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lo the bishops and presbyters, standing round the table, to washtheir hands. Then the deacon cried out aloud, “ Mutually em-brace and kiss each other;” which being done, the whole con-gregation prayed tor the universal peace and welfare of the church,for the tranquillity and repose of the world, for the prosperity ofthe age, for wholesome weather, and for all ranks and degrees ofmen. After this followed mutual salutations of the minister andpeople ; and then the bishop or presbyter having sanctilied theelements by a solemn benediction, he brake the bread, and deli-vered it to the deacon, who distributed it to communicants, andafter that the cup. Their sacramental wine was usually dilutedor mixed with water. During the administration, they sang hymnsand psalms ; and having concluded with prayer and thanksgiving,the people saluted each other with ;. kiss of peace.

EUCIllT/E, or EUCHITES , [Eax‘v«i, Gr. from pray-er,] a sect of ancient heretics, who were first formed into a reli-gious body towards the end of the 4th century, though their chiefdoctrines and discipline subsisted in Syria, Egypt , and other eas-tern countries, before the birth of Christ. They were thus calledbecause they prayed without ceasing, agreeably to the words otfit. Paul, 1 Thess/v. 17, imagining that prayer alone was sufficientto save them.

Euchjtks, another sect of fanatics, who, in the 1 2th century,infested the Greek and Eastern churches, and who were chargedwith believing a double Trinity, rejecting wedlock, abstainingfrom flesh, treating with contempt the sacraments of baptism andthe Lord’s supper, and the various branches of external worship,and placing the essence of religion solely in external prayer,and maintaining the efficacy of perpetual supplications to the su-preme Being for expelling an evil genius, who dwelt in the breastof every mortal.

EUCHOLOGIUM, °y‘ ov , Gr. i. e. a discourse on pray-er; from rjy>[, praver, and xoyo;, discourse,] the Greek ritual,wherein are prescribed the order and manner of every thing re-lating to the administration of their ceremonies, sacraments, ordi-nations, &c.

EUCLEA, a genus of the dioecia dodecandria class and order.In both male and female the calyx is four or live-toothed ; corollafour or five-parted ; male stamina, twelve to fifteen. In the fe-male, the germ is superior; styles two; berry two-celled. Onespecies, a branching tree of the Cape.

EUCLID of Alexandria, the celebrated mathematician,flourished in the reign of Ptolemy Eagus, about B. C. 280. liereduced all the fundamental principles of pure mathematics, whichhad been delivered down by Thales, Pythagoras, Eudoxus , andother mathematicians before him, into regularity and order, andadded many others of his own discovering; on which account lieis said to be the first who reduced arithmetic and geometry intothe form of a science. He likewise applied himself to the studyof mixed mathematics, and especially to astronomy and optics, inwhich lie also excelled. His works, as we learn from Pappus andProclus , are the Elements of Geomeiry, Data, Introduction toHarmony, Phenomena, Optics, Catoptrics, a Treatise of the Di-vision of Superficies, Loci ad Superficial!, Porisms, Fallacies , andfour books of Conies. Of these the most celebrated is his Ele-ments, of which there have been numberless editions in all lan-guages. A tine edition of all his works now extant was printed in1703, bv David Gregory, Savilian professor of astronomy at Ox-ford. Euclid was greatly esteemed by king Ptolemy ; who onceasking him, if there was any shorter way ot coming at Geometry than by his Elements, Euclid answered, that “ there was no ro\alpath to Geometry.”

Euclid of Mecara, a celebrated philosopher and logician,flourished about B. C. 400. The Athenians having prohibited theMegarians from entering their city on pain of death, this philoso-pher disguised himself in women’s clothes to attend the lecturesof Socrates. After the death of Socrates, Plato and other philoso-phers went to Euclid at Megara, to shelter themselves from thetyrants '.\ho governed Athens. Euclid admitted but one chiefgood ; which he sometimes called God , sometimes Spirit, andsometimes Providence.

EUCOMiS, a genus of the class and order hexandria mono-gynia. Calyx inferior, six-parted, permanent, spreading; fila-ments united at the base into a nectary growing to the corolla.There are four species, plants of the Cape.

EUDIOMETER, an instrument fer ascertaining the purity of

the atmospherical air, or the quantity of oxygenous gas containedin it, chielly by means of its diminution on a mixture with nitrous-acid, or some similar substance. After the composition ot tlie at-mosphere was known to philosophers, it was taken ior granted thatthe proportion of its oxygen varied in different tunes and in differ-ent places; and that upon this variation the purity or noxious qua-lities of air depended. lienee it became ail object ot the greatestimportance to be in possession of a method of determining readilythe quantity of oxygen in a given portion of a.r. Accordingly,various methods were proposed, all ol them depending upon theproperly which bodies pos-ess of absorbing the oxygen, of the airwithout acting upon its azote. 'I hesc bodies were mixed wiili acertain known quantity of almo-phcrie air, in graduated glassvessels inverted over water, and the proportion of oxygen was de-termined by the diminution of bulk. These instruments received(he name of eudiometers, hi cause they were considered as mea-surers of the purity of air ; from *1 tviiu, serenity of the atmosphere,and ri [xi't^ov, a measure. Tin ; eudiometers proposed by differentchemists may be reduced to five. 1. The first eudiometer wasmade in consequence of Dr. Priestley’s discovery, that whennitrous gas is mixed with air over water, the bulk of the mixturediminishes rapidly, ill < onsequemc of the combination of the gaswith the oxygen of the air, and the absorption of the nitric acidthus formed by the water. When nitrons gas is mixed with azoticgas, no diminution at all takes place. When it is mixed withoxygen gas in proper proportions, the absorption is complete.Hence it is evident, that in all ca.-es of a mixture of these twogases, the diminution will lie proportional to the quantity of theoxygen. Of course it w ill indicate the proportion of u\\gm inair; and by mixing it with different portions of air, it will indicatethe different quantities of oxygen which they contain, provided thecomponent parts of air are susceptible of variation. Dr. Priestley’s,method was, to mix together equal hulks of air am! nitrous gas hi alow jar, and then to transfer the mixture into a narrow graduatedglass lube about three feet long, in order to measure the diminutionof bulk. JJe expressed this diminution by the number of hun-dredth parts remaining. Thus, suppose fie had mixed together,equal parts of nitrous gas and air, the sum tot.d ot this mixture was200 (or 2.00): suppose the residuum when measured in the graduated tube to amount to 104 or (1.04), and ol course that Pti partsof the whole had disappeared, lie denoted the purity of the airthus tried by 104. A more convenient instrument was invented by.Dr. Falconer of Bath; and Fontana greatly improved this methodof measuring (lie purity of air. A description of his eudiometerwas published by Ingenliouz, in the first volume of his Experi-ments: it was still farther improved by Mr. Cavendish in 1783;and Humboldt has lately made a very laborious set ol experiments-in order to bring it to a state of complete accuracy. But after allthe exertions of these philosophers, the method ot analysing air bvmeans of nitrous gas is liable to so many anomalies, that it cannotbe depended on. I’rie. tley and Fontana have proved, that theway ot mixing the two airs occasions a great difference in the re-sult, the figure of the vessels is equally important, and so is thewater over which the mixture is made. And even when all thesetilings are the same, the impurity of the nitrous gas may occasionthe most enormous differences in the results. F umboldt hasshewn that the nitrous gas ought to be prepared by means of nitricacid of tlie density 1.170; when a much stronger or weaker acid ■is employed, the gas produced is always i ontaminated with a greatproportion of azotic gas. He has pointed out tlie solution of sul-phate of iron as proper to ascertain the purity ot the nitrous gasemployed, by absorbing the nitrous gas, and leaving the azoticgas or other foreign gases. He has shewn that when nitrons gasof the same degree of purity i-; made to mix very slowly with air,tlie vessel being carefully agitated during ti-.e mixture, the results,provided the experiment i. pertorim-d with address, correspondwith each other. And he has made it piobablc, that when equalquantities of air and nitrous gas, so pure as to contain only about0.1 of azotic gas mixed with it, are agitated together slowly overwater, the diminution divided by 3.S5, gives the quantilv of oxy-gen contained in the air examined. But notwithstanding the in-genuity of his experiments, the anomalies attt nding this method arestill so great as not to render it susieptdih- of accuracy, for thatreason it is umiecessan to give a particular description of thedifferent eudiometers invented to ascertain the purity of air by

means