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fixed right of future enjoyment. An estate is contingent when a right of enjoyment is to accrue on an event which is uncertain. III. With respect to the number of owners, estates in all the above three respects may be held by one or amongst many in four ways, in severalty, in joint tenancy, in coparcenary, or in common. Severalty is the holding lands, &c. as the single owner thereof, which is generally implied where nothing more is said; as to the rest, see JOINT TENANTS and PARCENERS. As to the title to estates, see TITLE; and as to TENURE, see that article.

ESTATES are acquired by different ways, as by descent from a father to son, which is distinguished from purchase, conveyance or grant from one to another, by deed or by will; and a fee-simple is the largest possible estate, and by the words, all his estates, in a deed or will, every thing passes which the party has, and therefore this word creates, in a will or estate in fee, without a limitation to the heirs.

ESTATES are divided into real, such as lands, which descend to the heir, and personal, as chattels, which go to the execu


ESTOPPEL, in law, an impediment or bar of action, arising from a man's own act; or where he is forbidden to speak against his own deed; for by his act or acceptance he may be estopped to speak the truth. There are three kinds of estoppels, viz. by matter of record, as by letters patent, fine, recovery, pleading, taking of continuance, confession, imparlance, warrant of attorney, admittance. By matter in writing, deed, &c. or by matter in pais, i. e. by some act, such as livery, entry, partition, acceptance of rent, or of an estate. Thus if a man seised in fee takes a lease of his own land, by this he is estopped, or prevented, from claiming the fee during the term.

ESTOVERS, in law, signifies any kind of allowance out of lands; but in general it is a liberty of taking necessary wood for the use or furniture of a house or farm, and this any tenant may take from off the land let or demised to him, without waiting for any leave, assignment, or appointment of the lessor, unless restrained by special covenant to the contrary.

ESTRAYS and WAIFS. Estrays are any valuable beasts, not wild, found within a lordship whose owner is not known; such as are commonly impounded and not claimed. They are then to be proclaimed in the church and two nearest market towns, on two market-days, and not being claimed by

the owner, belong to the King, and now commonly by grant of the crown, to the lord of the manor, or the liberty. Beasts feræ naturæ, cannot be estrays. Swans, but no other fowl may be estrays. The estray is not the absolute property of the lord till the year and day, with proclamation; and therefore if it escape from the lord before, to another manor, he cannot reclaim it. If proclamation is neglected, the owner may claim it without paying the expences, and may do so at all times within the year and day, upon paying them; but afterwards it is vested in the lord absolutely. The owner may seize it without telling the marks, or proving the property, till the trial; the lord should demand a sum for the keeping it, and the owner may then tender any reasonable sum, the propriety of which, if it is not received, may be ascertained by the jury upon the trial. Amends may be tendered generally without a particular sum, before the lord fixes the amount. An estray must not be used; but a cow may be milked of necessity. The King's cattle cannot be estrays. The year and day runs from the first proclamation, not the seizure,

Waifs are goods which are stolen, and waved, or left by the felon on his being pursued, for fear of being apprehended; and forfeited to the King or lord of the manor; and though waifs are generally spoken of things stolen, yet if a man be pursued with hue and cry as a felon, and he flies and leaves his own goods, these will be forfeited as goods stolen; but they are properly the fugitive's goods, and not forfeited till it be found before the coroner, or otherwise of record, that he fled for the felony.

ESTREAT, in law, extractum, a true copy, or note, of some original writing or record, and especially of fines and amercements, and imposed in the rolls of a court, and extracted or drawn out from thence, and certified into the court of Exchequer, from whence process is awarded to the sheriff to levy them: in order, therefore, to be relieved from any fine or estreat, application is made to that court upon motion.

ESTREPEMENT, in law, estrepamen tum, from estropier mutilare, or extirpare, the spoil made by a tenant for life upon any lands or woods, to the prejudice of the reversioner: also a writ, in two cases; the one, when the person having an action de pending (as a formedon, writ of right, &c.) for recovery of the possession of land without damages, sues to prohibit the tenant

from making waste during the suit; the other lies after possession is adjudged, but not delivered, and to prevent like waste which is expected. The court of Chancery now grants an injunction, on filing a bill and before answer, to prevent waste, and these writs are disused.

ETHER. The action of the more power. ful acids on alcohol, gives rise to an order of compounds of some importance from their peculiar properties. These, as produced by the different acids, vary somewhat in their qualities: they also agree, however, in the possession of certain general properties; they are highly volatile, odorous, pungent, and inflammable, miscible with water, and capable of combining with alcohol, in every proportion. 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 known. 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 fragrant odour are disen. gaged; and the temperature rises to about 180 of Farenheit. 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 temperature is raised to 208, the ether being formed at that temperature and distilling 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 obscured with white fumes, which condense into a matter of apparently an oily consistence.

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 employed in the first distillation, on applying 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 injured, 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 suspended 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 potash being previously added to it, in the proportion of two drachms to each pound; this attracts the sulphurous acid, and renders even the water rather less volatile. Another method of rectification, proposed by Pelletier, ("Memoires de Chimie," tom. i. p. 316.) and revived by Dize, ("Nicholson's Journal," 4to, vol. iii. p. 43,) which Mr. Murray, from whose "System" the present article is extracted, 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 sulphuric; and this, with the water, remains in the retort. Even after either of these processes, the ether may still contain a portion of alcohol, which usually passes over in the first stage of the distillation. This is best abstracted by agitation 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 extremely pure.

A degree of obscurity still prevails with regard to the theory of the formation of sulphuric ether; different views having been entertained of the agency of the acid on the alcohol. The explanation 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 exposed to heat, it was supposed that part of the acid suffered decomposi tion, its oxygen being attracted by the hydrogen of the alcohol, and forming water; the balance of attractions between the principles of the alcohol being thus broken, part of its carbon is precipitated, and is diffused through the liquor, rendering it

thick, and dark coloured; and the remaining quantities of its elements, its carbon, hydrogen, and oxygen, unite and form the ether.

This explanation is founded on the sup: position, that the sulphuric acid is decom, posed in the process by which ether is formed. But a few years ago it was affirmed by Fourcroy and Vauquelin, from a series of experiments which they undertook to elucidate this subject, that such a decomposition of the acid is not at all necessary to its formation: that although it may take place to a certain extent towards the end of the process, when the liquor is loaded with carbon, there is no indication of it in the first stage, during which, principally, the ether is formed; no sulphurous acid gas is discharged, and if the process be stopped at the end of this stage, the remaining acid, they found, is capable of saturating the same quantity of alkali, as before its mixture with the alcohol. (“Nicholson's Journal," 4to, vol. i. p. 385.)

These chemists gave, therefore a different view of this subject, which they applied even to the action of this acid on vegetable matter in general. They suppose that the sulphuric acid suffers no decomposition, and that it acts no other part than causing, by the exertion of a disposing affinity, the decomposition of the alcohol. By this affinity, it disposes part of the hydrogen and of the oxygen of the alcohol to combine and form water: the balance of attractions being thus subverted, a quantity of carbon is separated, and the remaining carbon, hydrogen, and oxygen, combine and form ether.

This theory, however, advanced by these chemists, is not perhaps perfectly established. Though they affirm, that the acid remaining after the formation of ether, saturates as much alkali as it would do previous to its mixture with the alcohol, the experiment by which this is supposed to be established is not altogether without fallacy. During the formation of ether, there is always, also a formation from the elements of the alcohol, of some of the vegetable acids, particularly of the acetous and oxalic. The oxalic, it has been ascertained by the observation of Cadet, is formed copiously even without heat, merely by allowing the mixture of acid and alcohol to remain at rest for some time. These will contribute to the saturation of the alkali; so that if none of the sulphuric acid were decomposed, more alkali ought in reality to be

saturated by it after, than before its mix ture with the alcohol.

There are also some facts which appear to prove the necessity of the presence of some substance that can part with its oxygen, for the production of ether. Thus, ether cannot be formed from the muriatic acid, but it can with facility from the oxymuriatic; it is likewise formed with great rapidity by the nitric acid; neither of which can exert a strong disposing affinity to water, though both very readily part with their oxygen.

Whatever opinion, however, may be formed as to the manner in which the changes that take place during the formation of ether are produced, the nature of the changes themselves seems sufficiently well ascertained. It is proved, that a quantity of the hydrogen of the alcohol is expended in the formation of water, as the remaining acid is always in a diluted state: a still larger quantity of carbon is also separated, and is mechanically diffused through the liquor. The ether, therefore, which is the only other product of the operation, is to be considered as a compound of hydrogen, and carbon, and perhaps oxygen; differing from alcohol, in containing a much larger quantity of hydrogen proportioned to its carbon; and to this predominance of hydrogen its great levity and volatility are owing. This conclusion is confirmed, by its analysis by combustion, the products of which are water and carbonic acid; the former being derived from the combination of its hydrogen with the oxygen of the air, the latter from the same combination of its carbon. Mr. Cruickshank found, that the vapour of ether requires about seven times its volume of oxygen to saturate it in combustion; the products being water and carbonic acid gas, the latter amounting to 4.6 parts by measure. From this result, compared with a similar experiment on alcohol, he inferred, that the proportion of carbon to hydrogen in the ether, is as 5 to 1 nearly, while in alcohol it is as 8 or 9 to 1. ("Nicholson's Journal," 4to, vol. v. p. 205.)

Besides ether, there are some other products formed during the action of sulphuric acid upon alcohol. Towards the end of the process an oily-like matter distils over, which has been named Sweet Oil of Wine. This can be obtained separate, by changing the receiver: it is unctuous, thick, and less volatile than the ether, but is soluble both in it and in alcohol. It is obtained like

wise by distilling sulphuric ether from a fresh quantity of acid. Chemists are not agreed respecting its nature: Fourcroy and Vauquelin consider it as similar to ether, and that it differs from that fluid principally in containing a larger proportion of carbon, which gives to it more density and less volatility. Other chemists, particularly Higgins, have affirmed, that it is a compound of ether and sulphurous acid, and that by the addition of an alkali which combines with the acid, a quantity of ether may be obtained from it. It does not appear, however, that this combination can be formed directly, or that ether can combine with a large quantity of sulphurous acid, so as to assume the properties of oil of wine; and though this substance may contain a portion of this acid, it is not improbable that it also differs from ether in its ultimate composition. At the same time that the oil of wine is disengaged, there is formed a quantity of olefiant gas, which passes off. It was in this process, indeed, that the production of this gas was first observed; and the action of sulphuric acid on alcohol still affords us the best method of obtaining it pure. The same gas is produced, by passing the vapour of ether through an ignited earthen tube; but when a glass tube is used, a different variety of carburetted bydrogen is obtained.

At this stage of the process the liquor becomes so loaded with carbon, and at the same time is capable of bearing so high a temperature, that if the heat is kept up, the sulphuric acid is decomposed, and a large quantity of sulphureous acid gas and carbonic acid is produced. If the greatest care is not taken to keep the heat moderate, the whole liquor is apt to swell suddenly up, and boil over into the receiver. If examined at this time, it is likewise found to contain a portion of acetic and oxalic acids mixed with the sulphuric acid, which is diluted with water, and through which the carbon is diffused. Sulphuric ether, when highly rectified, is the lightest of all known liquids. It is obtained without difficulty of the specific gravity of .732, and by careful distillation has been brought so low as .716. It is colourless, and perfectly transparent; has a strong pungent taste, and a fragrant penetrating smell.

It is likewise the most volatile liquid. It evaporates rapidly, even at the common temperature, and under the common pressure of the atmosphere; so that it cannot be poured from one vessel into another without loss, and any part wet with it immedi

ately becomes dry. In vacuo it boils at a temperature considerably below 32: under the atmospheric pressure it boils at 38. In the spontaneous evaporation of ether a large quantity of caloric is absorbed, so as to produce cold: water inclosed in a small tube may be easily frozen, by ether evapo rating from a piece of muslin wrapt round the external surface of the tube; and Dr. Higgins has observed, that in the rapid evaporation of ether, the temperature in frosty weather falls so low as 40. Ether congeals at 47.

Ether is highly inflammable, and, when kindled, burns with a clear white flame, without any smoke, and without leaving any residuum, the products of its combustion being water and carbonic acid: the residual water generally gives indications too of sulphuric acid, which may either be adventitious, or perhaps is essential to the constitution of this species of ether. From its high inflammability, its vapour diffused in the atmosphere sometimes takes fire; or if a drop or two of ether be added to atmospheric air, or oxygen gas, an explosion happens on the contact of an ignited body.

Sulphuric ether is soluble in water; but only in a limited proportion. When highly rectified, it requires ten parts of water for its solution; and this is a property by which we are enabled to determine its purity, as, if more soluble, it contains either water or alcohol, It is soluble in alcohol in every proportion.

Sulphuric ether exerts no sensible action on the fixed alkalies or earths. It unites with ammonia by distillation,

Neither does it act on the metals; but it is capable of decomposing the saline combinations of those that have a weak affinity to oxygen, by attracting that principle. Thus, muriate of gold dissolved in it is gradually decomposed, and the gold precipitated in its metallic form.

On the simple inflammables its action is somewhat similar to that of alcohol. It dissolves sulphur, as Favre has shewn, one ounce of ether dissolving about 25 grains ; the solution has a strong sulphurous smell and taste: it is less soluble in water than pure ether, and deposits sulphur as the ether volatilizes. ("Nicholson's Journal," vol. xiii. p. 69.) Ether likewise dissolves a small proportion of phosphorus: this solution, like the phosphuretted alcohol, is decomposed by water; but does not, like it, appear luminous during the decomposition.

Sulphuric ether is a solvent of many of

the vegetable proximate principles, as the essential oils, camphor, and resins. It is also, as has already been remarked, the most powerful solvent of caoutchouc.

In medicine it is employed as a diffusible stimulant.

Nitric ether. The action of nitric acid on alcohol is so violent, that the formation of nitric ether is extremely difficult, and requires considerable precaution. One part of the acid may be added gradually to three parts of alcohol without any risk; and after standing for some days, to allow of their reciprocal action, heat may be applied, when a portion of nitric ether that has been formed distils over, with a quantity of unchanged alcohol. A preparation of this kind has been long known in pharmacy, under the name of sweet spirit of nitre. But when the proportion of acid is increased the action becomes very violent; a quantity of aërial fluid is suddenly formed, and disengaged at each addition; and it requires particular arrangements to admit of so much acid being added as is sufficient to convert the whole of the alcohol into ether.

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The method proposed by Navier is, to put into a strong earthenware bottle twelve parts of alcohol, and immerse it in water or ice; eight parts of nitrous acid are to be added in successive portions, mixing them by agitation at each addition; the bottle is well corked, and tied over, and is put in a cool place. At the end of six days the cork is to be perforated, to allow a quantity of gaseous fluid that has been formed, and is retained by compression, to escape. The bottle is then uncorked, the liquid poured into a funnel, and the acid liquor beneath allowed to run off from the ether which swims above.

An ingenious method, somewhat similar, but less hazardous, was employed by Dr. Black. He first poured into a strong flint glass bottle six ounces of alcohol; then, by a funnel, the tube of which reached to the bottom of the bottle, he poured in two ounces of water gently, so that it did not mix with the alcohol, but raised it above it; and, lastly, he poured in four ounces of nitrous acid in the same manner, so that the small column of water was interposed between it and the alcohol. The phial was set aside for some time in a cool place: the water attracted the alcohol at the one surface, the acid at the other, and thus brought them very gradually together, so as to admit of their reciprocal action without violence. At the end of a few months they were com

pletely mixed, and nitric ether formed, which floated above, was withdrawn and rectified by distillation.

The theory of the formation of nitric ether is as obscure as that of sulphuric ether. It is ascertained, however, that even from the commencement of the process the acid is decomposed; nitric oxide gas is disengaged; and Pelletier found that the decomposition was complete, nitric acid not being discoverable, either in the liquor which passed over, or in the residuum.

It is also proved, that in the formation of nitric ether the alcohol suffers decomposition, as in the residual liquor oxalic and acetic acids are formed. There is no deposition, however, of carbonaceous matter, as there is in the formation of sulphurie ether, the residual liquor being quite transparent, and of a light colour. It appears to follow, therefore, from these facts, that in the formation of nitric ether part of the elements of the alcohol combine with oxygen from the nitric acid, and form oxalic and acetic acids; carbonic acid gas too is formed and disengaged, as Pelletier found, in considerable quantity, and much of the nitric acid mixed with nitric oxide and nitrogen gases. (Mémoires de Chimie, tom. i. p. 138.)

It is difficult, however, to determine in what manner these facts are to be combined, so as to give with precision the theory of the formation of nitric ether: nor is it very apparent, whether any of the elements of the nitric acid enter into its composition, or whether they are entirely disengaged during the process. It might be supposed, that it must contain more carbon than sulphuric ether, as none is deposited during its formation; but we are not certain what quantity is carried off in the state of carbonic acid.

Nitric ether has some resemblance in its properties to sulphuric ether. Like it, it is light and volatile, and has been said, when highly rectified, to have these qualities even in a higher degree than sulphuric ether. It is also inflammable, burns with an enlarged flame, and is said to deposit more charcoal. It is soluble in water and in alcohol. Its odour is strong, though scarcely so agree. able as that of sulphuric ether; in the state, however, of what has been named dulcified spirit of nitre, it is more fragrant. Its colour is usually yellow; but this, as well probably as some of its other qualities, appears rather to be owing to the presence of ni

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