26

gum babul.

ACADEMY.

A gum similar to gum arabic is produced by A. decurrens, A. molissima, (the silver wattle,) and A. affinis, (the black wattle,) in New Holland, and by A. karro at the Cape of Good Hope. Gum Senegal is the produce of A. Verek and A. Adansonii, natives of the western coast of Africa. Yet A. Verek is also said to yield true white gum arabic. Catechu is obtained from the wood of A. catechu. The astringent bark and pods of some species are used for tanning. The bark of A. Arabica is administered in India as a powerful tonic medicine. The locust-tree of North America (Robinia pseud-acacia) is often called A. Other species of Robinia also receive the same name. Acacia (A. flowers) is an old

medical name for sloe flowers.

Acacia.

ical Arts, 15; (3) Swedish Physics and Natural History, 15; (4) Foreign Physics and Natural History, 15; (5) Mathematics, 18; (6) History, Philology, and Fine Arts, 12. The resident members preside in rotation during a term of three months. The Royal A. of Sciences at Copenhagen owes its origin, like the last mentioned, to six learned men, employed by Christian VI., in 1742, to arrange his cabinet of medals. In 1743 the king, on the recommendation of Count Holstein, their first president, took the A. under his protection, liberally endowed it, and ordered that Natural History, Physics, and Mathematics should be embraced within the sphere of its operations, at first limited to the national history and antiquities. The A. of Sciences of Mannheim was founded in 1755 by the Elector-Palatine Karl Theodor, and divided into the sections of History and Physical Science. The A. of Sciences of Munich was founded in 1759. Soon after the erection of Academy, a name originally applied to the philosophical Bavaria into a kingdom it was reorganized on a very extensive school of Plato, and derived from the place in which that phi- footing, under the presidency of Jacobi. The A. of Lisbon, losopher was accustomed to meet and converse with his pupils. established by Queen Maria in 1779, numbers 60 members; This was a garden or grove in the suburbs of Athens said to viz., 24 ordinary, and 36 honorary and foreign, and is divided have once belonged to the hero Academus, and by him to have into three sections: (1) Natural Science; (2) Mathematics; been presented to the citizens for a gymnasium. In its com- (3) Portuguese Literature. The Royal Irish A. dates its origin mon acceptation the word A. is loosely applica to any species from 1782, when a number of gentlemen, chiefly connected of school which professes to communicate more than the mere with the University of Dublin, associated themselves for the elements of instruction. The first institution in ancient times pursuit of Science, History, and Literature. The American that seems to merit the name, in this sense, of A., was the A. of Arts and Sciences was established at Boston in 1780; celebrated Museum, founded at Alexandria in the third c. it had previously existed in another form, the original instituB.C. by Ptolemy Soter, which concentrated in that intellectual tion being due to Franklin. The A. of Sciences at Vienna capital all that was most eminent in science, philosophy, was founded in 1846. It is divided into the sections of Hispoetry, and criticisin. After this model the Jews, and, at a tory and Philology; Mathematics and Natural Science; Philater period, the Arabians, founded numerous institutions for losophy, Political Economy, and Medicine. Among the As. the promotion of learning. During the Middle Ages, with established for the cultivation of particular departments the exception of the Moorish institutions at Granada and of knowledge are the following: (1) Languages.-The Acad Cordova, in which poetry and music formed prominent sub-emia della Crusca, or Academia Furfuratorum, was founded jects of study, we find nothing corresponding to the modern at Florence in 1582, chiefly for the purpose of promoting the idea of an A. save the learned society established in his own purity of the Italian language, The Royal Spanish A. was palace at the suggestion of his teacher, Alcuin, by Charle-founded at Madrid in 1714, by the Duke of Escalona, for the magne. This association was dissolved by the monarch's cultivation and improvement of the national language. A death; and not till the middle of the 15th c., when the con- similar institution was founded at St. Petersburg in 1783, and quest of Constantinople drove many learned Greeks to seek afterward united to the Imperial A. At Stockholm a similar an asylum in Italy, do we find any trace of a similar institu- A. was established in 1786; and at Pesth (for the cultivation tion. After the decline of the Greek and Platonic As. of the Magyar language) in 1830. (2) Archæology.-At the of Florence there arose institutions of a more comprehensive head of the antiquarian institutions stands the Académie des character, the example of which spread from Italy through- Inscriptions, founded at Paris, in 1663, by Colbert. (See INout all the states of Europe. As. may be divided into STITUTE.) For the elucidation of Northern languages and anthose established for general ends and such as contemplate tiquities an A. was founded in 1710 at Upsala, in Sweden; specific objects. The results of their labors in their various and a similar institution was established at Cortona, in Italy, departments of study are reported at the periodic meetings, in 1727. Both have issued valuable works. The A. of Herand printed in the records of the A. Prizes are generally es-culaneum was founded at Naples in 1755, by the Marquis of tablished as the rewards of distinguished merit in original Tanucci, for the elucidation of Herculanean and Pompeian discovery, or for excellence in the treatment of subjects pro- antiquities. An A. especially for the investigation of Tuscan posed for competition. Among general As. deserving of men- antiquities was established at Florence in 1807; and at Paris, tion in the first place is the famous A. of Sciences at Paris, in 1805, a Celtic A. for the elucidation of the language, hisestablished by Colbert in 1666, and now a branch of the In- tory, and antiquities of the Celts. (3) History.-The Royal stitut de France. The first scientific A. founded in modern A. of Portuguese History was founded at Lisbon, in 1720, by times was the Academia Secretorum Naturæ, established at John V. At Madrid, in 1730, a learned association was formed Naples in 1560, and afterward put down by a papal interdict. for the elucidation of Spanish history. A Historical A. has It was succeeded by the A. of the Lincei, founded at Rome existed for some time at Tübingen. (4) Medicine.—The Acadby Prince Ceci, which attained distinguished success. Galileoemia Natura Curiosorum was established at Vienna, in 1652, was one of its members. Subsequently arose the A. del Ci- by the physician Bauschius, for the investigation of remarkamento, at Florence, and the A. degl' Inquieti, of Bologna, ble phenomena in the animal, vegetable, and mineral kingafterward incorporated into the A. della Tracea, and, finally, doms. The Académie de Médecin of Paris was founded in in 1711, merged into the Institute of Bologna, or Clementine 1820, for the prosecution of researches into all matters conA. The Berlin A. of Arts and Sciences, founded in 1700 by nected with the public health, such as epidemics, etc. The Frederick I., was, in 1710, divided into four sections: (1) Phys- Vienna A. of Surgery, established in 1783, is, properly speakics, Medicine, and Chemistry; (2) Mathematics, Astronomy, ing, a college. (5) Fine Arts.-The Academies of Painting and Mechanics; (3) German Language and History; (4) Ori- and Sculpture of St. Petersburg and Paris are institutions for ental Literature, in special connection with missions. The the education of pupils. The French Académie des Beaux first president was Leibnitz, whose extraordinary versatility Arts is a branch of the Institute. The Royal A. of Arts in of genius qualified him for a leading place in all its depart- London was founded in 1768 for the promotion of the Arts of ments. The Imperial A. of Sciences of St. Petersburg was Design, Painting, Sculpture, etc. The Royal Scottish A. of planned in 1724 by Peter the Great, with the advice of Leib- Painting, Sculpture, and Architecture was founded at Edinnitz and Wolf. It was established in the following year by burgh in 1825, and received a royal charter in 1838. Similar Catherine I., and liberally supported by the empress; fifteen to these also is the Royal Hibernian A., incorporated at members received pensions as professors of various branches. Dublin in 1803. In Great Britain the term A. is chiefly conAfter various fluctuations the A. attained a position of high fined to associations for the promotion of the fine arts; those eminence and utility under the liberal patronage of Catherine for scientific purposes being styled societies. A similar usage II. Among the most important results of her liberality are the prevails in Am. The National A. of Sciences of the U. S., travels and researches of such men as Pallas and Klaproth. incorporated by Congress in 1863, was limited to 50 memThe A. of Sciences at Stockholm, founded in 1739, consisted bers, citizens of the U. S., 50 foreign associates, and a variat first of six members, one of whom was the celebrated able number of honorary members. The term is also used Linnæus. It received a royal charter in 1741, but no endow-to denote a school of high grade, as the U. S. Military A. at In 1799 it was divided into six classes: (1) Political West Point, and the Naval A., Annapolis, and to schools and Rural Economy, 15 members; (2) Commerce and Mechan-ranking between the common school and the college.

ment.

ACADIA-ACCELERATION.

Aca'dia, (Fr. Acadie, said to be derived from Shubenaca die, the name of one of the principal rivers of Nova Scotia; in the early grants called L' Acadie and La Cadie,) the original and now the poetic name of Nova Scotia. It was granted in 1603 to De Monts by King Henry IV. of France. In 1621 A. was by charter granted to Sir William Alexander, and from that time has been known as Nova Scotia. In the numerous disputes between the colonists of England and France previous to 1763 this territory changed masters ten or a dozen times, and the boundaries were widened or narrowed according to

27

Acarnaʼnia, a country of ancient Greece, separated from Epirus on the N. by the Ambracian Gulf, now the Gulf of Arta, from Ætolia on the E. by the River Achelous, and washed S. and W. by the Ionian Sea. Along with Etolia it forms one of the nomes or departments of the modern kingdom of Greece.

Ac'arus, a genus of Arachnides, the type of a tribe called Acarides. The species are very numerous. All of them are small. Some are familiar to us under the name of mites, ticks, etc. Some live upon the juices of plants, some in the dung of animals; many species are found in the vegetable and animal substances used for human food, especially when these have been kept for a considerable time, as in cheese, flour, sugar, on the surface of preserves, of dried fruits, etc.; others are parasites upon the bodies of animals, particularly in diseased conditions, as in cases of itch. A minute species has been detected in the follicles of the human skin, and others even in the human brain and eyes. Some insects, particularly beetles, are often covered with acarides. The acarides have eyes. Some of them have the mouth furnished with mandibles, others with a sucker. They are oviparous, and extremely prolific. They have generally eight legs, but when young many of them have only six, and in some genera the additional pair seems never to be acquired. A few are aquatic and have legs covered with hairs to adapt them for swimming. Ac'arus Folliculor'um is the most generally accepted name for a microscopic parasite residing in the sebaceous sacs and hair-follicles of the human skin. It is also known as the Demodex folliculorum. It was first described by Dr. Simon, of Berlin, in 1842, under the title of A. F. which was suggested by the eminent zoologist, Erichsen, of Berlin. In the following yr. Mr. Erasmus Wilson made it the subject of an elaborate memoir, which appeared in the Philosophical Transactions, in which, as there are doubts as to its exact zoological position, he simply terms it the Entozoon folliculorum. According to Prof. Owen, who gave it the name of Demodex, it represents the lowest form of the class Arachnida, and makes a transition from the Annelids to the higher Articulata. As regards the size and form of these animals there is much variety; they pass their whole existence in the fatty matter of the sebaceous cells, molting repeatedly during their growth, and being finally expelled from the follicles with the secretions of these organs. They are met with in almost every person, but are most numerous in those in whom the skin is torpid, in invalids and in the sick. They vary in length from 0 to 100 of an in.

Ac'arus Scabiei, or Sarcoptes hominis, is a small, round

Acale'phæ, (Gr. "nettles,") a term given by Aristotle to the jelly-fishes, or Meduside, and their allies, in allusion to their stinging propensities. The true jelly-fishes, or Medusidæ, constitute the sub-class Discophora, and are distinguished by being free-swimming forms, the body in each being more or less bell-shaped, and being composed of a clear gelatinous swimming-bell or nectocalyx, from the roof of which the mouth is suspended; while throughout the substance of the bellshaped body a system of radial and circular canals is distrib-ish animal, just visible to the naked eye. When viewed under uted. These organisms, familiar to every sea-side visitor, a microscope it is seen to be flattened, and to resemble a torswim gracefully by contracting and expanding their clear toise in shape. When fully developed it has eight legs, and jelly-like bodies. They feed on minute crustacea, fishes, and on its under surface are scattered filaments and short spines, the like, and very many exhibit a phosphorescent light or which are for the most part directed backward. The female animal luminosity. is the larger; the male lives near the surface of the skin; the female burrows within the cuticle, and deposits from ten to fifteen eggs in the cuniculus or burrow; these eggs hatch in about a fortnight. The young acari escape from the burrow, but the parent does not leave it, and dies when she has finished laying eggs. The A. S. is the cause of the skin affection called scabies or itch. See ITCH.

Acanthas'pis, fossil-fishes found in the limestone of Ohio; buckler-headed, and somewhat resembling cephalaspis. Acan'thophis, native serpents of Australia, allied to the viper; tail ending in a horny spine. The adder is included in the genus.

Acanthopteryg'ii, in Zool., one of the two primary divisions of the osseous fishes in the system of Cuvier, distinguished by having spinous rays in the first portion of the dorsal fin, or in the first dorsal if there are two. The name is derived from the Greek akantha, a thorn, and pteryx, a wing. The A. are divided by Cuvier into fifteen families, among which are perch, bass, flying-fish, mackerel, etc.

Perch.

Acan'thurus, or sea-surgeon, Amer. tropical fish, found also in Africa with a sharply pointed and edged spine on the side of its tail.

Acan'thus, the name given by the Greeks and Romans to the plants sometimes called Brancursine, of which it is also the botanical generic name. A. mollis and A. spinosa, natives of the S. of Europe, are the species best known. The beautiful forms of their leaves have led to their artistic application in architecture, etc.

A capella, or A la capella, in Mus. See FOREIGN PHRASES in the APPENDIX.

Acapulco, the best harbor of Mexico, on the Pacific, and a place of considerable commercial importance; has a very unhealthy site, and is one of the places most frequently visited by the cholera; pop. about 3,000. It formerly monopolized the Spanish trade with the East Indies.

Acathis'tus, a hymn sung in the ancient Greek Church in honor of the Virgin.

Acayucan', a town of Mexico, about 100 m. S.-S.-E. of Vera Cruz, with a good trade in cochineal; pop. 6,000.

Ac'ca Lauren'tia, variously considered as the foster mother of Romulus, and as a rich widow who left all her property to the Roman people.

Acceleran'do, in Mus. See FOREIGN PHRASES in the APPENDIX.

Accelera'tion, in Mechanics, is the change in velocity impressed upon a body by the action of some force. The body may be either at rest or in motion, and the force may be applied in any direction, and the result will be that the change in velocity will be in the direction of the application of the force and directly proportional to it. If the force is constant the acceleration will be uniform. A body near the surface of the carth falling freely toward its center in a vacuum moves with nearly uniformly positively accelerated motion, and if thrown vertically upward in a vacuum and left to itself will continue upward with nearly uniformly negatively accelerated motion till its velocity becomes zero, when it will at once start down with positive A. Much confusion has at times arisen in the discussion of certain phenomena, notably those of earthquakes, from confounding A., or change of velocity, with absolute velocity itself. The first is a measure

28

ACCELERATION OF THE FIXED STARS-ACCUBATION.

of the amount of force acting at the instant in question, a cause, or prosecuting it against the heir of a deceased while the latter is a measure of the accumulated work of defendant, or for restoring lost deeds or other documents, all previously acting forces, and will remain constant, till are of the nature of A. A. further force is brought to bear, both in amount and direction.

Accelera'tion of the Fixed Stars is a term, but little used to-day, to denote the amount of time by which the stars come to the meridian each day ahead of, or sooner than, the sun. It is of course the difference between a sidereal and a solar day, amounting, on the average, to 3′ 55.9′′ of mean solar time. It is caused by the motion of the earth round the sun, which makes the latter appear to move eastward among the stars, and hence come to the meridian each day later than they really do.

Acces'sory Obliga'tion is a technical term in law signifying an obligation annexed to another obligation which is antecedent or primary. Thus, an obligation for the regular payment of interest, or by way of further security, is an A. O. Ac'cident, in equity jurisprudence, has been defined to be such an unforeseen event, misfortune, loss, or omission as is not the result of negligence or misconduct. Some of the leading cases of interference by the court are (1) Where negotiable or other instruments have been lost, and there is no adequate remedy in a court of law. (2) Where a clause has been inadvertently omitted from or inserted in an instrument, the court makes the instrument conform to the intent of the parties. (3) Cases of omission, through inadvertence

court has power to allow the necessary steps to be taken. It is a general rule, in cases of accident, that relief will not be granted against a purchaser who has acquired legal rights in good faith and for a consideration.

Accident'als, in Mus., occasional sharps, flats, and naturals placed before notes in the course of a piece.

Accelera'tion of the Moon's Motion. It was first observed by Halley that the time of the moon's revolution round the earth has for several thousand years been decreas-or want of knowledge of facts, to defend an action. The ing, or her velocity has been increasing. This phenomenon remained for a considerable time inexplicable; at last Laplace, in 1787, discovered the cause in the varying eccentricity of the earth's orbit, which has been on the decrease since about 12,000 years B.C. Since that time the moon has been gradually coming nearer to the earth; and this will go on till 36,900 years after Christ, when the eccentricity of the earth's orbit will begin again to increase. Although the cause thus discovered accounts for the greater part of the observed acceleration, there is still a sufficient amount of difference between theory, and observation to make the problem a troublesome one for astronomers, the theory of the moon's motion being the most difficult problem ever attacked by mathematicians.

Ac'cent, in Grammar, is a special stress of voice laid upon one syllable of a word, by which it is made more prominent than the rest. Every word in English has one syllable thus brought markedly into notice. When the accented syllable falls near the end of a long word there may be one or more secondary accents. It is A., and not quantity, that determines English measures or meters in versification. No rule can be given as to what syllable of a word shall be accented. Tere seems to be an increasing tendency in our language to throw the A. toward the beginning of words. Ac'cent, in Mus., is analogous with A. in language. It consists of a stress or emphasis given to certain notes or parts of measures in a composition, and may be divided into two kinds-grammatical and rhetorical, or æsthetic. Accent'or, song-birds of Europe introduced into U. S. Small, brown above and steel-colored beneath.

Acceptance is the act whereby the drawee engages to pay a bill according to the terms of the A. It may be said to consist in the drawee writing the word "accepted" on the bill, and subscribing his name.

Accept'ants, or Constitu'tionists, Fr. Jesuits who accepted the bull of Clement XI., 1713.

Acces'sion. In Law, property may be acquired by A., and this A. may be either natural or artificial. The young of cattle and other animals, for example, belong to the person who is the owner of the mother, and the fruits and produce of the earth to the proprietor of the soil; and for the same reason the gradual addition to lands on the bank of a river belongs to the proprietor of the land receiving the addition. These are instances of natural A. Property, again, is said to be acquired by artificial A. when it is the result of human industry.

Acces'sion, Deed of, a deed by which the creditors of a bankrupt or insolvent debtor approve of a trust-settlement executed by the debtor for the general behoof, and consent to the arrangement proposed; a deed of trust for creditors. Acces'sion to the Throne signifies the commencement of the sovereign's reign.

Acces'sory or Acces'sary. In Criminal Law an A. is a person who is not the chief actor in a felony, nor even present at its perpetration, but who is in some way concerned either before or after the fact or act committed. An A. before the fact is one who procures or counsels another to commit a crime, he himself being absent. An A. after the fact is a person who, knowing a felony to have been committed, receives, protects, or assists the felon. In sudden and unpremeditated offenses there can be no accessories before the fact; and in all crimes under the degree of felony there are no accessories at all, either before or after the fact, but all persons concerned therein are held to be equally guilty as principals.

Ac'cidents, in Logic, are opposed to essentials, or to
substance. An accident is the property of an object which
may be modified, or even be altogether abstracted, without
the object ceasing to be essentially what it is.
Accip'iters, (pl. of the

Lat. accipiter, a hawk,) the
name given by Linnæus to
an order of birds including,
according to his system, the
genera Vultur, (vultures,)
Falco, (eagles, falcons,
hawks, etc.,) Strix, (owls,)
and Lanius, (shrikes,) and
principally distinguished by
a hooked bill, short strong
feet, and sharp hooked claws.
Acclimatize, to accustom an animal or plant to a
climate not natural to it. The process, of course, varies
widely, according to the amount of difference between the
old climate and the new.

Head and Foot of one of the
Accipiters.

Accolade', the term applied to the ceremony with which a knight was admitted into the order of chivalry. The grand master, in receiving the neophyte, embraced him by folding the arms around the neck, (ad collum.)—In Mus., the A. is the couplet uniting several staves, as in part-music or. piano-forte music.

Accol'ti, (BENEDETTO,) Chancellor of Florence 1459, wrote a history of the Crusades, which served as inspiration to Tasso; b. 1415; d. 1466.

Accom ́paniment, in Mus., is the assisting or aiding of a solo part by other parts, which may consist of a whole orchestra, or a single instrument, or even subservient vocal parts. It serves to elevate and beautify the solo part, and is subject to certain rules for composition as well as for performance.

Accom'plice, one connected with a crime, either as accessory or principal, sometimes applied to those who testify against each other.

Accord' and Satisfac'tion, an agreement to give and receive something as compensation for injury and its performance.-In Mus., A. is synonymous with concord. Accordion, a simple musical instrument, but little better than a toy, which produces its tones by the vibration of metallic tongues of various sizes, while wind is supplied by the action of bellows. The concertina and the harmonium are superior instruments, constructed on the same principle-the action of a gust of air on metallic tongues.

Accordion.

Account', a record of receipts and expenditures, called current when still unsettled, stated when closed; a formal statement of the dealings of two parties.

Accre'tion, land gradually formed by water deposits along the shore of a river or sea, belonging, except in cases of sudden formation, to property owners adjacent. See ACCESSION.

Ac'crington, a manufacturing town of England, in Lancashire; pop. about 40,000.

Acces'sory Ac'tions, in Law, are those which are sub- Accuba tion, the reclining posture observed by ancient servient to other actions. For example, actions for reviving | Romans and Orientals at meals; invented by the Greeks.

Ac'cum, (FREDERICK,) a native of Westphalia, was Prof. improvements in the process of preparing sugar from of Chemistry in Surrey Institute, London, 1801-22. He is beet-root. known on account of his Practical Treatise on Gas-lights, which had the effect of introducing that method of illumination into London and all the large towns of Eng. B. 1769, d. 1838.

Accu'mulated Force, the excess of force communicated to a body to overcome resistance and produce motion. As power is each instant imparted to the body, the constant application of a very small force will at length communicate rapid motion and great momentum.

Achelo'us, now called Aspropot'amo, (i. e., White River, from the cream color of its waters,) the largest river in Greece, rises in Mount Pindus, flows through the land of the Dolopians, divides Etolia from Acarnania, and falls into the Ionian Sea.

A'chenbach, (ANDREAS,) a distinguished landscape and marine painter, b. at Cassel, Sept. 29, 1815; d. Oct. 2, 1884. OSWALD A., a brother of the above, b. Feb. 2, 1827, at Dusseldorf, has considerable reputation as a

Achenium.

Ache'nium, Acho'nium, or Ake'nium, a term employed by botanists to designate a dry, hard, one-seeded, indehiscent fruit or pericarp, as the rose or buttercup; called a naked seed by the earlier botanists.

Aceph'alocysts (Gr. à кɛọaλo, "without a head," and κύστις, a bladder,”) a hydatiform vesicle, or bladder, with-landscape painter. out head or visible organs, ranked among the Entozoa, although possessed of a few animated characteristics. In no organ of the body are A. so frequently found as in the liver. They vary in size from a pin's head to that of a child, and are found in various parts of the body of man. They were formerly considered as parasitic animals, but are now known to be scolices of cestoid worms. The Acephalocystis endogena of John Hunter and the A. exogena of Kuhl are merely varieties of the true hydatid, (Echinococcus veterinorum, E. hominis.) See HYDATIDS.

Acer'ra, a town in Italy, in the prov. of Caserta; pop. 15,768.

Ace'tal is a colorless liquid, of an agreeable odor and a flavor said to resemble that of the hazel-nut. It is one of the products of the slow oxidation of alcohol under the influence of finely divided platinum, or of chlorine, or of diluted sulphuric acid and peroxide of manganese.

Acetic Acid, (Lat. acetum,) the sour principle in vinegar, is the most common of the vegetable acids. If alcohol, diluted with water, be mixed with a ferment, such as yeast, and exposed to the air at, or a little above, its ordinary temperature, it is rapidly converted into vinegar or A. A. The change is accompanied by the absorption of oxygen, two atoms of which combine with as many of hydrogen to form water, while other two take the place of the hydrogen which has become water, so that A. A. is produced from alcohol by the substitution of two atoms of oxygen for two of hydrogen. A totally new view has been adopted regard ing the process by which wine, beer, cider, and alcoholic fluids generally become converted into A. A. when they are exposed to the action of the air, and Pasteur maintains that the true acetifying matter is a very minute mycoderma -a special vegetable organized being. It is impossible to conceive a more simple form of vegetation, consisting of extremely minute spores arranged in chains, each spore having a mean diameter not exceeding of an in., and the length being about twice as great. The rapidity of the development of these spores under favorable circumstances is almost inconceivable; and the power which they possess of fixing the oxygen of the air, and of transmitting it to the alcohol, and of establishing an incomplete combustion of the latter, is no less wonderful. A surface of a square yard covered with this plant is able, in the course of 24 hours, to fix the oxygen of more than 1,000 quarts of air.

Acet'ic Anhydride, a colorless odorous liquid, the result of the action of oxychloride of phosphorus on acetate of potassium.

Achernar', (Arab. akher an nahr, "the end of the river,") the star Alpha Eridani, at the southern end of the winding river Eridanus.

Ach'eron, the name given to several rivers by the ancients, always with reference to some peculiarity, such as black or bitter waters, or mephitic gases: the A. in Thesprotia, which flows through the lake Acherusia, and pours itself into the Ionian Sea; another river in Elis, now called Secuto; and several streams in Egypt, supposed to have some communication with the infernal world.

Acheron'tia, or Death's Head Moth, a handsome European insect, on whose back is a remarkable represen tion of a skull; makes a squeaking noise when disturbed.

A-cheval' Posi'tion. When troops are arranged so that a river or highway passes through the center and forms a perpendicular to the front, they are said to be drawn up in A. P.

Ach'ill, or Eagle Isle, off the W. coast of Ireland, is reckoned within County Mayo. It is 15 m. 1. by 12 m. w. and has a very irregular coast-line, though its general shape is almost that of a right-angled triangle; pop. 6,700. On the coast is a precipice 2,200 ft. h.

Achillæ'a, a genus of plants of the natural order Composite, having small flowers (heads of flowers) disposed in corymbs, and the receptacle covered with chaffy scales, (small bracteæ.) The florets of the ray are female, and have a short, roundish tongue, or lip; the florets of the disk are hermaphrodite, the tube of the corolla flatly compressed and two-winged; the involucre is imbricated. The common yarrow or milfoil (A. millefolium) abounds in some parts of North America and in all parts of Europe. It is about a ft. in h., its leaves bipinnate, the pinnæ deeply divided, the segments narrow and crowded. It has white or rose-colored flowers.

Achilles, the hero of Homer's Iliad, was the son of King Peleus and Thetis, a sea-goddess belonging to a line descended from Jove. We are told that he was dipped in the river Styx by his mother, and was thus made invulnerable except in the heel, by which he was held during the process. It had been prophesied at his birth that his life would be short, and therefore, when the seer Calchas announced that without A. Troy could not be taken, his mother, to keep

Acetpheno'tidine, a compound of acetyle with pheno-him from the dangers of the expedition, concealed him at tidine, analogous to the composition of acetanilide, discovered by Hinsbarg and Kast. It is given to reduce temperature in fevers in doses of three to eight grains. It occurs in colorless or faintly reddish needles, almost insoluble in water, and easily soluble in alcohol or diluted acetic acid. It is tasteless, and in large doses produces sleepiness, uncertain gait, vomiting, and at last blueness of the mucous membranes of the mouth.

Ac'etyle, known also under the names Acetoxyl and Othyl, is an organic radical not yet isolated, but which is supposed to exist in acetic acid and its derivatives. The reason for assuming the existence of this radical in the acetic compounds is that the formula to which it leads affords the simplest explanation of the most important reactions of acetic acid.

Acha'ia, a small district in the N. of the Peloponnesus, was anciently divided into 12 little states. In the modern kingdom of Greece it forms, with Elis, the nomarchy of A. and Elis; area, 1,901 sq. m.; pop. 210,713.

Achalganj', a town of British India, in the S. part of the chief-commissionership of Oudh; pop. 5,000.

Achard', (FRANZ KARL,) Ger. naturalist and chemist, b. in Berlin 1753, d. 1821; chiefly distinguished himself by his

the court of King Lycomedes, among whose daughters the boy lived disguised as a girl. But Ulysses discovered him by a stratagem. A. in the Greek campaign against Troy appeared with 50 vessels manned by his followers, the Myrmidons, but remained sullen and inactive during a great part of the contest. We are told that soon after the fall of Hector, A. made a contract of marriage with Polyxena, the daughter of the Trojan king, but was slain by her brother, Paris, in the temple of Apollo, where the marriage should have been celebrated. According to other accounts he was slain by Apollo, who assumed the likeness of Paris as a disguise. Achilles, (TATIUS,) an Alexandrian rhetorician and novelist of the 5th c.

Achilles's Ten'don, (Tendo Achillis,) attaches the soleus and gastrocnemius muscles of the calf of the leg to the heel-bone. It is capable of resisting a force equal to 1,000 lbs. weight, and yet is frequently ruptured by the contraction of these muscles in sudden extension of the foot. Ancient surgeons regarded wounds or serious bruises of the A. T. as fatal.

Achil'li, (GIOVANNI GIACINTO,) issued the best Italian version known of the New Testament. He was at first a Dominican, but became a Protestant; b. 1803.

Ac'ne is an important skin disease. The sebaceous folli-ical science. Newton showed by calculation how the propacles of the skin are the primary seat of the affection. Their natural secretion accumulates in their interior, and there is, at the same time, a tendency to inflammation of the follicle and surrounding tissue. It is by no means rare to find on the face and shoulders of young persons, about or above the age of puberty, a number of black spots, each of which is placed on a slightly raised pale base. These black points are called comedones. Interspersed are other spots, with the base more raised and inflamed, which become more or less perfect pustules, each of which rests on a comparatively large red base. In some of the inflamed follicles coagulated lymph (to use the old phraseology) is thrown out, and a small hardened mass is the result. According as one or other of these appearances preponderates we have different varieties of this disease. As long as there is no inflammation the treatment simply aims at favoring the escape of the contents of the sebaceous follicles by rubbing the face and other affected parts with cold cream at bedtime, washing the next morning with soap and water, and gentle subsequent friction with a soft towel. When acute Ladammation is present, and the pustules are very tender, there is no better application than tepid water with or without a little gelatine in solution, and subsequently the oint