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sien. Essential character: corolla inferior, six-parted, permanent, spreading; filaments united at the base into a nectary growing to the corolla. There are four species, all natives of the Cape.

EUDIOMETRY. The measurement of the quantity of oxygen contained in atmopheric air, or indeed in any gas in which it is not intimately combined, is named eudiometry, and the instrument by which it is performed, the eudiometer. To attain such a measurement, it is merely necessary to present to atmospheric air, some substance which combines with its oxygen, and which either does not afford any gaseous product, or affords one that is easily abstracted and measured. Different substances have been applied to this purpose.

The fluid originally employed by Scheele, in the analysis of the air, the solution of sulphuret of potash, or what is rather more convenient, the sulphuret of lime, is perhaps superior in accuracy to any, at least if the air be not too long exposed to it, and be not in too small quantity proportioned to the quantity of fluid. Phosphorus is applied by a very simple apparatus, but by its solubility in nitrogen gas, it adds to the bulk of the residual air, for which a correction must be made. Nitrous gas was employed by Priestley, it exhibits the result immediately, but is liable to several sources of fallacy. Hydrogen gas was employed by Volta: a given measure of it being put along with a quantity of the air, designed to be submitted to trial, into a graduated tube, and inflamed by the electric spark, the diminution of volume indicating the quantity of oxygen; 100 measures of oxygen require rather less than 200 measures of hydrogen for saturation; about 40 measures of hydrogen are therefore sufficient to saturate the oxygen contained in 100 measures of atmospheric air, but it is proper to use an excess of hydrogen, as otherwise part of the oxygen is liable to escape combination. From 60 of hydrogen, with 100 of atmospheric air, Mr. Dalton states, that the residuum after explosion is 100, 21 of oxygen combining with 39 of hydrogen. The method is simple and expeditious, and as Humboldt and Gay Lussac have remarked, has the great advantage, from the bulk of the mixture, and the great diminution of volume, from the consumption of a given quantity of oxygen, of being more delicate than any other. It also requires no corrections for variations of temperature or atmospheric pressure; and any impurity in the

hydrogen gas, which it has been supposed might be a source of error, may be avoided by care. It affords also the best method of determining the purity of oxygen gas, or the proportion of oxygen in any mixed gas containing it. Humboldt and Gay Lussac, in an elaborate memoir, have pointed out all the circumstances to be attended to in employing it as an eudiometer. (Journal de Physique, t. lx. p. 129.)

From the practice of eudiometry, it was at one time expected, as the name implies, that we should be able to ascertain the purity of the air, with regard to its salutary or noxious power on life. It was soon found, however, particularly by Priestley, (and the fact has also since been established by De Marti), that the air of places the most offensive and unhealthy, afforded as much oxygen as that of others of an opposite description; the air, for example, of crowded cities, of low, damp situations, or of crowded manufactories, has not been found less pure than that of the country; the noxious quality of the air depending not so much on any deficiency of oxygen, as on the presence of effluvia not discoverable by this


It was at one time imagined, that the composition of atmospheric air is not uniform, but that it varies both at different parts of the earth's surface, and still more at different heights. Ingenhouz made a number of experiments to prove the former fact, from which he concluded, that the air is purer, or contains more oxygen at sea than on land, and that in the neighbourhood of marshy situations it contains less oxygen than the standard. (Philosophical Transactions, vol. lxx. p. 354).

Saussure made some experiments on the air at some of the elevated parts of the Alps, the summit of the great St. Bernard, the Buet, &c.; in this air the proportion of oxygen was less than in the air on the plains. (Voyages, t. ii. p. 357 ; t. iv. p. 451.)

Von Humboldt relates also, that air brought from a great height in the atmosphere, by a person who had ascended in a balloon, contained in 100 parts 25.9 of oxygen, while air at the surface contained 27.6; and that at the summit of the Peak of Teneriffe, the proportion of oxygen amounted only to 19, while at the foot of the mountain it was 27. The proportions which he states prove sufficiently the error of the eudiometrical method he employed, and the eudiometer he did use, that with nitrous gas, corrected by trying its purity with sul


phate of iron, is indeed the one which is most liable to fallacy. The analysis of the air in the upper regions of the atmosphere, has since been executed with accuracy by Gay Lussac, assisted by Thenard. A glass balloon was filled with air, at the height of 21,735 feet from the surface, the greatest which has yet been reached, and when opened under water by Gay Lussac after his descent, one half of its capacity was filled by the water, a sufficient proof that it had been accurately closed. The air was subjected to trial, both by Volta's eudiometer, and by the solution of sulphuret of potash; it afforded by the former method 21.49 of oxygen, in 100; by the latter 21.63. Atmospheric air at the surface, analysed at the same time in the eudiometer of Volta, gave precisely the same result, 21.49. (Nicholson's Journal, vol. x. p. 286).

Saussure, junior, also found, that the air on the summit of the Col-du-Geant contained within one-hundredth part as much oxygen as that on the plain, and even this difference may be ascribed to the difficulty of making the experiment with perfect accuracy. The uniformity of the composition of the atmosphere at different parts of the earth's surface, appears also to be established.

Mr. Cavendish originally observed, that air subjected to examination at different times, and air likewise from different places, was of perfectly similar composition; (Philosophical Transactions, vol. lxxiii. p. 129) and the same observation had been made by Fontana, from his own experiments. (Philosophical Transactions, vol. lxix.)

Mr. Davy states, that no sensible difference was found in the air sent from the coast of Guinea, and the air in England. (Journal of the Royal Institution, vol. i. p. 48).

Berthollet found, that the air in Egypt and in France was similar, affording 22 of oxygen in the 100, any difference observed not amounting to a two-hundredth part of the air submitted to trial. (Memoirs relative to Egypt, p. 326).

De Marti, by experiments in Spain, obtained the same uniformity of composition between 21 and 20 of oxygen in the hundred parts) in the air at places at a distance from each other; and he adds also, as established by his experiments, that in every state of the atmosphere, whether with regard to temperature, to pressure, as indicated by the barometer, to winds, to humidity, to the season of the year, or the hour of the

day or night, the results were precisely the same. (Journal de Physique, t. iii. p. 173). And more lately the researches of Humboldt and Gay Lussac, made with the view of determining this question, have establishthe same conclusion. (Journal de Physique, t. lx. p. 152).

The instruments for subjecting atmospheric air to such changes as may indicate its proportion of oxygen, have been called eudiometers. When a mixture of nitrous gas is to be made with atmospheric air, the most convenient apparatus consists in a glass tube closed at top, and graduated by a diamond into cubic inches and parts. The lower aperture may be widened, in order that the gases may more easily be passed up, and likewise to afford the facility of its standing alone upon the pneumatic shelf. It is likewise usual and advantageous to fit a stopper in the mouth by grinding; a cubic inch measure will be required for determining the quantities poured up. A bottle will do for this purpose, and the instrument may be made very well by a chemist who is obliged to work for himself; by taking any small bottle whatever, and pouring its contents of water, by successive times, into the tube placed mouth upwards. By this means he will obtain a graduation, which, whether of the cubic inch or not, will answer the purposes of eudiometry.

When air is to be exposed to a liquid sulphuret, which absorbs the oxygen, the eudiometric tube may be immersed in the liquid. Professor Hope, of Edinburgh, has contrived a very simple, elegant, and accurate apparatus for this purpose, announced in "Nicholson's Journal," iv. 210. It consists of a small bottle, of the contents of about three ounces, intended to contain the eudiometric liquid; into the neck a tube is accurately fitted by grinding, which holds precisely a cubic inch, and is divided into a hundred equal parts, and on one side the bottle, near its bottom, there is a neck into which a stopper is ground in the usual manner. In the use of this apparatus, the bot. tle is first filled with the liquid employed, which is best prepared by boiling a mixture of quick lime and sulphur with water, filtering the solution, and agitating it for some time in a bottle half filled with common air, The tube, filled with the gas under examination, or with common air, if that be the subject of the experiment, is next put into its place, and, on inverting the instrument, the gas ascends into the bottle, where it is brought extensively into contact with the

liquid, by brisk agitation. An absorption of oxygen, if present, ensues, and to supply its place, the stopper in the side of the bottle is opened under water, a quantity of which rushes into the bottle; the stopper is then replaced under water, the agitation renewed, and these operations are alternately performed, till no farther diminution takes place; the tube is then withdrawn, while the neck of the bottle is under water, and after the tube has been kept in this situation for a few minutes, the quantity of the diminution will be seen by the graduated scale upon the tube.

Tubes fitted up for exploding a mixture of hydrogen, or other inflammable gases, with oxygen gas, have been called the eudiometers of Volta; they are usually made very strong, and are provided with two wires, which pass through sockets cemented in holes drilled through the glass, near the top, which is not perforated. The electric spark being passed between these wires, gives fire to the gases, not without some risk of blowing out the confining liquid, or breaking the glass.

EVEN number, in arithmetic, that which can be divided into two equal parts: such are 4, 10, 40, &c. A number is said to be evenly even, when being even itself, it is measured by an even one, an even number of times: such is 32, as being measured by the even number 8, an even number of times 4. Evenly odd number is, that which an even number doth measure by an odd one: such is 30, which 2 or 6, both even numbers, do measure by 15 or 5, odd ones. EVERGREEN, in gardening, a species of perennials which continue their verdure, leaves, &c. all the year: such are hollies, phillyria's, laurustinus's, bays, pines, firs, cedars of Lebanon, &c.

EVERLASTING pea, the name of a perennial plant of the vetch kind, which grows naturally in some places, is easily cultivated, annually yields plenty of excellent provender, and may be cultivated to advantage as green food for cattle, on almost any strong soil.

EVES droppers, or EAVES droppers, persons who listen under walls or windows, or the eaves of a house, by night or day, to hear news, and to carry them to others to cause strife among neighbours; and who may be presented at the leet, or bound to their good behaviour, and punished by stat. Westminster, 1. c. 33.

EUGENIA, in botany, so named in honour of Prince Eugene of Savoy, a genus


of the Icosandria Monogynia class and order. Natural order of Hesperideæ. Myrti, Jussieu. Essential character: calyx fourparted, superior; petals four; drupe oneseeded, four-cornered. There are eleven species. These are trees or shrubs, all natives of the East or West Indies. The flowers are borne on peduncles, proceeding either from the axils or ends of the branches, singly or many together, in a trichotomous structure.

EVIDENCE, in law, proof by testimony of witnesses on oath, or by writings, or records adduced before a court, or magistrate of competent jurisdiction. It is two-fold, either written or verbal; the former by records, deeds, bonds, or other written documents, the latter by witnesses examined viva voce, and called technically, parole evidence. It is also either absolute or presumptive; and may be that which is given in proof by the parties, or which the jury know of themselves, for every thing which makes a fact or thing evident to them, is called evidence.

courts, is very comprehensive and refined. The system of evidence adopted in our The first rule is, that the affirmative of the issue, or matter brought in question by the proceedings, shall be proved; for a negative, generally speaking, cannot be proved, at least, without such circuity, as renders it almost impossible. Where a man is charged required to do, however, this requires some with not doing an act, which by law he is exception, but even then, some evidence is given to prove it. No evidence not relating to the issue, or in some manner connected with it, can be received; nor can the character of either party, unless put in issue by the very proceeding itself, be called in question. The most general and fundamental principle is, that the best evidence the nature of the cause will admit shall be produced; for if better evidence might have been adduced, its being withheld furnishes a suspicion adverse to the party in whose power it was to produce it. So that of a written contract in the custody of the party, no parole evidence can be received as to its contents. But if a deed be burnt, or destroyed by accident, upon positive proof of that fact, other evidence may be given of its contents, and it need not be produced.

Witnesses are summoned by writ of subKing, and 10l. to the party, by statute pœna, to attend on penalty of 100l. to the 5 Eliz. c. 9. besides damages sustained by

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their non-attendance, All witnesses of all religions, who believe in a future state of rewards and punishments are received, but not persons infamous in law by their crimes, nor persons directly interested in the mat ter in issue; and no counsel or attorney shall be compelled to disclose the secrets intrusted to him by his client, but he may give evidence of facts which he knew by other means than for the purpose of the cause. One witness is sufficient to any fact, except in high treason, when by statutes 1 Edw. VI. c. 12, and 5, and 6 Edw. VI. c. 11, two are required, but that is only in treasons of conspiracy against the state, and not treasons relating to the coin, &c. The oath of the witness is to speak the truth; the whole truth, and nothing but the truth, and all evidence is to be given in open court.

The general rules of evidence are, 1. The best evidence must be given that the nature of the thing is capable of. 2. No person interested in the question can be a witness, but to this there are exceptions, as first, in criminal prosecutions; secondly, for general usage, for convenience of trade, as a servant to prove the delivery of goods, though it tends to clear himself of neglect. 3. Where the witness acquires the interest by his own act, after the party who calls him has a right to his evidence. The third rule is, that hearsay of a matter of fact is no evidence; but of matter of reputation, such as a custom, it is in some sort evidence. 4. Where a general character is the matter in issue, particular facts may be received in evidence, but not where it occurs incidentally. 5. In every issue the affirmative is to be proved. 6. No evidence need be given of what is agreed, or not denied upon the pleadings.

In criminal cases the same rules prevail, but evidence of the confessions of the party should be received with caution, and are rejected when obtained through promises or threats. Presumptive evidence should be admitted with cantion, and two excellent rules are given by Sir Matthew Hale, that no one should be convicted of stealing goods of a person actually unknown, unless there is proof of a felony actually committed; and none tried for murder, until the murdered body be found.

Written evidence has been divided into two classes: the one, that which is public, the other private; and this first, has been subdivided into matters of record, and others of an inferior nature. The memo

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rials of the legislature, such as acts of parliament, and other proceedings of the two houses, where acting in a legislative character; and judgment of the King's superior courts of justice, are denominated records, and are so respected by the law, that no evidence whatsoever can be received in contradiction of them; but these are not permitted to be removed from place to place to serve a private purpose, and are therefore proved by copies of them, which in the absence of the original, is the next best evidence.

A bill in Chancery has been admitted as slight evidence against the complainant ; and an answer, is evidence against the defendant in equity himself, though not against others, and the whole may be read by the adverse party. Depositions in Chancery, may be evidence at law, but not against others, and regularly not if the witness be alive, except when taken in perpetuam rei memoriam, &c. Matter in law ought not to be given in evidence upon a trial, but only of fact.

Of persons competent to give evidence. The King cannot be a witness under his sign manual, and a peer must be sworn to give evidence. A judge, or juror may give evidence, the one going off the bench, and the other stating his evidence in open court. Members of corporations cannot be heard in a cause for the corporation. In actions against churchwardens, &c. for money misspent, in indictments for repair of roads, and penal actions for the benefit of the parish, parishioners may be witnesses. Kinsmen are not to be objected to. Husband and wife are not received as witnesses for or against each other, and the bail cannot be a witness for his principal, on account of his direct interest in the event. One that has any benefit under a will, or deed, must release it before he can prove it as a witness, and by stat. 25 Geo. II. c. 6, any devise to a person who is witness to a will, or codicil, is void, and he shall be received as a witness. A bare trustee, it is said, may prove a deed made to himself. In actions for penalties on usury, the bor rower, after he has paid the money, may be a witness to prove it, and in actions against the hundred, &c. the party is received as a witness in his own cause. Persons not of sound memory, attainted of præmunire or conspiracy, convicted of felony, perjury, or other infamous crimes, are incompetent to be received as witnesses, but these are restored to competency by the King's par

don, and the witness shall not be asked any question to accuse himself, but it must be proved by producing the conviction; but upon conviction of perjury, under stat. 5 Eliz. c. 9, nothing but a reversal of judgment can restore a man to competency.

Wills of land must be attested and subscribed in the presence of the testator by three witnesses. In general, the courts are inclined to favour the receiving of evidence, and to consider objections as to interest, to go more to the credibility of the witness than to his competency.

A conviction of treason, of felony, and every species of infamous crime, as perjury, conspiracy, barratry, &c. prevent a man, when convicted of them, from being examined in a court of justice. When a man is convicted of any of the offences before mentioned, and judgment entered up, he is for ever after incompetent to give evidence, unless the stigma be removed, which, in case of a conviction of perjury, on the stat. of 5 Eliz. c. 9, can never be by any means short of a reversal of the judgment, for the statute has in this case made his incompe tency part of his punishment; but if a man be convicted of perjury, or any other of fence at the common law, and the King pardons him in particular, or grants a general pardon to all such convicts, this restores him to his credit, and the judgment no longer forms an objection to his testimony; but an actual pardon must be shewn under the great seal, the warrant for it under the King's sign manual not being sufficient to found this objection to the testimony of a witness, the party who intends to make it, should be prepared with a copy of the judgment regularly entered upon the verdict of conviction, for until such judgment be entered, the witness is not deprived of his legal privileges.

On the question, how far persons who have been defrauded of securities, or injured by a perjury or other crime, can be witnesses in prosecuting for those offences, the event of which might possibly exonerate them from the obligation they are charged to have entered into, or restore to them money which they have been obliged to pay; the general principle now established is this, the question in a criminal prosecu. tion on personal act being the same with that in a civil cause, in which the witnesses are interested, goes generally to the credit, unless the judgment in the prosecution where they are witnesses, can be given in evidence in this cause wherein they are in

terested. But though this is the general rule, an exception to it seems to be established in the case of forgery; for many cases have been decided, that a person whose hand writing has been forged to an instrument, whereby if good he would be charged with a sum of money, or one who has paid money in consequence of such forgery, cannot be a witness on the indictment.

When a witness is not liable to any legal objection, he is first examined by the counsel for the party on whose behalf he comes to give evidence, which is called his examination in chief, who is not to put what are called leading questions, viz. to form them in such a way as would instruct the witnesses in the answers he is to give. He is then cross-examined by the other side, when leading questions are necessarily put; and then he is re-examined as to what he has been asked in his cross-examination.

The party examined must depose those facts only of which he has an immediate knowledge and recollection; he may refresh his memory with notes taken by himself at the time, and if he can then speak positively as to his recollection, it is sufficient; but if he have no recollection further than finding the entry in his book, the book itself must be produced. Deeds, receipts, and writings requiring stamps, must be stamped before they can be received in evidence.

Parole evidence shall not be admitted to annul or substantially vary a written instrument, nor to explain the meaning of a testator in a will, though where there are two persons of the same name; and it is doubtful which is the devisee from an imperfect description, it must be proved by witnesses which is the devisee. By the statute of frauds several things must be evidenced by writing, which previously might be proved by parole only. See FRAUDS.

The general rules has been for the last century under the ablest judges, that no man shall be asked a question, the answer to which might subject him to criminal punishment or pecuniary penalty. It has been lately attempted by some judges to extend it further, to prevent any question being asked which may degrade a man's character, which it is feared will deprive the parties of all the substantial benefits of cross-examination. By stat. 47 Geo. III. made on the spur of a particular occasion, and to serve a party purpose on the trial of Lord Melville, a witness cannot object to

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