL; ÆTHER VALERIANICUS, L. _Prep._ By passing dry hydrochloric acid gas into an alcoholic solution of valeric acid. It is a fragrant, volatile liquid, lighter than water, having a high boiling-point, and a rich fruity odour, said to closely resemble that of butyric ether or pine-apple oil. It is used to flavour liqueurs, &c.

=ETHYL'AMINE.= NH_{2}(C_{2}H_{5}). _Syn._ ETHYL-AMMONIA. One of the bases of the ethyl-series, obtained by substituting one atom of hydrogen in ammonia NH_{3} by ethyl C_{2}H_{5}.

=EUCALYP'TIN.= A peculiar substance existing in Botany Bay kino. A substance exuded by several species of the _Eucalyptus_. It has been employed medicinally in diarrh[oe]a.

=EUCALYPTOL.= See EUCALYPTUS.

=EUCALYPTUS.= The _Eucalypti_, of which there are many species, belong to the natural order _Myrtaceæ_, and are natives of Australia, where they are known under the names of "gum-trees," or as "stringy-bark trees." The most interesting and important characteristic of these plants is the power they undoubtedly possess of correcting, if not of removing, the pestilential exhalations which are regarded as the origin of the fevers that occur in marshy localities. This discovery is due to M. Ramel, and was made by him in 1856.

M. Gimbert, amongst other cases, cites one of a farm, twenty miles from Algiers, the atmosphere surrounding which was of a very pestilential character. In the spring of 1867 13,000 eucalyptus trees were planted on the farm, and M. Gimbert states that since then not a single case of fever has taken place, the freedom from disease occurring the same year the plants were placed in the ground, and the good effects commencing whilst the trees were only two or three mètres in height.

The following is extracted from 'Les Mondes' (1876):--"Between Nice and Monaco there is a locality so unhealthy that the Paris, Lyons, and Mediterranean Railway Company have been obliged to change every two or three months the watchman at a crossing there.

"Plantations of the eucalyptus have been formed there, and at present the same watchman has resided there for several months with his family without experiencing the least inconvenience."

Again:--"In the Campagna, about three miles from Rome, there stand some deserted church buildings and a monastery, the latter having been abandoned because of the mortality amongst the monks caused by the noxious exhalations. Some six years since a company of French trappists, having obtained permission from the Italian Government, planted the grounds in and around the monastery with eucalyptus trees, and the result is stated to have been so total an immunity of the building from fever, although situated in the worst part of the Campagna, that the monastery is now tenanted, the health of the occupants being, it is said, unimpaired."

The writer in the 'Pharmaceutical Journal,' who contributes this statement, adds:--"Whether this grand result has been obtained through the efficacy of the extract of the eucalyptus taken each morning with their cup of black coffee, or whether it is to be attributed to the effects of the plantations, I leave to scientific men to determine."[284]

[Footnote 284: Bentley.]

It seems very probable that the effects above described are due to the eucalyptus having such extensive and far-spreading roots, which suck up and appropriate the moisture of the surrounding soil, the presence of which, aided by heat, giving rise to vegetable decomposition, is believed to be the cause of malarial poisoning.

The avidity of the plant for water is very great; it has been computed that one tree will absorb ten times its weight of moisture from the soil.[285] It is most likely owing, at any rate in very large measure, to this cause, rather than to the supposed antiseptic and disinfecting odours exhaled by its leaves, that the salubrious effects of the eucalyptus are due. The blue gum tree, or _Eucalyptus globulus_ (so distinguished because of the rounded form of the lid which covers its unexpanded flower bud), has been successfully introduced into Asia, Africa, and Southern Europe. If, as asserted, it can only exist in a climate where the temperature is never lower than the freezing point, its domestication (save in hot-houses) is impossible in our own country.

[Footnote 285: 'Pharm. Journal,' February 5th, 1876.]

The _Eucalyptus globulus_ is a very rapidly-growing tree, and attains to great proportions. "In some cases it has been known to attain the colossal dimensions of 350 feet in height and a 100 in circumference."[286]

[Footnote 286: Bentley.]

This magnitude is entirely out of proportion to the size of the seed, which is very minute; so minute that it has been computed one pound weight of the seed could produce 162,000 trees. Various preparations of the leaves and bark of the eucalypti have been introduced into medicine, which will be found under the respective pharmaceutical preparations. They were asserted to be specially serviceable in intermittent fevers and bronchitis. The idea that their efficacy in the former class of disease was due to the presence in the barks of the eucalypti of an alkaloid similar to, if not the same as, quinine, has been shown to be an erroneous one, from the experiments of the Government chemist of Ootacamund (Mr Broughton), who, after a most careful chemical analysis, failed to discover either quinine, quinidine, cinchonine, cinchonidine, or the least trace of any one of the cinchona alkaloids.

When the leaves of the _Eucalyptus globulus_ are held to the light they reveal the presence of little semi-transparent dots, which are found to be receptacles for a volatile oil, that may be obtained in large quantity by submitting the plant to aqueous distillation.

This volatile oil has been examined by Cloez, who found it to consist chiefly of a substance allied in chemical characters to camphor, which substance he named _eucalyptol_.[287] Any therapeutic power possessed by the eucalyptus may be referred to this substance, since, as just stated, it cannot be due to a bark alkaloid.

[Footnote 287: Messrs Faust and Homeyer state that Cloez's "Eucalyptol" is a mixture of terpen and cymol.]

Before finishing our notice of the reputed curative effects of the eucalyptus we may mention that Dr Gimbert employs the leaves instead of lint for dressing wounds and fetid ulcers, and says he has found them, when thus used, excellent deodorisers; that another method of employing the leaves of the eucalyptus consists in having them made into cigarettes, which are reported to be useful in asthma and bronchial complaints. Lastly, let us state that another species of eucalyptus exudes a very astringent substance, which, from its appearance and properties, being so analogous to kino, has been denominated _Botany Bay kino_. (See EUCALYPTIN.)

The essential oil of eucalyptus, which, according to the species of the plant from which it is obtained, varies in colour from light yellow to light blue, is now largely employed as a diluent for the more delicate volatile oils used in perfumery.

Many species of the eucalyptus yield excellent timber, possessed of great hardness and durability, and little affected by moisture. This timber has the power of resisting the attacks of insects. The wood of the eucalyptus is also very rich in potash. The maple and the elm, which are regarded as yielding a large per-centage of this substance, afford only about half as much as can be obtained from the eucalyptus, this latter tree yielding 21 per cent. of potash.

The barks of different species have also been advantageously utilised for paper making, as well as for tanning.

In this country eucalyptus seeds are reared in a greenhouse. They may be sown in a mixture of loam, peat, and ordinary soil, with a sprinkling of sand on the surface.

The following directions for the cultivation of the eucalyptus in England were communicated to the 'Medical Times and Gazette' of 1873 by Mr Bennett Stanford, of Pyt House, Tisbury:--"I have successfully reared from seed two dozen of these trees, and they are now growing well out of doors. I obtained the seed five years ago from South Australia, and forced it in a hothouse; in one year it was four feet high, and now, in its fifth year, it is growing rapidly in a sheltered position in the park, having attained a height of thirty feet. The first three years the tree must be taken under cover in the winter, and the fourth and fifth years should be protected for several feet up with wisps of hay or straw. When the trees are kept indoors in winter it should be in an orangery or very high greenhouse, with plenty of light and a little water."

=EUCHLO''RINE.= A bright-yellow gas, prepared by gently heating chlorate of potassa with hydrochloric acid. It is probably a mixture of chlorous acid and free chlorine. Prof. Stone, of Manchester, has found Euchlorine of a great service as an aerial disinfectant.

=EUGLENÆ.= These are ciliated infusorial animalcules inhabiting ponds and water-tanks. Sometimes they abound in water in quantities so enormous as to impart to that fluid a blood-red appearance. The principal species are the _Euglena viridis_ and the _Euglena pyrum_. Their presence is supposed to indicate the existence in the water in which they are found, of decaying animal and vegetable matter upon which they are believed to feed.

=EUPHOR'BIUM.= _Syn._ GUM EUPHORBIUM; EUPHORBIUM (Ph. E.), L. The concrete resinous juice of the _Euphorbia canariensis_, and other species of the same genus. It is a powerful acrid, purgative, rubefacient, sternutatory, and vesicant, and the violence of its action has led to its disuse.

=EU'PIONE.= An ethereal liquid forming the chief portion of the light oil of wood-tar, and which also exists in the tar obtained during the destructive distillation of animal substances, and in the fluid product of the distillation of rape oil. It is separated from these substances by agitating them with oil of vitriol, or a mixture of oil of vitriol and nitre, and subsequent cautious distillation. Pure eupione is tasteless, exceedingly thin, limpid, and aromatic; boils at 116° Fahr.; and is the lightest fluid known; sp. gr. ·655. It is very inflammable, burns with a very bright flame, and gives a transient greasy stain to paper. It is isomeric with hydride of amyl. Other volatile hydrocarbons of like origin are often confounded with eupione by chemical writers.

=EUPYR'ION.= Any contrivance for obtaining instantaneous light; as a lucifer match, &c.

=EVAC'UANTS.= _Syn._ EVACUANTIA, L. Medicines which augment the secretions or excretions. CATHARTICS, DIAPHORETICS, DIURETICS, EMETICS, ERRHINES, EXPECTORANTS, and SIALOGOGUES, belong to this class.

=EVAPORA'TION.= The conversion of a fluid into vapour by means of heat, diminished atmospheric pressure, or exposure to a dry atmosphere. Evaporation is had recourse to--1. For the vapour as a source of heat or power, as in the case of steam-boilers, &c.;--2. To separate volatile fluids from impurities or other bodies, which are either fixed or less volatile;--3. To recover solid bodies from their solutions, as in the preparation of extracts, chemical salts, &c.;--4. To concentrate or strengthen a solution by the expulsion of some of the fluid matter that forms the menstruum;--5. To purify liquids by the dissipation of the volatile matters which may contaminate them.