CRYSTALLOGRAPHY.

the substance. Hence, only elementary chemical substances and definite chemical compounds form crystals. The molecular structure by which crystal shapes are conditioned is not supposed, however, to be that of the chemical molecule, but a molecular grouping of a larger order involving a number of such chemical molecules. Crystals are formed either where a molten mass solidifies by cooling, or when the amount of a substance dissolved exceeds in quantity the amount which the solvent can retain in solution under the conditions obtaining. Hence, when a solution is evaporated until supersaturated, crystals of the dissolved substance are thrown down. Solutions show, however, considerable inertness, and it is often necessary to introduce some solid substance-best of all, a crystal of the substanceinto the solution, in order to start the process of crystallization. Exceptionally, crystals form directly from vapors, as in the cases of iodine and chloride of ammonia.

A substance which never forms crystals is said to be amorphous. A substance which possesses the regular molecular structure characteristic of crystals without the development of crystal faces is said to be crystalline. This condition often exists because crystals are crowded by their neighbors. The clearest proof that the regular structure is present, even when the faces are not developed, is furnished by an examination of the physical properties of the substance, for in a crystalline substance these have different values (or coefficients) for the different directions, and these values are in accord with the symmetry of the crystal faces when they are allowed to develop. For example, a sphere cut from a crystal of quartz does not, when heated, remain spherical, as would a piece of amorphous glass, but becomes distorted into a spheroid. This is due to the fact that the coefficient of expansion of the quartz is different in different directions, but is distributed with a symmetry in accord with, though somewhat different from, that of the crystal's shape.

CRYSTAL FACES AND ANGLES. On every single, or individual, crystal the dihedral or interfacial angles formed by the faces are never reëntrant. Moreover, the faces of a crystal are usually of several kinds or classes, and those which are alike, or of the same kind, are said to comprise a crystal form.' Faces belonging in the same form, unless perfectly smooth, have similar natural markings. The angles between faces of the same kind are identical in value. The instrument used in measuring crystal angles is called a goniometer (q.v.). Not only are the angles between the similar faces of a crystal constant in value, but in crystals of the same substance, no matter where found or how produced, they are of constant value, provided only the substance is pure and the measurements are made at the same temperature. Crystal angles are, therefore, individual and characteristic for each substance, and substances may be identified by measurement of their angles. Although the angles are characteristic and definite in size in crystals of the same substance, the size and relative developments of the faces themselves may vary between the widest limits, since these depend upon the accidents of growth (the feeding of crystal substances to the enlarging crystal) and not upon the crystal's characteristic structure the cause is external, not internal. Crystal

CRYSTALLOGRAPHY.

faces are, therefore, described in terms of their direction only, not of their absolute position in space. The groups of faces or forms which occur upon crystals of a single substance are found to have the same kind of symmetry, though as between crystals of different substances the symmetry may be quite different. Nearly all crystals have a centre of symmetry and one or more planes and axes of symmetry.

CRYSTAL CLASSES. No less than thirty-two crystal classes are called for by the mathematical theory which is based on the study of the properties of crystals. The edifice of crystal knowledge is one of the best founded in theory of any in the realm of physical science. Believing the origin of crystal structure and shape to lie in the grouping of the molecules, crystallographers set themselves the task of determining how many arrangements of points in space were possible if certain assumptions were made in accordance with properties known to be common to all crystals. It was found that thirty-two, and only that number, were possible, and, as regarded their symmetry, twenty-three corresponded exactly to the twenty-three kinds of crystal symmetry then known. It is the best possible proof of the general correctness of the theory that in the next eight years representatives were discovered among crystals of six of the nine remaining classes of crystal structure, and none were found not in correspondence with the classification. The thirty-two classes, known or possible, of crystal symmetry fall into six larger groups called 'crystal systems,' though some authors prefer to subdivide one of the systems, making the number seven. Crystal faces being described and named in terms of their directions, i.e. the relative intercepts which they make upon a system of coördinate axes, crystal systems are determined by the kinds of coördinate axes which are suited to the symmetry and which will allow of the simplest calculations. The six systems are known as (1) triclinic, which includes two classes; (2) monoclinic, which includes three classes; (3) orthorhombic, which includes three classes; (4) tetragonal, with seven classes; (5) hexagonal, with two divisions

the trigonal, seven classes; and hexagonal, five classes; and (6) isometric, which has five classes.

MODIFICATIONS. If the faces on a crystal could make any angle with the coördinate axes-any relative intercept whatsoever-the description of forms and faces would be attended with the greatest difficulty. Fortunately, however, there is found to be a law of crystals known as the law of rational indices, which greatly limits the number of possible faces. This law, while empirical, finds a ready explanation in the accepted theory of regular molecular structure. Chemical replacement processes bring about change in the composition in a substance without giving opportunity of readjustment of crystal forms. Thus, substances are found to occur in forms characteristic of other substances. These false forms are known as 'pseudomorphs.' Many chemical compounds have been observed in more than one kind of crystals. Such bodies are said to be dimorphous, trimorphous, or polymorphous. It is a law, however, that for each chemical compound there is a definite kind of crystal determined by its substance, and when two or more varieties of crystal are found, it indicates that two kinds of substances exist, which chemists

have not distinguished (isomerism). Similarity in chemical composition of substances is apt to be attended with similarity of crystal form, a relationship described as isomorphism (q.v.). Two or more crystal individuals of the same kind when grown together and partially parallel are known as twin crystals.

A

TWIN CRYSTALS.

A, E, Isometric system; B, Trigonal system; C, Tetragonal system; D, F, Orthorhombic system.

DIVISIONS OF CRYSTALLOGRAPHY. Crystallography is treated under the separate divisions of morphological crystallography, which concerns itself with external forms of crystals; crystallogeny or chemical crystallography, which has to do with the genesis or growth of crystals; and physical crystallography, which is concerned with the physical properties of crystals. Included in this latter division of the subject is optical crystallography, the application of which to mineralogical investigation laid the foundation for the modern science of petrology (q.v.) or petrography.

Consult: Dana, Text-book of Mineralogy, parts i.-iii (New York, 1898); Groth, Physikalische Krystallographie (Leipzig, 1895); Moses and Parsons, Elements of Mineralogy, Crystallography, and Blowpipe Analysis (New York, 1905). See MINERALOGY.

CRYSTALLOIDS (Gk. крvσrahhoɛidhs, krystalloeides, like crystal, from крúσтahhoç, krystallos, crystal eidos, eidos, form). Crystals of reserve proteids in plants. They occur in small proteid granules (see ALEURONE), in the endosperm (the food-bearing tissue surrounding the embyro), and in the embyro of various seeds. Similar crystals are found free in the outer cells of potato-tubers and in certain seaweeds. Crystalloids are angular in form, but their faces and angles are inconstant. They are insoluble in water, but absorb it and swell, as ordinary mineral crystals do not. They are insoluble in weak solutions but dissolve in strong solutions of common salt. The proteid material composing crystalloids belongs to the group of globulins. See also COLLOIDS.

CRYSTALLOMANCY (from Gk. крúoтaλoç, krystallos, crystal + pavreía, manteia, divination). At one time a popular practice of divination accomplished by means of transparent bodies. A transparent jewel was employed, but a beryl was deemed most effective. The operator first muttered over it certain formulas of prayer and then gave it into the hands of a youth or

virgin-none others were pure enough to discern its revelations-who read in it the information required. The desired facts were conveyed by means of written characters on the crystal, but sometimes the spirits invoked were supposed to appear in the crystal to answer the questions asked. This method of divination is still practiced by magicians. Consult Shorthouse, John Inglesant (London, 1881); Thomas, Crystal Gaz ing: Its History and Practice (New York, 1905).

CRYSTAL PALACE (so called because made of glass). An edifice erected in Hyde Park, London, for the World's Fair held in 1851. Designed by Sir Joseph Paxton, it was built of glass and iron, with floors of wood. Its length was 1608 feet and its area 21 acres. It cost £1,450,000. Every department of art and science was represented, and the visitors numbered over 6,000,000. Its materials were removed in 1854, and the structure rebuilt at Sydenham, eight miles from London. There the park and grounds cover nearly 200 acres, and a permanent fair is held. In 1853 a similar but smaller 'crystal palace' was erected between Fortieth and Fortysecond streets on Sixth Avenue, New York. It was used for exhibitions and grand concerts, but was destroyed by fire in 1858. The locality is now Bryant Park.

CSABA, chỡ bỏ, or BÉKÉS - CSABA, bā’kâsh-cho'bo, a town of Hungary, in the County of Békés, situated in a fertile district about five miles from the White Körös, with which it is connected by canal, and 122 miles east-southeast of Budapest (Map: Hungary, G 3). Its industries are principally agricultural, and cattleraising, wine production, and wheat and hemp growing. The women are noted for their skill in making linen and hemp fabrics. Csaba has the largest Protestant community of any town in Hungary, excepting Budapest. Population, in 1890, 32,244, of whom less than a fourth were Hungarians, and the rest Slavs; in 1900, 37,547.

CSÁNYI, chä'nyê, LÁSZLÓ (LADISLAS) (17901849). An Hungarian statesman. He was born at Csány (County of Zala), and served in the campaigns of 1809-15. He early manifested an interest in local politics, and became intimate with Francis Deák. In 1848 he was appointed commissioner plenipotentiary to various divisions of the Revolutionary army, and subsequently received from Kossuth a portfolio in the Ministry. After the surrender of the Hungarian army at Világos he refused to avail himself of the opportunity for flight; but as he had previously been one of the most active organizers of the revolution, so he now became a martyr to his convictions, and after a voluntary surrender to the Russians at Sarkad, he was delivered by them to the Austrians, and executed on October 10, 1849.

CSÁRDÁS, chär'däsh (Hung., from csárda, tavern). The national dance of Hungary. It consists of two movements, the first a slow lassu in lied form and in four-fourth or twofourth time. It is mostly in the minor mode. The second movement, friss or frischka, is an exceedingly lively dance also in four-fourth or two-fourth time. It is in the major mode and consists of eight and sixteen bar phrases, which are repeated. Toward the end the time is greatly accelerated and the rhythm becomes

CSÁRDÁS.

more and more complex, so that the whole piece has a wild, tumultuous, and abrupt character. In both parts of the csárdás the accent comes on the weak beat. The alternation from the lassu to the friss is made according to the will of the dancer, who motions to the players whenever he wants the change made. The figures of the csárdás vary greatly in different districts. The usual form opens with a stately promenade, which changes into a rapid whirling motion; the dancers then separate and carry on a sort of pantomime, the girl sometimes approaching, then retreating from her partner, who follows and finally seizes her. Again they whirl wildly around, then separate and go through much the same performance. The dance may be performed by any number of couples, but as no two couples are ever dancing identically the same figures at the same time, the whole gives a varied and complex appearance. See MAGYAR MUSIC.

CSENGERY, chěn'ge-ri, ANTON (1822-80). An Hungarian statesman and publicist. He was born at Grosswardein and early devoted himself to journalism. After editing the Pesti Hirlap for three years he was in 1848 appointed ministerial councilor, and followed the Hungarian Ministry to Debreczin. In 1849 he returned to Budapest and devoted himself to literary pursuits. In 1857 he founded the review entitled Budapesti Szemle, which he conducted for twelve years. He was an active promoter of agricultural and trade societies, and was one of the chief founders and afterwards the director of the Hungarian Institute of Land Credits. In 1861 he was elected to the Diet, where he became, as the most intimate friend of Deák, a powerful leader of the Deák party. In addition to his excellent translation of Macaulay's History of England (latest ed. 1874), he was the author of several important and brilliantly written works in Hungarian, among which may be mentioned: Historical Studies and Character Sketches (2 vols., 1870); History and Historians (1874); Memorial Address on Francis Deák (1877). His collected works were published in Budapest in 1884.

An

CSIKY, chê'kê, GERGELY (1842-91). Hungarian dramatist. He was born at Pankota (Arad), and after studying Catholic theology at Budapest and Vienna became professor at the Priests' Seminary in Temesvar. After an activity here of several years, he became a convert to Protestantism in 1878. Csiky is considered one of the greatest of modern Hungarian dramatists; he was equally effective in tragedy and comedy. He also wrote several successful novels and translated into Hungarian the works of Sophocles, Euripides, and Plautus, as well as standard works of French and English dramatists. Among his numerous plays, most of which have been highly successful, may be mentioned: The comedies Jóslat (The Oracle), Mukányi, and Kaviar; the tragedies Janus, Spartacus, Nora, and Theodora; and the popular drama The Proletarians.

CSOKONAI, cho'ko-no-ê, VITÉZ MIHÁLY (1773-1805). An Hungarian poet, born at Debreczin. He was appointed professor of poetry in the college at Debreczin in 1794, but resigned the post in 1795, in order to study law, and, with the exception of a brief connection with the gymnasium of Csurgo, he lived thenceforth in private, devoting himself wholly to literature. His

acquirements, particularly in linguistics, were notable. In poetry he was to some extent influenced by Földi, but remained essentially independent. He was preeminently a lyrist, in both the narrower domain of the folk-song and the larger realm of artistic poetry. His diction is simple and often naïve. Some pronounced defects of taste have met with the censure of the critics, but a distinguished place among modern Hungarian poets has been conceded to him. A collective edition of his works was published by Toldy in 1846. Two specimen poems rendered into German may be found in Schwicker, Geschichte der ungarischen Litteratur (Leipzig, 1889).

CSOMA DE KÖRÖS, chô'mỏ de kẽʼrẽsh, SánDOR (1784-1842). An Hungarian traveler and Tibetan scholar. He was born April 4, 1784, at Körös, in Transylvania, and was educated first at the college of Nagy-Enyed, and subsequently at Göttingen, where he devoted himself especially to the study of Oriental languages. It was the dream of his life to discover the original home of his race, the Magyars, in Asia. In 1820 he set out on his pilgrimage for that purpose. He went first to Teheran, then to Little Bokhara, and finally settled for four years (1827-30) at the Buddhist monastery of Kanam on the confines of Tibet and India, where he studied Tibetan. He found to his disappointment that the Tibetan language had little bearing on the Magyar problem, but it led him to Calcutta to study Sanskrit, as the literature of Tibet is largely translated from the Sanskrit. At Calcutta, where he became the object of general attention on the part of British scholars, he devoted himself to cataloguing the Tibetan books, upward of 1000 volumes, in the library of the Asiatic Society of Bengal. He prepared, likewise, a Tibetan grammar and dictionary (1834), which is still a standard work, and he wrote a number of articles on Tibetan literature in the Asiatic Researches. Once more he set out on his old-time search to find the early home of the Magyars, and bent his way toward the western confines of China, but while on this journey he died at Darjiling, northeastern India, April 11, 1842.

CSONGRÁD, chôn'gräd. A market-town of Hungary, in the county of the same name, situated on a point of land at the confluence of the Theiss and the Körös, 70 miles southeast of Budapest (Map: Hungary, G 3). The inhabitants are chiefly engaged in the rearing of cattle, fishing, and the cultivation of the vine. Population, in 1890, 20,802; in 1900, 22,619.

CTENACODON, tê-năk'ô-dōn. One of the rare primitive fossil mammals found in the Upper Jurassic rocks of Wyoming. It is known only by its lower jaw, which has a length of about one-half inch and indicates an animal of the size of a mouse. The teeth are of the multituberculate type, and consist of a prominent chiselshaped incisor, four longitudinally compressed premolars, which are distinctly cutting teeth with serrated edges and grooved sides, and of which the fourth is much the largest, and two small molars with tubercles surrounding the central cavities on their crowns. This type of dentition indicates relationship to the Monotremata (Ornithorhynchus and Echidna), which, together with the fossil Ctenacodon and its allies,