Recurring or reappearing from time to time; intermittent.
Characterized by periodic sentences.
pe'ri·od'i·cal·ly adv.
Synonyms: These adjectives all mean recurring or reappearing now and then. Something periodic occurs at regular or at least generally predictable intervals: periodic feelings of anxiety. Sporadic implies scattered, irregular, unpredictable, or isolated instances: sporadic bombing raids. Intermittent describes something that stops and starts at intervals: intermittent rain showers.
What is occasional happens at random and irregularly: occasional outbursts of temper.
Something fitful occurs in spells and often abruptly: fitful bursts of energy.
Usage Note: In technical use, periodic means "at regular or predictable intervals," as in the Periodic Table of the Elements. Often, however, periodic is used to mean "occasional, intermittent." This usage can be confusing for readers who are accustomed to the narrower sense of the word. Thus the writer who says Parker's losses at the track were not covered by his periodic wins invites the (most likely unintended) inference that Parker has a system that enables him to win at regular intervals. The ambiguity can be avoided here by using occasional instead.
1642, from Fr. périodique (14c.), from L. periodicus, from periodus (see period). Periodical "magazine that publishes regularly" is first attested 1798. Periodic table in chemistry is from notion of the arrangement, in which similar properties recur at intervals in elements in the same area as you read down the rows of the table. This sense of the word is attested fromj 1872.
El"e*ment\, n. [F. ['e]l['e]ment, L. elementum.]1. One of the simplest or essential parts or principles of which anything consists, or upon which the constitution or fundamental powers of anything are based. 2. One of the ultimate, undecomposable constituents of any kind of matter. Specifically: (Chem.) A substance which cannot be decomposed into different kinds of matter by any means at present employed; as, the elements of water are oxygen and hydrogen. Note: The elements are naturally classified in several families or groups, as the group of the alkaline elements, the halogen group, and the like. They are roughly divided into two great classes, the metals, as sodium, calcium, etc., which form basic compounds, and the nonmetals or metalloids, as oxygen, sulphur, chlorine, which form acid compounds; but the distinction is only relative, and some, as arsenic, tin, aluminium, etc., form both acid and basic compounds. The essential fact regarding every element is its relative atomic weight or equivalent. When the elements are tabulated in the order of their ascending atomic weights, the arrangement constitutes the series of the Periodic law of Mendelejeff. See Periodic law, under Periodic. This Periodic law enables us to predict the qualities of unknown elements. The number of elements known is about seventy-five, but the gaps in the Periodic law indicate the possibility of many more. Many of the elements with which we are familiar, as hydrogen, carbon, iron, gold, etc., have been recognized, by means of spectrum analysis, in the sun and the fixed stars. From certain evidence (as that afforded by the Periodic law, spectrum analysis, etc.) it appears that the chemical elements probably may not be simple bodies, but only very stable compounds of some simpler body or bodies. In formulas, the elements are designated by abbreviations of their names in Latin or New Latin. The Elements ------------------------------------------------------------ Name |Sym-|Atomic Weight| |bol | O=16 | H=1 | ------------------------------------------------------------ Aluminum | Al | 27.1 | 26.9| Antimony(Stibium) Argon Arsenic Barium Beryllium (see Glucinum) Bismuth Boron Bromine Cadmium Caesium Calcium Carbon Cerium Chlorine Chromium Cobalt Columbium Copper (Cuprum) Erbium Fluorine Gadolinium Gallium Germanium Glucinum Gold Helium Hydrogen Indium Iodine Iridium Iron (Ferrum) Krypton Lanthanum Lead (Plumbum) Lithium Magnesium Manganese Mercury (Hydrargyrum) Molybdenum Neodymium Neon Nickel Niobium (see Columbium) Nirogen Osmium Oxygen Palladium Phosphorus Platinum Potassium (Kalium) Praseodymium Rhodium Rubidium Ruthenium ----------------------------------------------------------- The Elements -- continued ------------------------------------------------------------ Name Samarium Scandium Selenium Silicon Silver (Argentum) Sodium (Natrium) Strontium Sulphur Tantalum Tellurium Thallium Thorium Thulium Tin (Stannum) Titanium Tungsten (Wolframium) Uranium Vanadium Wolfranium (see Tungsten) Xenon Ytterbium Yttrium Zinc Zirconium ---------------------------------------------------------- Note: Several other elements have been announced, as holmium, vesbium, austrium, etc., but their properties, and in some cases their existence, have not yet been definitely established. 3. One of the ultimate parts which are variously combined in anything; as, letters are the elements of written language; hence, also, a simple portion of that which is complex, as a shaft, lever, wheel, or any simple part in a machine; one of the essential ingredients of any mixture; a constituent part; as, quartz, feldspar, and mica are the elements of granite. The simplicity which is so large an element in a noble nature was laughed to scorn. --Jowett (Thucyd.). 4. (a) One out of several parts combined in a system of aggregation, when each is of the nature of the whole; as, a single cell is an element of the honeycomb. (b) (Anat.) One of the smallest natural divisions of the organism, as a blood corpuscle, a muscular fiber. 5. (Biol.) One of the simplest essential parts, more commonly called cells, of which animal and vegetable organisms, or their tissues and organs, are composed. 6. (Math.) (a) An infinitesimal part of anything of the same nature as the entire magnitude considered; as, in a solid an element may be the infinitesimal portion between any two planes that are separated an indefinitely small distance. In the calculus, element is sometimes used as synonymous with differential. (b) Sometimes a curve, or surface, or volume is considered as described by a moving point, or curve, or surface, the latter being at any instant called an element of the former. (c) One of the terms in an algebraic expression. 7. One of the necessary data or values upon which a system of calculations depends, or general conclusions are based; as, the elements of a planet's orbit. 8. pl. The simplest or fundamental principles of any system in philosophy, science, or art; rudiments; as, the elements of geometry, or of music. 9. pl. Any outline or sketch, regarded as containing the fundamental ideas or features of the thing in question; as, the elements of a plan. 10. One of the simple substances, as supposed by the ancient philosophers; one of the imaginary principles of matter. (a) The four elements were, air, earth, water, and fire; Note: whence it is said, water is the proper element of fishes; air is the element of birds. Hence, the state or sphere natural to anything or suited for its existence. Of elements The grosser feeds the purer: Earth the Sea; Earth and the Sea feed Air; the Air those Fires Ethereal. --Milton. Does not our life consist of the four elements? --Shak. And the complexion of the element [i. e.,the sky or air] In favor's like the work we have in hand, Most bloody, fiery, and most terrible. --Shak. About twelve ounces [of food], with mere element for drink. --Cheyne. They show that they are out of their element. --T. Baker. Esp., the conditions and movements of the air. "The elements be kind to thee." (b) The elements of the alchemists were salt, sulphur, and mercury. --Brande & C. 11. pl. The whole material composing the world. The elements shall melt with fervent heat. --2 Peter iii. 10. 12. pl. (Eccl.) The bread and wine used in the eucharist or Lord's supper. Magnetic element, one of the hypothetical elementary portions of which a magnet is regarded as made up.
Law\ (l[add]), n. [OE. lawe, laghe, AS. lagu, from the root of E. lie: akin to OS. lag, Icel. l["o]g, Sw. lag, Dan. lov; cf. L. lex, E. legal. A law is that which is laid, set, or fixed; like statute, fr. L. statuere to make to stand. See Lie to be prostrate.]1. In general, a rule of being or of conduct, established by an authority able to enforce its will; a controlling regulation; the mode or order according to which an agent or a power acts. Note: A law may be universal or particular, written or unwritten, published or secret. From the nature of the highest laws a degree of permanency or stability is always implied; but the power which makes a law, or a superior power, may annul or change it. These are the statutes and judgments and law, which the Lord made. --Lev. xxvi. 46. The law of thy God, and the law of the King. --Ezra vii. 26. As if they would confine the Interminable . . . Who made our laws to bind us, not himself. --Milton. His mind his kingdom, and his will his law. --Cowper. 2. In morals: The will of God as the rule for the disposition and conduct of all responsible beings toward him and toward each other; a rule of living, conformable to righteousness; the rule of action as obligatory on the conscience or moral nature. 3. The Jewish or Mosaic code, and that part of Scripture where it is written, in distinction from the gospel; hence, also, the Old Testament. What things soever the law saith, it saith to them who are under the law . . . But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets. --Rom. iii. 19, 21. 4. In human government: (a) An organic rule, as a constitution or charter, establishing and defining the conditions of the existence of a state or other organized community. (b) Any edict, decree, order, ordinance, statute, resolution, judicial, decision, usage, etc., or recognized, and enforced, by the controlling authority. 5. In philosophy and physics: A rule of being, operation, or change, so certain and constant that it is conceived of as imposed by the will of God or by some controlling authority; as, the law of gravitation; the laws of motion; the law heredity; the laws of thought; the laws of cause and effect; law of self-preservation. 6. In matematics: The rule according to which anything, as the change of value of a variable, or the value of the terms of a series, proceeds; mode or order of sequence. 7. In arts, works, games, etc.: The rules of construction, or of procedure, conforming to the conditions of success; a principle, maxim; or usage; as, the laws of poetry, of architecture, of courtesy, or of whist. 8. Collectively, the whole body of rules relating to one subject, or emanating from one source; -- including usually the writings pertaining to them, and judicial proceedings under them; as, divine law; English law; Roman law; the law of real property; insurance law. 9. Legal science; jurisprudence; the principles of equity; applied justice. Reason is the life of the law; nay, the common law itself is nothing else but reason. --Coke. Law is beneficence acting by rule. --Burke. And sovereign Law, that state's collected will O'er thrones and globes elate, Sits empress, crowning good, repressing ill. --Sir W. Jones. 10. Trial by the laws of the land; judicial remedy; litigation; as, to go law. When every case in law is right. --Shak. He found law dear and left it cheap. --Brougham. 11. An oath, as in the presence of a court. [Obs.] See Wager of law, under Wager. Avogadro's law (Chem.), a fundamental conception, according to which, under similar conditions of temperature and pressure, all gases and vapors contain in the same volume the same number of ultimate molecules; -- so named after Avogadro, an Italian scientist. Sometimes called Amp[`e]re's law. Bode's law (Astron.), an approximative empirical expression of the distances of the planets from the sun, as follows: -- Mer. Ven. Earth. Mars. Aste. Jup. Sat. Uran. Nep. 4 4 4 4 4 4 4 4 4 0 3 6 12 24 48 96 192 384 -- -- -- -- -- -- -- --- --- 4 7 10 16 28 52 100 196 388 5.9 7.3 10 15.2 27.4 52 95.4 192 300 where each distance (line third) is the sum of 4 and a multiple of 3 by the series 0, 1, 2, 4, 8, etc., the true distances being given in the lower line. Boyle's law (Physics), an expression of the fact, that when an elastic fluid is subjected to compression, and kept at a constant temperature, the product of the pressure and volume is a constant quantity, i. e., the volume is inversely proportioned to the pressure; -- known also as Mariotte's law, and the law of Boyle and Mariotte. Brehon laws. See under Brehon. Canon law, the body of ecclesiastical law adopted in the Christian Church, certain portions of which (for example, the law of marriage as existing before the Council of Tent) were brought to America by the English colonists as part of the common law of the land. --Wharton. Civil law, a term used by writers to designate Roman law, with modifications thereof which have been made in the different countries into which that law has been introduced. The civil law, instead of the common law, prevails in the State of Louisiana. --Wharton. Commercial law. See Law merchant (below). Common law. See under Common. Criminal law, that branch of jurisprudence which relates to crimes. Ecclesiastical law. See under Ecclesiastical. Grimm's law (Philol.), a statement (propounded by the German philologist Jacob Grimm) of certain regular changes which the primitive Indo-European mute consonants, so-called (most plainly seen in Sanskrit and, with some changes, in Greek and Latin), have undergone in the Teutonic languages. Examples: Skr. bh[=a]tr, L. frater, E. brother, G. bruder; L. tres, E. three, G. drei, Skr. go, E. cow, G. kuh; Skr. dh[=a] to put, Gr. ti-qe`-nai, E. do, OHG, tuon, G. thun. Kepler's laws (Astron.), three important laws or expressions of the order of the planetary motions, discovered by John Kepler. They are these: (1) The orbit of a planet with respect to the sun is an ellipse, the sun being in one of the foci. (2) The areas swept over by a vector drawn from the sun to a planet are proportioned to the times of describing them. (3) The squares of the times of revolution of two planets are in the ratio of the cubes of their mean distances. Law binding, a plain style of leather binding, used for law books; -- called also law calf. Law book, a book containing, or treating of, laws. Law calf. See Law binding (above). Law day. (a) Formerly, a day of holding court, esp. a court-leet. (b) The day named in a mortgage for the payment of the money to secure which it was given. [U. S.] Law French, the dialect of Norman, which was used in judicial proceedings and law books in England from the days of William the Conqueror to the thirty-sixth year of Edward III. Law language, the language used in legal writings and forms. Law Latin. See under Latin. Law lords, peers in the British Parliament who have held high judicial office, or have been noted in the legal profession. Law merchant, or Commercial law, a system of rules by which trade and commerce are regulated; -- deduced from the custom of merchants, and regulated by judicial decisions, as also by enactments of legislatures. Law of Charles (Physics), the law that the volume of a given mass of gas increases or decreases, by a definite fraction of its value for a given rise or fall of temperature; -- sometimes less correctly styled Gay Lussac's law, or Dalton's law. Law of nations. See International law, under International. Law of nature. (a) A broad generalization expressive of the constant action, or effect, of natural conditions; as, death is a law of nature; self-defense is a law of nature. See Law, 4. (b) A term denoting the standard, or system, of morality deducible from a study of the nature and natural relations of human beings independent of supernatural revelation or of municipal and social usages. Law of the land, due process of law; the general law of the land. Laws of honor. See under Honor. Laws of motion (Physics), three laws defined by Sir Isaac Newton: (1) Every body perseveres in its state of rest or of moving uniformly in a straight line, except so far as it is made to change that state by external force. (2) Change of motion is proportional to the impressed force, and takes place in the direction in which the force is impressed. (3) Reaction is always equal and opposite to action, that is to say, the actions of two bodies upon each other are always equal and in opposite directions. Marine law, or Maritime law, the law of the sea; a branch of the law merchant relating to the affairs of the sea, such as seamen, ships, shipping, navigation, and the like. --Bouvier. Mariotte's law. See Boyle's law (above). Martial law.See under Martial. Military law, a branch of the general municipal law, consisting of rules ordained for the government of the military force of a state in peace and war, and administered in courts martial. --Kent. Warren's Blackstone. Moral law,the law of duty as regards what is right and wrong in the sight of God; specifically, the ten commandments given by Moses. See Law, 2. Mosaic, or Ceremonial, law. (Script.) See Law, 3. Municipal, or Positive, law, a rule prescribed by the supreme power of a state, declaring some right, enforcing some duty, or prohibiting some act; -- distinguished from international and constitutional law. See Law, 1. Periodic law. (Chem.) See under Periodic. Roman law, the system of principles and laws found in the codes and treatises of the lawmakers and jurists of ancient Rome, and incorporated more or less into the laws of the several European countries and colonies founded by them. See Civil law (above). Statute law, the law as stated in statutes or positive enactments of the legislative body. Sumptuary law. See under Sumptuary. To go to law, to seek a settlement of any matter by bringing it before the courts of law; to sue or prosecute some one. Totake, or have, the law of, to bring the law to bear upon; as, to take the law of one's neighbor. --Addison. Wager of law. See under Wager. Syn: Justice; equity. Usage: Law, Statute, Common law, Regulation, Edict, Decree. Law is generic, and, when used with reference to, or in connection with, the other words here considered, denotes whatever is commanded by one who has a right to require obedience. A statute is a particular law drawn out in form, and distinctly enacted and proclaimed. Common law is a rule of action founded on long usage and the decisions of courts of justice. A regulation is a limited and often, temporary law, intended to secure some particular end or object. An edict is a command or law issued by a sovereign, and is peculiar to a despotic government. A decree is a permanent order either of a court or of the executive government. See Justice.
Pe`ri*od"ic\, Periodical \Pe`ri*od"ic*al\, a. [L. periodicus, Gr. ?: cf. F. p['e]riodique.]1. Of or pertaining to a period or periods, or to division by periods. The periodicaltimes of all the satellites. --Sir J. Herschel. 2. Performed in a period, or regular revolution; proceeding in a series of successive circuits; as, the periodical motion of the planets round the sun. 3. Happening, by revolution, at a stated time; returning regularly, after a certain period of time; acting, happening, or appearing, at fixed intervals; recurring; as, periodical epidemics. The periodic return of a plant's flowering. --Henslow. To influence opinion through the periodical press. --Courthope. 4. (Rhet.) Of or pertaining to a period; constituting a complete sentence. Periodic comet (Astron.), a comet that moves about the sun in an elliptic orbit; a comet that has been seen at two of its approaches to the sun. Periodic function (Math.), a function whose values recur at fixed intervals as the variable uniformly increases. The trigonomertic functions, as sin x, tan x, etc., are periodic functions. Exponential functions are also periodic, having an imaginary period, and the elliptic functions have not only a real but an imaginary period, and are hence called doubly periodic. Periodic law (Chem.), the generalization that the properties of the chemical elements are periodic functions of their atomic wieghts. "In other words, if the elements are grouped in the order of their atomic weights, it will be found that nearly the same properties recur periodically throughout the entire series." The following tabular arrangement of the atomic weights shows the regular recurrence of groups (under I., II., III., IV., etc.), each consisting of members of the same natural family. The gaps in the table indicate the probable existence of unknown elements. TABLE OF THE PERIODIC LAW OF THE CHEMICAL ELEMENTS (The vertical columns contain the periodic groups) Series1[ 2[ 3[ 4[ 5[ 6[ 7[ 8[ 9[ 10[ 11[ 12[ -------------------------------------------------------------- |I. II. III. IV. V. VI. VII. VIII. | RH4 RH3 RH3 RH |R2O RO R3O3 RO2 R2O5 RO3 R2O7 RO4 -------------------------------------------------------------- H 1 Li 7 Na 23 K 39 (Cu) 63 Rb 85.2 (Ag) (108) Cs 133 (-) (-) (Au) (197) (-) --------------------------------------------------------------- Note: A similar relation had been enunciated in a crude way by Newlands; but the law in its effective form was developed and elaborated by Mendelejeff, whence it is sometimes called Mendelejeff's law. Important extensions of it were also made by L. Meyer. By this means Mendelejeff predicted with remarkable accuracy the hypothetical elements ekaboron, ekaluminium, and ekasilicon, afterwards discovered and named respectively scandium, gallium, and germanium. Periodic star (Astron.), a variable star whose changes of brightness recur at fixed periods. Periodic time of a heavenly body (Astron.), the time of a complete revolution of the body about the sun, or of a satellite about its primary.
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