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ARNOLD

Man,' 'Isolation, Faded Leaves,' and A ten almost entirely to members of his family Southern Night. The Forsaken Merman' has and close friends, and show him in the happiest passages of delightful fancy, and “The Church light. of Bron' displays imagination of a high order. Bibliography.-A bibliography of Arnold's The great merit of his verse is its uniform level writings was published by Thos. B. Smart in of fine thought, expressed with notable grace, 1893. His poetical works appeared as follows: clearness, and restraint.

(The Strayed Reveller, and Other Poems' As a critic Arnold has no superior and is (1849); Empedocles on Etna? (1852); (Powithout a rival in English literature. He made ems (1833; 3d ed. 1857); Poems, second far less errors than Johnson, was better in- series (1855); New Poems? (1867); and a formed than Dryden, was broader and more complete edition in three volumes 1885. His judicial than Pope. His judgments upon our critical works, beside those mentioned above, poets have become generally accepted and are were: 'On Translating Homer? (1861-2); Celtrarely questioned. His view of what criticism ic Literature (1867); Essays in Criticism, should be is given in the well-known essay on first series (1865); Mixed Essays (1879);

The Function of Criticism at the Present Irish Essays) (1882); Discourses in America/ Time'; in his own work and practice he seems (1885); Essays in Criticism, second series to have conceived its duty to be "to lay down de- (1888). Contemporary literature is filled with cisive canons of cultured judgment, to sift the criticism of the various aspects of Arnold's sound from the vicious, to maintain the purity of work. A few of the more important studies are: language and of style.” He greatly modified the Fitch, Thomas and M. Arnold (1897) ; Robaccepted form of the English critical essay and ertson, Modern Humanists' (1891); F. Harribrought it more into line with the French son, (Tennyson, Ruskin, and Mill, and Other causerie as developed by Sainte-Beuve, whose Literary Estimates) (1900), an excellent appreinfluence on Arnold was considerable. His ciation; Brownell, Victorian Prose Masters) characterizations of Spinoza, Marcus Aurelius, (1902); Walker, (The Greater Victorian Poets and Heine are masterly, and his appreciations of (1895) ; A. Galton, Two Essays Upon Matthew Wordsworth, Byron, and Goethe are without Arnold (1897). Prof. Saintsbury's volume on equals. The essays 'On Translating Homer Arnold is too hostile and unsympathetic to be are now classics. Homer's characteristics are of any critical value; and Mr. Herbert Paul's nowhere else set forth with such understanding, book in "The New Englishmen of Letters) series sympathy, and authority, or the rules of transla- is hopelessly futile and inadequate. tion so unanswerably deduced from them. His social, theological, and political criticism forms Providence, R. I., 1828; d. 1882. He was grad

Ar'nold, Richard, an American soldier: b. a distinct part of his work. He was thoroughly uated from West Point and served with disdiscontented with English indifference to ideas tinction in the Federal army during the Civil in literature, politics, and religion, and the ab- War, being brevetted major-general of volunsorption of his countrymen in material pursuits. teers in 1365. He made it his duty to arouse them from their intellectual apathy, and urge their attention to

Ar'nold, Samuel, an English composer: the higher things of life and the spirit. As a

b. London, 1740; d. 1802. In 1760 he was apconsequence he was greatly misunderstood and pointed a composer at the Covent Garden received much unmerited criticisin and contempt. Theatre, and set to music the Maid of the But his ideas had a marked influence on his

Mill.) He also produced the oratorios of the generation, and many of them have triumphantly Prodigal Son, the Resurrection, and others. prevailed. The books in which he carried on his He was made a doctor of music in 1773, and in crusade against British Philistinism) were:

1783 was appointed organist of the chapel royal. Culture and Anarchy) (1869); (Saint Paul He edited the works of Handel, in 36 volumes and Protestantism (1870); Friendship's Gar- folio. In 1794 he was made organist at Westland? (1871); Literature and Dogma) (1873); minster Abbey., In 1708 he composed his ora(God and the Bible (1875); Last Essays on

torio of Elijah. Various as were his comChurch and Religion (1877). He repeatedly positions, his inventive talent was but limited. evinced a happy faculty for doing the right His Cathedral Music was published in 1790. thing at the right moment. The storms of con- Ar'nold, Samuel Greene, an American histroversy and attack which his telling and keen torian: b. Providence, R. I., 12 April 1821; d. criticism of manners caused, never ruffled him, there, 12 Feb. 1880. He was graduated from or led him to retort in kind. His phrases be- Brown University in 1841, and traveled extencame current coin, his cutting "labels stuck to sively in Europe, South America, and the East. the things he satirized and have passed into He was lieutenant-governor of Rhode Island permanent use. This gift of sending forth 1852, 1851-2, and sat for part of a term in the phrases to ring through and be accepted by a

United States Senate 1862-3. He wrote a val. whole generation is a rare power. Forever as

uable History of Rhode Island and Providence sociated with him in the sense in which he Plantations (2 vols. 1860), and was for many used them are the now proverbial expressions, years president of the Rhode Island Historical “Philistinism, the great style, the young

Society. lions of the press, «the Zeit Geist," "the note Ar'nold, Thomas, an English scholar, of provinciality,” «sweet reasonableness,» «sweet- head-master of Rugby School, and professor of ness and light, the stream of tendency, not our- modern history in the University of Oxford • selves that makes for righteousness. It was his b. Cowes, Isle of Wight, 13 June 1795; d. 12 expressed wish that he should not form the June 1842. He received the elements of his subject of a biography. In 1895 his letters from education at Warminster, and at the age of 12 1848 to 1888 were gathered and edited in two was removed to the public school at Winchester. volumes by G. W. E. Russell. These were writ. Having obtained a scholarship in Corpus

ARNOLD - ARNOLFI

Christi College, Oxford, he entered that college Ar'nold, Thomas, an English writer on in his 16th year, and though naturally of a literature, and editor of old texts, son of Dr. shy disposition soon became remarked for the Arnold, of Rugby, and brother of Matthew Arboldness and independence of his views, and the nold: b. in Laleham, 30 Nov. 1823; d. 1900. He ability, firmness, and zeal with which he main- became a Roman Catholic, and spent a number tained them. In 1815 he was elected Fellow of of years in New Zealand and Tasmania. Among Oriel College, and both in that year and 1817 his works are A Manual of English Literaobtained the chancellor's prize for Latin and ture; Select English Works of Wyclif' (3 English essays. His views had been early vols., 1869); (Selections from the Spectator); directed to the Church, but some scruples as to Beowulf (text, translation, and notes); Hensigning the articles made him hesitate for a ry of Huntingdon'; 'Symeon of Durham'; and time. At length these scruples gave way before Chronicles of thé Abbey of Bury St. Eda more careful examination, and he took dea- munds'; Passages in a Wandering Life) con's orders in 1818. In 1819 he settled at (1900). His daughter is the novelist, Mrs. Laleham, near Staines, where he employed him. Humphry Ward. self in preparing young men for the universities, and in 1820 married the sister of one of his educator: b. Stamford, 1800; d. 1853. He was

Ar'nold, Thomas Kerchever, an English Penrose. About this time a remarkable change educated at Cambridge University, became an appears to have come over him; his religious Anglican clergyman; and published a large numviews became finally settled, and his whole mind ber of text-books for schools, including manuals appears to have been wound up to a determina- for the Greek, Latin, French, and German lantion to use life diligently and earnestly for the guages. best and holiest purposes. At Laleham he had Arnold of Brescia, är'nold of brěsh'a much leisure, which he employed partly in the (Arnaldo da Brescia), an Italian religious and cultivation of general literature, and partly_in political reformer and agitator: b. about 1100; writing articles on Roman history for the En- d. 1155. He was one of the disciples of Abelard, cyclopædia Metropolitana, and collecting ma- and on returning from Paris began to preach in terials for an edition of Thucydides, whose writ. his native city. In this way he stirred up the ings, as well as those of Aristotle, had long been people against the clergy; and in France, whither his favorites. In 1828, by the unanimous vote he was forced to flee in 1139, he also found nuof the trustees, who were told on high authority merous adherents, for the immorality and arrothat "he would change the face of education all gance of the clergy excited much discontent. through the public schools of England," he was The flame which he had kindled could not be exappointed head-master of Rugby School, and tinguished by the excommunication pronounced devoted himself to his new duties with the great- against him and his adherents by Innocent II. est ardor. While giving due prominence to the He preached his doctrines in safety at Zürich in classics, he deprived them of their exclusiveness Switzerland till about 1144, when he appeared at by introducing various other branches into his Rome, where his eloquence occasioned among course, and was particularly careful that the the people great disorder. The furious multieducation which he furnished should be in the tude, whom he himself could no longer restrain, liighest sense moral and Christian. His success revered him as their father, and even the Senate was remarkable. Not only did Rugby School protected him till Adrian IV., in 1155, laid an become crowded beyond any former precedent, interdict upon the city. This subdued the Robut its pupils on removing to the universities mans, and Arncld was obliged to flee. He was carried off a very large proportion of prizes, taken in Campania, and executed at Rome and and the superiority of Dr. Arnold's system be- his body burned; his ashes were thrown into came so generally recognized that it may be the Tiber, and his party was suppressed. His justly said to have done much for the general followers were known as Arnoldists. improvement of the public schools of England. In his position as a director of the London Uni

Ar'nold of Winkelried, wingskěl-rēd, a versity he zealously endeavored to extend the Swiss hero, who, at the battle of Sempach, in benefits of a literary and scientific education to 1386, sacrificed himself to insure victory to his all classes and creeds without excluding reli- countrymen. The Austrian knights, dismounted, gion; but failing in his efforts to make examina- had formed themselves into a phalanx, which the tion in the Scriptures requisite to obtain a degree, Swiss vainly strove to pierce, when Arnold, resigned his office. In 1841 he was appointed rushing on the spear points of the enemy, and professor of modern history at Oxford, and de- burying several in his breast, thus opened a gap livered his introductory course of lectures with in the fence of steel. The Swiss rushed in great success. The works by which Dr. Arnold through the opening, and routed the Austrians will continue to be best known are his edition with great slaughter. of Thucydides, his Roman History,' unhappily Ar'noldists. See ARNOLD OF BRESCIA. left unfinished, and his "Sermons, most of them prepared for his own chapel at Rugby, and so

Arnolfi, di Cambio, är-nol'fo dě käm'bio, admirably adapted to the circumstances of the or di Lapo, an Italian architect and sculptor: youths who formed the greater part of his audi- b. in Florence in 1232; d. in 1301. The most ence, that, though written hastily and at broken celebrated of his architectural works are the intervals snatched from other labors, they are churches of Santa Croce, the cathedral, and Or justly held to be models in their kind. See San Michele, at Florence, in which the gradual Stanley, Life and Correspondence of Thos. Ar- transition from the Gothic severity to the Italnold' (1860); Worboise, 'Life of Dr. Thos. ian elegance is markedly represented. This Arnold (1859); Fitch, Thomas and Matthew structure was completed, after the death of Arnold' (1897).

Arnolfi, by Brunelleschi, between 1420 and 1444. AROK-SZALLAS-AROMATIC COMPOUNDS

Arok-Szallas, ăr'ök-säläsh, or Jasz-AROK- hydrogen is replaced, and this fact indicates that Szallas, a privileged market-town in Hungary, the hydrogen atoms should occur in the struc44 miles northeast of Budapest. Pop. (1900) tural formula symmetrically. To reconcile II,190.

these considerations (and many others) Kekulé, Arolsen, ä'ről-sěn, a German town, capi- in 1865, proposed for benzene the structural for tal of the principality of Waldeck, on the river mula preceding. Aar. Rauch the sculptor was born here. Pop.

The symmetry of the body with respect to hy(1900) 2,734.

drogen is here evident, and the persistence of Aro'ma, a Greek term denoting perfume. carbon atoms to be united to one another in the

the group Co is explained by assuming the six Many plants yield a more or less delightful odor, form of a closed chain, supposed to possess often due to volatile oils called essences, which sufficient chemical strength to maintain its own can be separated from them by suitable pro- integrity, save under exceptional circumstances. cesses. Sometimes odor proceeds from a sub- The closed ring of six carbon atoms is the stance which cannot be seized, and to which the benzene nucleus,” referred to above, which conname of aroma is more particularly applied. It stitutes the distinctive feature of the aromatic appears that substances altogether, or almost compounds as a class. It will be observed that altogether, inodorous may be made to diffuse a in Kekulé's structural formula the carbon atoms strong odor by the mixture of different sub- are all tetravalent, just as they are in carbon stances which facilitate their volatilization. dioxid (CO2), and that three of the four valenThus, when musk is dried, ammonia is separated cies of each carbon atom are satisfied by the vafrom it, and seems to be the vehicle of the odor, lencies of other carbon atoms, while the fourth since the residuum becomes inodorous, and yet is satisfied, in each case, by a hydrogen atom. may again be made as odoriferous as it was at Von Baeyer has proposed a slightly different first by impregnating it with a quantity of the structural formula for benzene, even more syinsubstance which had been carried off. Tobacco, metrical in appearance than Kekulé's, but which in like manner, owes part of its odor to am

raises certain questions that are not yet anmoniacal salts mixed with it in the process of swered. His formula is as shown herewith. manufacture. One singular fact is that many

The closed carbon plants of tolerably strong odor yield an inodor

chain is present here ous liquid when dissolved in water and yet com

also, but only three municate odor to the oils with which they are

of the valencies of macerated. See PERFUMERY.

each carbon atom are Aromatic Compounds, a numerous and

HC

CH

definitely provided exceedingly important class of substances, fun

for, and it is asdamentally differing from the fatty compounds

sumed that the six in constitution, and named from the fact that

remaining valencies the earliest known representatives of the class

(one to each carbon HC

CH were resins, oils, and balsams, distinguished by

atom)

satisfied a marked aromatic odor. The name is now ap

by a sort of central plied to all substances containing a "benzene

linkage, whose prenucleus” (presently to be described). Benzene

cise nature is no itself is the simplest example of an aromatic

determined

debody. Its formula, expressed in the simplest fined. It is customary, at the present time way, is C&He, but when the attempt was made to express the structural formula of benzene is to represent the composition of benzene by a the simple form withstructural formula," numerous difficulties were out attempting any encountered. For example, benzene behaves like explanation of the a saturated compound in most respects, yet it fact that the carbon contains eight atoms less of hydrogen than the atoms are here apsaturated paraffin "hexane (CH) containing parently trivalent.

CH the same number of carbon atoms. Again, any Much thought has or all of the hydrogen atoms in benzene can been expended upon be replaced by other monovalent elements (or this matter, and the radicals); and the persistence of the group C. constitution of benin the derivations of benzene, even when all the zene is one of the HC

'original hydrogen most interesting prob-
atoms have been lems in the realm of
replaced by other organic chemistry.
elements or radi- The structural formu-
cals, indicates that las presented above are not to be taken in any
the carbon atoms sense as pictorial representations of the actual
in that body are geometrical configuration of the benzene mole-
intimately related cule. We know nothing at all about the shape
to one another, in of a molecule, nor about the way in which its

manner. parts are associated with one another, in space. Furthermore, it The structural formulas employed in chemistry has been proved are mere cmpirical diagrams, for representing, by experiment to the eye, the chemical properties and relations that the hydrogen' that have been observed in the laboratory. atoms in benzene Compounds have been prepared which conof

equal tain closed rings of three, four, and five atoms of value, so that it makes no difference, in form- carbon, respectively, but these are not classed ing a substitution compound, which atom of as aromatic compounds. They are intermediate,

are

or

нс,

CH

ION

HC

CH

Som e

HC

CH

are

AROMATIC COMPOUNDS

HC

are

SO

merest

or

CH

in general properties, between the aromatic se- when the second chlorine atom is separated from ries and the fatty series, but resemble the latter the first by one vortex which still retains its more closely. Compounds are also known in hydrogen, the product is known as meta-dichlowhich the chain is closed by an atom of oxygen, rcbenzene; and, finally, when the two substituted or of sulphur, or of nitrogen. Thus the struc- atoms of chlorine are opposite one another, the tural formula of pyridine is as shown herewith. product is known as para-dichlorobenzene. The

Such substances could three different dichlorobenzenes thus shown by be classed as (aro- the structural formula to be possible, are actualmatic compounds by ly known. All aromatic compounds having the an extension of the general formula C.H,Y, (where Y is a monova

definition of the aro- lent radical) occur in three isomeric series, just HC

CH

matic group, but are as the chlorobenzenes do, and the separate comusually regarded as pounds are distinguished, as already explained outside of the limits in the case of dichlorobenzene, by the prefixes of that group. The ortho-, meta-, and para-. These prefixes are

aromatic compounds frequently abbreviated to single letters, in works CH

numerous, on chemistry. Thus p- dihydroxybenzene is of

and include so many ten written in the place of the full name, "paraN

substances of tech- dihydroxybenzene. This particular substance

nical importance, that (used in pliotography and commoniy known as only the

outline of their general hydroquinone”), as its name implies, is formed character can be given in this place. In by the substitution of two molecules of hydroxyl general it may be said that they are derived (HO). for two atoms of hydrogen in the benfrom benzene by replacing one or more of its zene ring, the hydroxyl molecules being opposite typical hydrogen at ms by an equal number of each other (as indicated by the prefix para-). inonovalent radicals (either simple or com- Its structural formula, therefore, is as below. pound). The essential features of these substi- The ortho- compound tutions may be illustrated by considering the having the same com

C.OH chlorobenzenes. By the action of chlorine upon position (except that cold benzene, several substitution products are its

two hydroxyl formed, having the formulas C.H.CI, C.H..Cl2, molecules are in the

HC

CH C6H3.Cls, etc., according to the number of atoms (ortho” positions), is of hydrogen that are replaced by the chlorine. a different substance, The first of these substitution products, C.H.CI, known more familiaris called simply chlorobenzene, and it is to be ly as catechol, noted that since the hydrogen atoms in the orig- pyrocatechin, and the

HC inal benzene are all of equal value (that is, meta- compound all involved symmetrically), it makes no differ- (where the two mole

C.OH cnce which hydrogen atom is replaced by the cules of hydroxyl are chlorine; hence only one chlorobenzene having in the meta” positions) is quite different from the formula C.H..CI is possible. But when a either of the others, and is known as resorcinol. second atom of hydrogen is replaced by chlorine, The substitutions of monovalent radicals for the resulting compound, C.H..Cl. (known as di- the hydrogen atoms in benzene are by no means chlorobenzene), can exist in no less than three limited to two, nor need the radicals that are distinct isomeric forms, according to the rela- substituted be alike. Thus the pyrogallic acid tive positions of the chlorine atoms in the ben- so extensively used as a developer in photograzene ring. For let the structural formula of phy is obtained from benzene by the substituchlorobenzene (C.Hs.Cl) be represented by tion of three molecules of hydroxyl for three the skeletonized scheme the numbers represent- molecules of the benzene hydrogen; and it there.

ing the several groups fore has the formula C.H..(OH)3. Vanillin, CI

of CH, in one of now largely used in the place of extract of which the hydrogen vanilla for flavoring confectionery and ices, is

is to be replaced by benzene in which three atoms of the original i

a further substitution hydrogen have been replaced, respectively, by the of chlorine. It is

groups (CHO), (OCHz), and (OH). On acevident that the next

count of the typographical difficulties involved chlorine atom may replace a hydrogen

in printing the structural formulas of the aroatom at any one of

matic compounds, chemists often specify the 2

2
the five vertices to

constitution of these compounds by numbering which numbers have the original hydrogen atoms of the benzene from been attached; but it 1 to 6, and then specifying by number, which is also evident from hydrogen atom has been replaced by each of

symmetry that the the substituted radicals. Thus vanillin (retwo positions numbered "I must be considered ferred to in the previous paragraph) consists of as essentially identical, so far as the product re- benzene in which CHO has been substituted for sulting from a substitution is concerned, and the the first hydrogen atom, OCHz for the third, same is also true of the two positions marked and OH for the fourth; and with this conven"2.” Only three essentially different ways of tion the constitution of vanillin may be exsubstituting the second chlorine atom need there- pressed thus: CHO : OCH; : OH=1:3 : 4. fore be considered. When the second chlorine The existence of tertiary (and higher) subatom is situated at an angle adjacent to the first, stitution products of benzene makes it possible the product is known as ortho-dichlorobenzene; to identify the ortho-, meta-, and para- di-substiAROMATIC COMPOUNDS

tution compounds, so that the proper designation simpler and more familiar aromatic acids mostly can be attached to each of them. The di-bromo- contain one carboxyl group, and are therefore benzenes afford a good example of the way said to be "mono-carboxylic.". In the monoin which this is accomplished. The three essen- carboxylic group, benzoic acid, C.H..COOH, tially different compounds obtained by substitut- is "mono-hydric); salicylic acid. C.H..OH. ing bromine for two of the hydrogen atoms in COOH, is di-hydric”; proto-catechuic acid, benzene are (according to the notation just CoHz.(OH)..COOH, is “tri-hydric); and gallic given) Br : Br=1:2, Br : Br=1:3, and Br : acid, C.Hz.(OH)3.COOH, is tetra-hydric." Br=1:4, these being ortho-dibromobenzene, Numerous substances classed by the chemist as meta-dibromobenzene and para-dibromobenzene, alcohols also occur in the aromatic group. The respectively. Now if an atom of hydrogen in simplest of these and the only one containing the first of these be replaced by another atom only six atoms of carbon is phenyl aicohol, of bromine, it is evident that the new bromine which is also known as phenol, and as carbolic atom may have the position 3, 4, 5, or 6; but the acid. This substance is formed when benzene compounds in which the bromine occupies the is oxidized by peroxid of hydrogen, in accordpositions 1:2:3 and 1:2:6 must be regarded ance with the equation. as identical, as will be seen by constructing the C.H. + H202 C.H..OH + H.O. diagram; and, similarly, those in which it occu

Benzene. Hydrogen

Phenyl al- Water pies the positions 1 : 2:4 and 1:2:5 must be

peroxid. cohol. considered identical. Hence the further intro- Phenol is called an alcohol on account of its duction of bromine into ortho-dibromobenzene chemical structure (see ALCOHOL), but it differs. can give rise only to the two distinct tri-bromo- widely from the alcohols of the fatty series, benzenes 1:2:3 and 1 : 2:4. If the remaining since it does not yield an aldehyde, an acid nor dibromobenzenes be examined in the same way, a ketone, and it is not easily oxidized. Other it will be found that meta-dibromobenzene can aromatic alcohols may be prepared by replacyield (upon further bromination) the three dis- ing a hydrogen atom in benzene by one of tinct tri-bromobenzenes 1:2:3, 1:3:4, and the alcohol radicals (CnH2nti) of the fatty 1:3:5. Finally, it will be found that para-di- series, and then substituting an OH group for bromobenzene can yield only one tri-bromo- one of the hydrogen atoms in the compound so benzene; namely, 1:2 : 4.

The identification formed. The resulting substance has widely of a di-substitution bromobenzene as ortho-, different properties, according to the position meta-, or para- is therefore seen to be equivalent of the OH group so introduced. If the OH to determining how many different tri-bromo- replaces a hydrogen atom in the alcohol radical, benzenes the given di-bromobenzene can yield. the final compound is called an alcohol; but if This problem has been fully worked out in the it replaces a hydrogen atom in the original case here taken as an illustration, and it has benzene ring, the final compound_is more acbeen shown that of the three known di-bromo- curately classed as a phenol. For example, benzenes, the ortho- compound is the one boiling if CH, be substituted for an atom of hydrogen at 435° F., the meta- compound is the one boil- in benzene, toluene (C6H5.CH:) is formed. If, ing at 427°F., and the para- compound is the now, OH is substituted for a hydrogen atom in one melting at 180° F. The mode of identifica- the CH3, the resulting substance, C.H.CH,OH, tion here discussed in detail for bromine sub- is known as benzyl alcohol; while if the OH is. stitution products can be applied in other cases substituted for an H in the original ring, we also, but the labor involved in the operation is have C.H..(OH).CH, a substance known as so great that it is usually easier to ascertain the cresol, and more properly described as a phenol proper prefix for a new di-substitution com- than as an alcohol. One of the most important pound by noting which of the bromo-substitu- members of the aromatic group is amido-bention products must be used as a starting point, zene, or aniline (q.v.). in the synthesis of the proposed compound.

Á. D. RISTEEN, Ph.D., There is usually but little difference in the Editorial Staff, Encyclopedia Americana.' boiling points of ortho-, meta-, and para- com- Ar'omat'ics, plants (sometimes animal and pounds, but the para- compounds have the other substances) which have a spicy odor and highest melting points. The benzene ring of pungent taste and are used in medicine, cookery, ortho- compounds is liable to be broken up by and perfumery. They are largely employed to oxidation, while in the other two classes the disguise the taste of drugs, are usually reputed ring usually persists. The following general stimulant, antispasmodic, and, if bitter, tonic and law appears to hold true of di-substitution aro- vermifuge; externally they are applied as antimatic compounds: When a radical is introduced septics, local anæsthetics and counter-irritants. into a benzene ring in which one hydrogen Their active principles are volatile oils obtained atom has already been replaced by a radical, the by distillation; but some contain camphor-like second radical will take a position "meta" to substances, such as turpentine; others are bitter the first one, provided the first was COOH, like tansy; still others contain an odorous resin, SO:H, NO., or (probably) CN, CHO, or for example, myrrh and benzoin; and lastly CO.CH3. In most other cases the second radical there are those with a musky odor, such as the will mainly take the "para" position, though musk plant (q.v.). Among aromatics and some of the ortho” compound is almost in- the families to which they belong are: peppermint, variably produced at the same time. The aro- thyme, lavender, of the Labiata — the whole matic bodies include many acids, the simpler of plant, especially the leaves; caraway, dill, anise. which may be conveniently classified according of the Umbellifera — the seeds or seed capsules; to the number of molecules of carboxyl ginger, Zingiberacea—the root-stocks; cinnamon, (COOH) that they contain, and according to cassia, of the Lauracea Myrtacea — the bark; the number of hydrogen atoms that have been cloves, Myrtacea - the Aower buds; and vadisplaced in the original benzene ring. The nilla, of the Orchidacea - the fruits.

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