Chapter XXXIV: Part 34

CALAMY, EDMUND (1671-1732), English Nonconformist divine, the only son of Edmund Calamy "the younger," was born in London, in the parish of St Mary Aldermanbury, on the 5th of April 1671. He was sent to various schools, including Merchant Taylors', and in 1688 proceeded to the university of Utrecht. While there, he declined an offer of a professor's chair in the university of Edinburgh made to him by the principal, William Carstares, who had gone over on purpose to find suitable men for such posts. After his return to England in 1691 he began to study divinity, and on Baxter's advice went to Oxford, where he was much influenced by Chillingworth. He declined invitations from Andover and Bristol, and accepted one as assistant to Matthew Sylvester at Blackfriars (1692). In June 1694 he was publicly ordained at Annesley's meeting-house in Little St Helen's, and soon afterwards was invited to become assistant to Daniel Williams in Hand Alley, Bishopsgate. In 1702 he was chosen one of the lecturers in Salters' Hall, and in 1703 he succeeded Vincent Alsop as pastor of a large congregation in Westminster. In 1709 Calamy made a tour through Scotland, and had the degree of doctor of divinity conferred on him by the universities of Edinburgh, Aberdeen and Glasgow. Calamy's forty-one publications are mainly sermons, but his fame rests on his nonconformist biographies. His first essay was a table of contents to Baxter's _Narrative_ of his life and times, which was sent to the press in 1696; he made some remarks on the work itself and added to it an index, and, reflecting on the usefulness of the book, he saw the expediency of continuing it, as Baxter's history came no further than the year 1684. Accordingly, he composed an abridgment of it, with an account of many other ministers who were ejected after the restoration of Charles II.; their apology, containing the grounds of their nonconformity and practice as to stated and occasional communion with the Church of England; and a continuation of their history until the year 1691. This work was published in 1702. The most important chapter (ix.) is that which gives a detailed account of the ministers ejected in 1662; it was afterwards published as a distinct volume. He afterwards published a moderate defence of Nonconformity, in three tracts, in answer to some tracts of Benjamin, afterwards Bishop, Hoadly. In 1713 he published a second edition (2 vols.) of his _Abridgment of Baxter's History_, in which, among various additions, there is a continuation of the history through the reigns of William and Anne, down to the passing of the Occasional Bill. At the end is subjoined the reformed liturgy, which was drawn up and presented to the bishops in 1661. In 1718 he wrote a vindication of his grandfather and several other persons against certain reflections cast upon them by Laurence Echard in his _History of England_. In 1719 he published _The Church and the Dissenters Compar'd as to Persecution_, and in 1728 appeared his _Continuation of the Account_ of the ejected ministers and teachers, a volume which is really a series of emendations of the previously published account. He died on the 3rd of June 1732, having been married twice and leaving six of his thirteen children to survive him. Calamy was a kindly man, frankly self-conscious, but very free from jealousy. He was an able diplomatist and generally secured his ends. His great hero was Baxter, of whom he wrote three distinct memoirs. His eldest son Edmund (the fourth) was a Presbyterian minister in London and died 1755; another son (Edmund, the fifth) was a barrister who died in 1816; and this one's son (Edmund, the sixth) died in 1850, his younger brother Michael, the last of the direct Calamy line, surviving till 1876.

CALARASHI (_C[)a]l[)a]rasi_), the capital of the Jalomitza department, Rumania, situated on the left bank of the Borcea branch of the Danube, amid wide fens, north of which extends the desolate Baragan Steppe. Pop. (1900) 11,024. Calarashi has a considerable transit trade in wheat, linseed, hemp, timber and fish from a broad mere on the west or from the Danube. Small vessels carry cargo to Braila and Galatz, and a branch railway from Calarashi traverses the Steppe from south to north, and meets the main line between Bucharest and Constantza.

CALAS, JEAN (1698-1762), a Protestant merchant at Toulouse, whose legal murder is a celebrated case in French history. His wife was an Englishwoman of French extraction. They had three sons and three daughters. His son Louis had embraced the Roman Catholic faith through the persuasions of a female domestic who had lived thirty years in the family. In October 1761 another son, Antoine, hanged himself in his father's warehouse. The crowd, which collected on so shocking a discovery, took up the idea that he had been strangled by the family to prevent him from changing his religion, and that this was a common practice among Protestants. The officers of justice adopted the popular tale, and were supplied by the mob with what they accepted as conclusive evidence of the fact. The fraternity of White Penitents buried the body with great ceremony, and performed a solemn service for the deceased as a martyr; the Franciscans followed their example; and these formalities led to the popular belief in the guilt of the unhappy family. Being all condemned to the rack in order to extort confession, they appealed to the parlement; but this body, being as weak as the subordinate magistrates, sentenced the father to the torture, ordinary and extraordinary, to be broken alive upon the wheel, and then to be burnt to ashes; which decree was carried into execution on the 9th of March 1762. Pierre Calas, the surviving son, was banished for life; the rest were acquitted. The distracted widow, however, found some friends, and among them Voltaire, who laid her case before the council of state at [v.04 p.0968] Versailles. For three years he worked indefatigably to procure justice, and made the Calas case famous throughout Europe (see VOLTAIRE). Finally the king and council unanimously agreed to annul the proceeding of the parlement of Toulouse; Calas was declared to have been innocent, and every imputation of guilt was removed from the family.

See _Causes célèbres_, tome iv.; Raoul Allier, _Voltaire et Calas, une erreur judiciaire au XVIII^e siècle_ (Paris, 1898); and biographies of Voltaire.

CALASH (from Fr. _calèche_, derived from Polish _kolaska_, a wheeled carriage), a light carriage with a folding hood; the Canadian calash is two-wheeled and has a seat for the driver on the splash-board. The word is also used for a kind of hood made of silk stretched over hoops, formerly worn by women.

CALASIAO, a town of the province of Pangasinán, Luzon, Philippine Islands, on a branch of the Agno river, about 4 m. S. by E. of Dagupan, the N. terminal of the Manila & Dagupan railway. Pop. (1903) 16,539. In 1903, after the census had been taken, the neighbouring town of Santa Barbara (pop. 10,367) was annexed to Calasiao. It is in the midst of a fertile district and has manufactures of hats and various woven fabrics.

CALASIO, MARIO DI (1550-1620), Italian Minorite friar, was born at a small town in the Abruzzi whence he took his name. Joining the Franciscans at an early age, he devoted himself to Oriental languages and became an authority on Hebrew. Coming to Rome he was appointed by Paul V., whose confessor he was, to the chair of Scripture at Ara Coeli, where he died on the 1st of February 1620. Calasio is known by his _Concordantiae sacrorum Bibliorum hebraicorum_, published in 4 vols. (Rome, 1622), two years after his death, a work which is based on Nathan's _Hebrew Concordance_ (Venice, 1523). For forty years Calasio laboured on this work, and he secured the assistance of the greatest scholars of his age. The _Concordance_ evinces great care and accuracy. All root-words are treated in alphabetical order and the whole Bible has been collated for every passage containing the word, so as to explain the original idea, which is illustrated from the cognate usages of the Chaldee, Syrian, Rabbinical Hebrew and Arabic. Calasio gives under each Hebrew word the literal Latin translation, and notes any existing differences from the Vulgate and Septuagint readings. An incomplete English translation of the work was published in London by Romaine in 1747. Calasio also wrote a Hebrew grammar, _Canones generates linguae sanctatae_ (Rome, 1616), and the _Dictionarium hebraicum_ (Rome, 1617).

CALATAFIMI, a town of the province of Trapani, Sicily, 30 m. W.S.W. of Palermo direct (51½ m. by rail). Pop. (1901) 11,426. The name of the town is derived from the Saracenic castle of _Kalat-al-Fimi_ (castle of Euphemius), which stands above it. The principal church contains a fine Renaissance reredos in marble. Samuel Butler, the author of _Erewhon_, did much of his work here. The battlefield where Garibaldi won his first victory over the Neapolitans on the 15th of May 1860, lies 2 m. S.W.

CALATAYÚD, a town of central Spain, in the province of Saragossa, at the confluence of the rivers Jalón and Jiloca, and on the Madrid-Saragossa and Calatayúd-Sagunto railways. Pop. (1900) 11,526. Calatayúd consists of a lower town, built on the left bank of the Jalón, and an upper or Moorish town, which contains many dwellings hollowed out of the rock above and inhabited by the poorer classes. Among a number of ecclesiastical buildings, two collegiate churches are especially noteworthy. Santa Maria, originally a mosque, has a lofty octagonal tower and a fine Renaissance doorway, added in 1528; while Santo Sepulcro, built in 1141, and restored in 1613, was long the principal church of the Spanish Knights Templar. In commercial importance Calatayúd ranks second only to Saragossa among the Aragonese towns, for it is the central market of the exceptionally fertile expanse watered by the Jalón and Jiloca. About 2 m. E. are the ruins of the ancient _Bilbilis_, where the poet Martial was born c. A.D. 40. It was celebrated for its breed of horses, its armourers, its gold and its iron; but Martial also mentions its unhealthy climate, due to the icy winds which sweep down from the heights of Moncayo (7705 ft.) on the north. In the middle ages the ruins were almost destroyed to provide stone for the building of Calatayúd, which was founded by a Moorish amir named Ayub and named _Kalat Ayub_, "Castle of Ayub." Calatayúd was captured by Alphonso I. of Aragon in 1119.

CALATIA, an ancient town of Campania, Italy, 6 m. S.E. of Capua, on the Via Appia, near the point where the Via Popillia branches off from it. It is represented by the church of St. Giacomo alle Galazze. The Via Appia here, as at Capua, abandons its former S.E. direction for a length of 2000 Oscan ft. (1804½ English ft.), for which it runs due E. and then resumes its course S.E. There are no ruins, but a considerable quantity of débris; and the pre-Roman necropolis was partially excavated in 1882. Ten shafts lined with slabs of tufa which were there found may have been the approaches to tombs or may have served as wells. The history of Calatia is practically that of its more powerful neighbour Capua, but as it lay near the point where the Via Appia turns east and enters the mountains, it had some strategic importance. In 313 B.C. it was taken by the Samnites and recaptured by the dictator Q. Fabius; the Samnites captured it again in 311, but it must have been retaken at an unknown date. In the 3rd century we find it issuing coins with an Oscan legend, but in 211 B.C. it shared the fate of Capua. In 174 we hear of its walls being repaired by the censors. In 59 B.C. a colony was established here by Caesar.

See Ch. Hülsen in Pauly-Wissowa, _Realencyclopädie_, iii. 1334 (Stuttgart, 1899).

CALAVERAS SKULL, a famous fossil cranium, reported by Professor J.D. Whitney as found (1886) in the undisturbed auriferous gravels of Calaveras county, California. The discovery at once raised the still discussed question of "tertiary man" in the New World. Doubt has been thrown on the genuineness of the find, as the age of the gravels is disputed and the skull is of a type corresponding exactly with that of the present Indian inhabitants of the district. Whitney assigns the fossil to late Tertiary (Pliocene) times, and concludes that "man existed in California previous to the cessation of volcanic activity in the Sierra Nevada, to the epoch of the greatest extension of the glaciers in that region and to the erosion of the present river cañons and valleys, at a time when the animal and vegetable creation differed entirely from what they now are...." The specimen is preserved in the Peabody museum, Cambridge, Mass.

CALBÁYOG, a town of the province of Sámar, Philippine Islands, on the W. coast at the mouth of the Calbáyog river, about 30 m. N.W. of Catbalogan, the capital, in lat. 12° 3' N. Pop. (1903) 15,895. Calbáyog has an important export trade in hemp, which is shipped to Manila. Copra is also produced in considerable quantity, and there is fine timber in the vicinity. There are hot springs near the town. The neighbouring valleys of the Gándara and Hippatan rivers are exceedingly fertile, but in 1908 were uncultivated. The climate is very warm, but healthy. The language is Visayan.

CALBE, or KALBE, a town of Germany, on the Saale, in Prussian Saxony. It is known as Calbe-an-der-Saale, to distinguish it from the smaller town of Calbe on the Milde in the same province. Pop. (1905) 12,281. It is a railway junction, and among its industries are wool-weaving and the manufacture of cloth, paper, stoves, sugar and bricks. Cucumbers and onions are cultivated, and soft coal is mined in the neighbourhood.

CALCAR (or KALCKER), JOHN DE (1499-1546), Italian painter, was born at Calcar, in the duchy of Cleves. He was a disciple of Titian at Venice, and perfected himself by studying Raphael. He imitated those masters so closely as to deceive the most skilful critics. Among his various pieces is a Nativity, representing the angels around the infant Christ, which he arranged so that the light emanated wholly from the child. He died at Naples.

CALCEOLARIA, in botany, a genus belonging to the natural order Scrophulariaceae, containing about 150 species of herbaceous or shrubby plants, chiefly natives of the South American Andes of Peru and Chile. The calceolaria of the present day has [v.04 p.0969] been developed into a highly decorative plant, in which the herbaceous habit has preponderated. The plants are now very generally raised annually from seed, which is sown about the end of June in a mixture of loam, leaf-mould and sand, and, being very small, must be only slightly covered. When the plants are large enough to handle they are pricked out an inch or two apart into 3-inch or 5-inch pots; when a little more advanced they are potted singly. They should be wintered in a greenhouse with a night temperature of about 40°, occupying a shelf near the light. By the end of February they should be moved into 8-inch or 10-inch pots, using a compost of three parts good turfy loam, one part leaf-mould, and one part thoroughly rotten manure, with a fair addition of sand. They need plenty of light and air, but must not be subjected to draughts. When the pots get well filled with roots, they must be liberally supplied with manure water. In all stages of growth the plants are subject to the attacks of the green-fly, for which they must be fumigated.

The so-called shrubby calceolarias used for bedding are increased from cuttings, planted in autumn in cold frames, where they can be wintered, protected from frost by the use of mats and a good layer of litter placed over the glass and round the sides.

CALCHAQUI, a tribe of South American Indians, now extinct, who formerly occupied northern Argentina. Stone and other remains prove them to have reached a high degree of civilization. They offered a vigorous resistance to the first Spanish colonists coming from Chile.

CALCHAS, of Mycenae or Megara, son of Thestor, the most famous soothsayer among the Greeks at the time of the Trojan war. He foretold the duration of the siege of Troy, and, when the fleet was detained by adverse winds at Aulis, he explained the cause and demanded the sacrifice of Iphigeneia. When the Greeks were visited with pestilence on account of Chryseis, he disclosed the reasons of Apollo's anger. It was he who suggested that Neoptolemus and Philoctetes should be fetched from Scyros and Lemnos to Troy, and he was one of those who advised the construction of the wooden horse. When the Greeks, on their journey home after the fall of Troy, were overtaken by a storm, Calchas is said to have been thrown ashore at Colophon. According to another story, he foresaw the storm and did not attempt to return by sea. It had been predicted that he should die when he met his superior in divination; and the prophecy was fulfilled in the person of Mopsus, whom Calchas met in the grove of the Clarian Apollo near Colophon. Having been beaten in a trial of soothsaying, Calchas died of chagrin or committed suicide. He had a temple and oracle in Apulia.

Ovid, _Metam._ xii. 18 ff.; Homer, _Iliad_ i. 68, ii. 322; Strabo vi. p. 284, xiv. p. 642.

CALCITE, a mineral consisting of naturally occurring calcium carbonate, CaCO_3, crystallizing in the rhombohedral system. With the exception of quartz, it is the most widely distributed of minerals, whilst in the beautiful development and extraordinary variety of form of its crystals it is surpassed by none. In the massive condition it occurs as large rock-masses (marble, limestone, chalk) which are often of organic origin, being formed of the remains of molluscs, corals, crinoids, &c., the hard parts of which consist largely of calcite.

The name calcite (Lat. _calx_, _calcis_, meaning burnt lime) is of comparatively recent origin, and was first applied, in 1836, to the "barleycorn" pseudomorphs of calcium carbonate after celestite from Sangerhausen in Thuringia; it was not until about 1843 that the name was used in its present sense. The mineral had, however, long been known under the names calcareous spar and calc-spar, and the beautifully transparent variety called Iceland-spar had been much studied. The strong double refraction and perfect cleavages of Iceland-spar were described in detail by Erasmus Bartholinus in 1669 in his book _Experimenta Crystalli Islandici disdiaclastici_; the study of the same mineral led Christiaan Huygens to discover in 1690 the laws of double refraction, and E.L. Malus in 1808 the polarization of light.

An important property of calcite is the great ease with which it may be cleaved in three directions; the three perfect cleavages are parallel to the faces of the primitive rhombohedron, and the angle between them was determined by W.H. Wollaston in 1812, with the aid of his newly invented reflective goniometer, to be 74° 55'. The cleavage is of great help in distinguishing calcite from other minerals of similar appearance. The hardness of 3 (it is readily scratched with a knife), the specific gravity of 2.72, and the fact that it effervesces briskly in contact with cold dilute acids are also characters of determinative value.

Crystals of calcite are extremely varied in form, but, as a rule, they may be referred to four distinct habits, namely: rhombohedral, prismatic, scalenohedral and tabular. The primitive rhombohedron, r {100} (fig. 1), is comparatively rare except in combination with other forms. A flatter rhombohedron, e {110}, is shown in fig. 2, and a more acute one, f {11-1}, in fig. 3. These three rhombohedra are related in such a manner that, when in combination, the faces of r truncate the polar edges of f, and the faces of e truncate the edges of r. The crystal of prismatic habit shown in fig. 4 is a combination of the prism m {2-1-1} and the rhombohedron e {110}; fig. 5 is a combination of the scalenohedron v {20-1} and the rhombohedron r {100}; and the crystal of tabular habit represented in fig. 6 is a combination of the basal pinacoid c {111}, prism m {2-1-1}, and rhombohedron e {110}. In these figures only six distinct forms (r, e, f, m, v, c) are represented, but more than 400 have been recorded for calcite, whilst the combinations of them are almost endless.

Depending on the habits of the crystals, certain trivial names have been used, such, for example, as dog-tooth-spar for the crystals of scalenohedral habit, so common in the Derbyshire lead mines and limestone caverns; nail-head-spar for crystals terminated by the obtuse rhombohedron e, which are common in the lead mines of Alston Moor in Cumberland; slate-spar (German _Schieferspath_) for crystals of tabular habit, and sometimes as thin as paper: cannon-spar for crystals of prismatic habit terminated by the basal pinacoid c.

Calcite is also remarkable for the variety and perfection of its twinned crystals. Twinned crystals, though not of infrequent occurrence, are, however, far less common than simple (untwinned) crystals. No less than four well-defined twin-laws are to be distinguished:--

i. Twin-plane c (111).--Here there is rotation of one portion with respect to the other through 180° about the principal (trigonal) axis, which is perpendicular to the plane c (111); or the same result may be obtained by reflection across this plane. Fig. 7 shows a prismatic crystal (like fig. 4) twinned in this manner, and fig. 8 represents a twinned scalenohedron v {20-1}.

ii. Twin-plane e (110).--The principal axes of the two portions are inclined at an angle of 52° 30½'. Repeated twinning on this plane is very common, and the twin-lamellae (fig. 9) to which it gives rise are often to be observed in the grains of calcite of crystalline limestones which have been subjected to pressure. This lamellar twinning is of secondary origin; it may be readily produced artificially by pressure, for example, by pressing a knife into the edge of a cleavage rhombohedron.

[v.04 p.0970] iii. Twin-plane r (100).--Here the principal axes of the two portions are nearly at right angles (89° 14'), and one of the directions of cleavage in both portions is parallel to the twin-plane. Fine crystals of prismatic habit twinned according to this law were formerly found in considerable numbers at Wheal Wrey in Cornwall, and of scalenohedral habit at Eyam in Derbyshire and Cleator Moor in Cumberland; those from the last two localities are known as "butterfly twins" or "heart-shaped twins" (fig. 10), according to their shape.

iv. Twin-plane f (11-1).--The principal axes are here inclined at 53° 46'. This is the rarest twin-law of calcite.

Calcite when pure, as in the well-known Iceland-spar, is perfectly transparent and colourless. The lustre is vitreous. Owing to the presence of various impurities, the transparency and colour may vary considerably. Crystals are often nearly white or colourless, usually with a slight yellowish tinge. The yellowish colour is in most cases due to the presence of iron, but in some cases it has been proved to be due to organic matter (such as apocrenic acid) derived from the humus overlying the rocks in which the crystals were formed. An opaque calcite of a grass-green colour, occurring as large cleavage masses in central India and known as hislopite, owes its colour to enclosed "green-earth" (glauconite and celadonite). A stalagmitic calcite of a beautiful purple colour, from Reichelsdorf in Hesse, is coloured by cobalt.

Optically, calcite is uniaxial with negative bi-refringence, the index of refraction for the ordinary ray being greater than for the extraordinary ray; for sodium-light the former is 1.6585 and the latter 1.4862. The difference, 0.1723, between these two indices gives a measure of the bi-refringence or double refraction.

Although the double refraction of some other minerals is greater than that of calcite (_e.g._ for cinnabar it is 0.347, and for calomel 0.683), yet this phenomenon can be best demonstrated in calcite, since it is a mineral obtainable in large pieces of perfect transparency. Owing to the strong double refraction and the consequent wide separation of the two polarized rays of light traversing the crystal, an object viewed through a cleavage rhombohedron of Iceland-spar is seen double, hence the name doubly-refracting spar. Iceland-spar is extensively used in the construction of Nicol's prisms for polariscopes, polarizing microscopes and saccharimeters, and of dichroscopes for testing the pleochroism of gem-stones.

Chemically, calcite has the same composition as the orthorhombic aragonite (_q.v._), these minerals being dimorphous forms of calcium carbonate. Well-crystallized material, such as Iceland-spar, usually consists of perfectly pure calcium carbonate, but at other times the calcium may be isomorphously replaced by small amounts of magnesium, barium, strontium, manganese, zinc or lead. When the elements named are present in large amount we have the varieties dolomitic calcite, baricalcite, strontianocalcite, ferrocalcite, manganocalcite, zincocalcite and plumbocalcite, respectively.

Mechanically enclosed impurities are also frequently present, and it is to these that the colour is often due. A remarkable case of enclosed impurities is presented by the so-called Fontainbleau limestone, which consists of crystals of calcite of an acute rhombohedral form (fig. 3) enclosing 50 to 60% of quartz-sand. Similar crystals, but with the form of an acute hexagonal pyramid, and enclosing 64% of sand, have recently been found in large quantity over a wide area in South Dakota, Nebraska and Wyoming. The case of hislopite, which encloses up to 20% of "green earth," has been noted above.

In addition to the varieties of calcite noted above, some others, depending on the state of aggregation of the material, are distinguished. A finely fibrous form is known as satin-spar (_q.v._), a name also applied to fibrous gypsum: the most typical example of this is the snow-white material, often with a rosy tinge and a pronounced silky lustre, which occurs in veins in the Carboniferous shales of Alston Moor in Cumberland. Finely scaly varieties with a pearly lustre are known as argentine and aphrite (German _Schaumspath_); soft, earthy and dull white varieties as agaric mineral, rock-milk, rock-meal, &c.--these form a transition to marls, chalk, &c. Of the granular and compact forms numerous varieties are distinguished (see LIMESTONE and MARBLE). In the form of stalactites calcite is of extremely common occurrence. Each stalactite usually consists of an aggregate of radially arranged crystalline individuals, though sometimes it may consist of a single individual with crystal faces developed at the free end. Onyx-marbles or Oriental alabaster (see ALABASTER) and other stalagmitic deposits also consist of calcite, and so do the allied deposits of travertine, calc-sinter or calc-tufa.

The modes of occurrence of calcite are very varied. It is a common gangue mineral in metalliferous deposits, and in the form of crystals is often associated with ores of lead, iron, copper and silver. It is a common product of alteration in igneous rocks, and frequently occurs as well-developed crystals in association with zeolites lining the amygdaloidal cavities of basaltic and other rocks. Veins and cavities in limestones are usually lined with crystals of calcite. The wide distribution, under various conditions, of crystallized calcite is readily explained by the solubility of calcium carbonate in water containing carbon dioxide, and the ease with which the material is again deposited in the crystallized state when the carbon dioxide is liberated by evaporation. On this also depends the formation of stalactites and calc-sinter.

Localities at which beautifully crystallized specimens of calcite are found are extremely numerous. For beauty of crystals and variety of forms the haematite mines of the Cleator Moor district in west Cumberland and the Furness district in north Lancashire are unsurpassed. The lead mines of Alston in Cumberland and of Derbyshire, and the silver mines of Andreasberg in the Harz and Guanajuato in Mexico have yielded many fine specimens. From the zinc mines of Joplin in Missouri enormous crystals of golden-yellow and amethystine colours have been recently obtained. At all the localities here mentioned the crystals occur with metalliferous ores. In Iceland the mode of occurrence is quite distinct, the mineral being here found in a cavity in basalt.

The quarry, which since the 19th century has supplied the famous Iceland-spar, is in a cavity in basalt, the cavity itself measuring 12 by 5 yds. in area and about 10 ft. in height. It is situated quite close to the farm Helgustadir, about an hour's ride from the trading station of Eskifjordur on Reydar Fjordur, on the east coast of Iceland. This cavity when first found was filled with pure crystallized masses and enormous crystals. The crystals measure up to a yard across, and are rhombohedral or scalenohedral in habit; their faces are usually dull and corroded or coated with stilbite. In recent years much of the material taken out has not been of sufficient transparency for optical purposes, and this, together with the very limited supply, has caused a considerable rise in price. Only very occasionally has calcite from any locality other than Iceland been used for the construction of a Nicol's prism.

(L. J. S.)

CALCIUM [symbol Ca, atomic weight 40.0 (O=16)], a metallic chemical element, so named by Sir Humphry Davy from its [v.04 p.0971] occurrence in chalk (Latin _calx_). It does not occur in nature in the free state, but in combination it is widely and abundantly diffused. Thus the sulphate constitutes the minerals anhydrite, alabaster, gypsum, and selenite; the carbonate occurs dissolved in most natural waters and as the minerals chalk, marble, calcite, aragonite; also in the double carbonates such as dolomite, bromlite, barytocalcite; the fluoride as fluorspar; the fluophosphate constitutes the mineral apatite; while all the more important mineral silicates contain a proportion of this element.

_Extraction._--Calcium oxide or lime has been known from a very remote period, and was for a long time considered to be an elementary or undecomposable earth. This view was questioned in the 18th century, and in 1808 Sir Humphry Davy (_Phil. Trans._, 1808, p. 303) was able to show that lime was a combination of a metal and oxygen. His attempts at isolating this metal were not completely successful; in fact, metallic calcium remained a laboratory curiosity until the beginning of the 20th century. Davy, inspired by his successful isolation of the metals sodium and potassium by the electrolysis of their hydrates, attempted to decompose a mixture of lime and mercuric oxide by the electric current; an amalgam of calcium was obtained, but the separation of the mercury was so difficult that even Davy himself was not sure as to whether he had obtained pure metallic calcium. Electrolysis of lime or calcium chloride in contact with mercury gave similar results. Bunsen (_Ann._, 1854, 92, p. 248) was more successful when he electrolysed calcium chloride moistened with hydrochloric acid; and A. Matthiessen (_Jour. Chem. Soc._, 1856, p. 28) obtained the metal by electrolysing a mixture of fused calcium and sodium chlorides. Henri Moissan obtained the metal of 99% purity by electrolysing calcium iodide at a low red heat, using a nickel cathode and a graphite anode; he also showed that a more convenient process consisted in heating the iodide with an excess of sodium, forming an amalgam of the product, and removing the sodium by means of absolute alcohol (which has but little action on calcium), and the mercury by distillation.

The electrolytic isolation of calcium has been carefully investigated, and this is the method followed for the commercial production of the metal. In 1902 W. Borchers and L. Stockem (_Zeit. für Electrochemie_, 1902, p. 8757) obtained the metal of 90% purity by electrolysing calcium chloride at a temperature of about 780°, using an iron cathode, the anode being the graphite vessel in which the electrolysis was carried out. In the same year, O. Ruff and W. Plato (_Ber._ 1902, 35, p. 3612) employed a mixture of calcium chloride (100 parts) and fluorspar (16.5 parts), which was fused in a porcelain crucible and electrolysed with a carbon anode and an iron cathode. Neither of these processes admitted of commercial application, but by a modification of Ruff and Plato's process, W. Ruthenau and C. Suter have made the metal commercially available. These chemists electrolyse either pure calcium chloride, or a mixture of this salt with fluorspar, in a graphite vessel which serves as the anode. The cathode consists of an iron rod which can be gradually raised. On electrolysis a layer of metallic calcium is formed at the lower end of this rod on the surface of the electrolyte; the rod is gradually raised, the thickness of the layer increases, and ultimately a rod of metallic calcium, forming, as it were, a continuation of the iron cathode, is obtained. This is the form in which calcium is put on the market.

An idea as to the advance made by this method is recorded in the variation in the price of calcium. At the beginning of 1904 it was quoted at 5s. per gram, £250 per kilogram or £110 per pound; about a year later the price was reduced to 21s. per kilogram, or 12s. per kilogram in quantities of 100 kilograms. These quotations apply to Germany; in the United Kingdom the price (1905) varied from 27s. to 30s. per kilogram (12s. to 13s. per lb.).

_Properties._--A freshly prepared surface of the metal closely resembles zinc in appearance, but on exposure to the air it rapidly tarnishes, becoming yellowish and ultimately grey or white in colour owing to the information of a surface layer of calcium hydrate. A faint smell of acetylene may be perceived during the oxidation in moist air; this is probably due to traces of calcium carbide. It is rapidly acted on by water, especially if means are taken to remove the layer of calcium hydrate formed on the metal; alcohol acts very slowly. In its chemical properties it closely resembles barium and strontium, and to some degree magnesium; these four elements comprise the so-called metals of the "alkaline earths." It combines directly with most elements, including nitrogen; this can be taken advantage of in forming almost a perfect vacuum, the oxygen combining to form the oxide, CaO, and the nitrogen to form the nitride, Ca_3N_2. Several of its physical properties have been determined by K. Arndt (_Ber._, 1904, 37, p. 4733). The metal as prepared by electrolysis generally contains traces of aluminium and silica. Its specific gravity is 1.54, and after remelting 1.56; after distillation it is 1.52. It melts at about 800°, but sublimes at a lower temperature.

_Compounds._--Calcium hydride, obtained by heating electrolytic calcium in a current of hydrogen, appears in commerce under the name hydrolite. Water decomposes it to give hydrogen free from ammonia and acetylene, 1 gram yielding about 100 ccs. of gas (Prats Aymerich, _Abst. J.C.S._, 1907, ii p. 460). Calcium forms two oxides--the monoxide, CaO, and the dioxide, CaO_2. The monoxide and its hydrate are more familiarly known as lime (_q.v._) and slaked-lime. The dioxide was obtained as the hydrate, CaO_2·8H_2O, by P. Thénard (_Ann. Chim. Phys._, 1818, 8, p. 213), who precipitated lime-water with hydrogen peroxide. It is permanent when dry; on heating to 130° C. it loses water and gives the anhydrous dioxide as an unstable, pale buff-coloured powder, very sparingly soluble in water. It is used as an antiseptic and oxidizing agent.

Whereas calcium chloride, bromide, and iodide are deliquescent solids, the fluoride is practically insoluble in water; this is a parallelism to the soluble silver fluoride, and the insoluble chloride, bromide and iodide. _Calcium fluoride_, CaF_2, constitutes the mineral fluor-spar (_q.v._), and is prepared artificially as an insoluble white powder by precipitating a solution of calcium chloride with a soluble fluoride. One part dissolves in 26,000 parts of water. _Calcium chloride_, CaCl_2, occurs in many natural waters, and as a by-product in the manufacture of carbonic acid (carbon dioxide), and potassium chlorate. Aqueous solutions deposit crystals containing 2, 4 or 6 molecules of water. Anhydrous calcium chloride, prepared by heating the hydrate to 200° (preferably in a current of hydrochloric acid gas, which prevents the formation of any oxychloride), is very hygroscopic, and is used as a desiccating agent. It fuses at 723°. It combines with gaseous ammonia and forms crystalline compounds with certain alcohols. The crystallized salt dissolves very readily in water with a considerable absorption of heat; hence its use in forming "freezing mixtures." A temperature of -55°C. is obtained by mixing 10 parts of the hexahydrate with 7 parts of snow. A saturated solution of calcium chloride contains 325 parts of CaCl_2 to 100 of water at the boiling point (179.5°). Calcium iodide and bromide are white deliquescent solids and closely resemble the chloride.

_Chloride of lime_ or "bleaching powder" is a calcium chlor-hypochlorite or an equimolecular mixture of the chloride and hypochlorite (see ALKALI MANUFACTURE and BLEACHING).

_Calcium carbide_, CaC_2, a compound of great industrial importance as a source of acetylene, was first prepared by F. Wohler. It is now manufactured by heating lime and carbon in the electric furnace (see ACETYLENE). Heated in chlorine or with bromine, it yields carbon and calcium chloride or bromide; at a dull red heat it burns in oxygen, forming calcium carbonate, and it becomes incandescent in sulphur vapour at 500°, forming calcium sulphide and carbon disulphide. Heated in the electric furnace in a current of air, it yields calcium cyanamide (see CYANAMIDE).

_Calcium carbonate_, CaCO_3, is of exceptionally wide distribution in both the mineral and animal kingdoms. It constitutes the bulk of the chalk deposits and limestone rocks; it forms over one-half of the mineral dolomite and the rock magnesium limestone; it occurs also as the dimorphous minerals aragonite (_q.v._) and calcite (_q.v._). Tuff (_q.v._) and travertine are calcareous deposits found in volcanic districts. Most natural waters contain it dissolved in carbonic acid; this confers "temporary hardness" on the water. The dissipation of the dissolved carbon dioxide results in the formation of "fur" in kettles or boilers, and if the solution is falling, as from the roof of a cave, in the formation of stalactites and stalagmites. In the animal kingdom it occurs as both calcite and aragonite in the tests of the foraminifera, echinoderms, brachiopoda, and mollusca; also in the skeletons of sponges and corals. Calcium carbonate is obtained as a white precipitate, almost insoluble in water (1 part requiring 10,000 of water for solution), by mixing solutions of a carbonate and a calcium salt. Hot or dilute cold solutions deposit minute orthorhombic crystals of aragonite, cold saturated or moderately strong solutions, hexagonal (rhombohedral) crystals of calcite. Aragonite is the least stable form; crystals have been found altered to calcite.

_Calcium nitride_, Ca_3N_2, is a greyish-yellow powder formed by heating calcium in air or nitrogen; water decomposes it with evolution of ammonia (see H. Moissan, _Compt. Rend._, 127, p. 497).

_Calcium nitrate_, Ca(NO_3)_2·4H_2O, is a highly deliquescent salt, [v.04 p.0972] crystallizing in monoclinic prisms, and occurring in various natural waters, as an efflorescence in limestone caverns, and in the neighbourhood of decaying nitrogenous organic matter. Hence its synonyms, "wall-saltpetre" and "lime-saltpetre"; from its disintegrating action on mortar, it is sometimes referred to as "saltpetre rot." The anhydrous nitrate, obtained by heating the crystallized salt, is very phosphorescent, and constitutes "Baldwin's phosphorus." A basic nitrate, Ca(NO_3)_2·Ca(OH)_2·3H_2O, is obtained by dissolving calcium hydroxide in a solution of the normal nitrate.

_Calcium phosphide_, Ca_3P_2, is obtained as a reddish substance by passing phosphorus vapour over strongly heated lime. Water decomposes it with the evolution of spontaneously inflammable hydrogen phosphide; hence its use as a marine signal fire ("Holmes lights"), (see L. Gattermann and W. Haussknecht, _Ber._, 1890, 23, p. 1176, and H. Moissan, _Compt. Rend._, 128, p. 787).

Of the calcium orthophosphates, the normal salt, Ca_3(PO_4)_2, is the most important. It is the principal inorganic constituent of bones, and hence of the "bone-ash" of commerce (see PHOSPHORUS); it occurs with fluorides in the mineral apatite (_q.v._); and the concretions known as coprolites (_q.v._) largely consist of this salt. It also constitutes the minerals ornithite, Ca_3(PO_4)_2·2H_2O, osteolite and sombrerite. The mineral brushite, CaHPO_4·2H_2O, which is isomorphous with the acid arsenate pharmacolite, CaHAsO_4·2H_2O, is an acid phosphate, and assumes monoclinic forms. The normal salt may be obtained artificially, as a white gelatinous precipitate which shrinks greatly on drying, by mixing solutions of sodium hydrogen phosphate, ammonia, and calcium chloride. Crystals may be obtained by heating di-calcium pyrophosphate, Ca_2P_2O_7, with water under pressure. It is insoluble in water; slightly soluble in solutions of carbonic acid and common salt, and readily soluble in concentrated hydrochloric and nitric acid. Of the acid orthophosphates, the mono-calcium salt, CaH_4(PO_4)_2, may be obtained as crystalline scales, containing one molecule of water, by evaporating a solution of the normal salt in hydrochloric or nitric acid. It dissolves readily in water, the solution having an acid reaction. The artificial manure known as "superphosphate of lime" consists of this salt and calcium sulphate, and is obtained by treating ground bones, coprolites, &c., with sulphuric acid. The di-calcium salt, Ca_2H_2(PO_4)_2, occurs in a concretionary form in the ureters and cloaca of the sturgeon, and also in guano. It is obtained as rhombic plates by mixing dilute solutions of calcium chloride and sodium phosphate, and passing carbon dioxide into the liquid. Other phosphates are also known.

_Calcium monosulphide_, CaS, a white amorphous powder, sparingly soluble in water, is formed by heating the sulphate with charcoal, or by heating lime in a current of sulphuretted hydrogen. It is particularly noteworthy from the phosphorescence which it exhibits when heated, or after exposure to the sun's rays; hence its synonym "Canton's phosphorus," after John Canton (1718-1772), an English natural philosopher. The sulphydrate or hydrosulphide, Ca(SH)_2, is obtained as colourless, prismatic crystals of the composition Ca(SH)_2·6H_2O, by passing sulphuretted hydrogen into milk of lime. The strong aqueous solution deposits colourless, four-sided prisms of the hydroxy-hydrosulphide, Ca(OH)(SH). The disulphide, CaS_2 and pentasulphide, CaS_5, are formed when milk of lime is boiled with flowers of sulphur. These sulphides form the basis of Balmain's luminous paint. An oxysulphide, 2CaS·CaO, is sometimes present in "soda-waste," and orange-coloured, acicular crystals of 4CaS·CaSO_4·18H_2O occasionally settle out on the long standing of oxidized "soda- or alkali-waste" (see ALKALI MANUFACTURE).

_Calcium sulphite_, CaSO_3, a white substance, soluble in water, is prepared by passing sulphur dioxide into milk of lime. This solution with excess of sulphur dioxide yields the "bisulphite of lime" of commerce, which is used in the "chemical" manufacture of wood-pulp for paper making.

_Calcium sulphate_, CaSO_4, constitutes the minerals anhydrite (_q.v._), and, in the hydrated form, selenite, gypsum (_q.v._), alabaster (_q.v._), and also the adhesive plaster of Paris (see CEMENT). It occurs dissolved in most natural waters, which it renders "permanently hard." It is obtained as a white crystalline precipitate, sparingly soluble in water (100 parts of water dissolve 24 of the salt at 15°C.), by mixing solutions of a sulphate and a calcium salt; it is more soluble in solutions of common salt and hydrochloric acid, and especially of sodium thiosulphate.

_Calcium silicates_ are exceptionally abundant in the mineral kingdom. Calcium metasilicate, CaSiO_3, occurs in nature as monoclinic crystals known as tabular spar or wollastonite; it may be prepared artificially from solutions of calcium chloride and sodium silicate. H. Le Chatelier (_Annales des mines_, 1887, p. 345) has obtained artificially the compounds: CaSiO_3, Ca_2SiO_4, Ca_3Si_2O_7, and Ca_3SiO_5. (See also G. Oddo, _Chemisches Centralblatt_, 1896, 228.) Acid calcium silicates are represented in the mineral kingdom by gyrolite, H_2Ca_2(SiO_3)_3·H_2O, a lime zeolite, sometimes regarded as an altered form of apophyllite (_q.v._), which is itself an acid calcium silicate containing an alkaline fluoride, by okenite, H_2Ca(SiO_3)_2·H_2O, and by xonalite 4CaSiO_3·H_2O. Calcium silicate is also present in the minerals: olivine, pyroxenes, amphiboles, epidote, felspars, zeolites, scapolites (_qq.v._).

_Detection and Estimation._--Most calcium compounds, especially when moistened with hydrochloric acid, impart an orange-red colour to a Bunsen flame, which when viewed through green glass appears to be finch-green; this distinguishes it in the presence of strontium, whose crimson coloration is apt to mask the orange-red calcium flame (when viewed through green glass the strontium flame appears to be a very faint yellow). In the spectroscope calcium exhibits two intense lines--an orange line ([alpha]), ([lambda] 6163), a green line ([beta]), ([lambda] 4229), and a fainter indigo line. Calcium is not precipitated by sulphuretted hydrogen, but falls as the carbonate when an alkaline carbonate is added to a solution. Sulphuric acid gives a white precipitate of calcium sulphate with strong solutions; ammonium oxalate gives calcium oxalate, practically insoluble in water and dilute acetic acid, but readily soluble in nitric or hydrochloric acid. Calcium is generally estimated by precipitation as oxalate which, after drying, is heated and weighed as carbonate or oxide, according to the degree and duration of the heating.

CALCULATING MACHINES. Instruments for the mechanical performance of numerical calculations, have in modern times come into ever-increasing use, not merely for dealing with large masses of figures in banks, insurance offices, &c., but also, as cash registers, for use on the counters of retail shops. They may be classified as follows:--(i.) Addition machines; the first invented by Blaise Pascal (1642). (ii.) Addition machines modified to facilitate multiplication; the first by G.W. Leibnitz (1671). (iii.) True multiplication machines; Léon Bollés (1888), Steiger (1894). (iv.) Difference machines; Johann Helfrich von Müller (1786), Charles Babbage (1822). (v.) Analytical machines; Babbage (1834). The number of distinct machines of the first three kinds is remarkable and is being constantly added to, old machines being improved and new ones invented; Professor R. Mehmke has counted over eighty distinct machines of this type. The fullest published account of the subject is given by Mehmke in the _Encyclopädie der mathematischen Wissenschaften_, article "Numerisches Rechnen," vol. i., Heft 6 (1901). It contains historical notes and full references. Walther von Dyck's _Catalogue_ also contains descriptions of various machines. We shall confine ourselves to explaining the principles of some leading types, without giving an exact description of any particular one.

Practically all calculating machines contain a "counting work," a series of "figure disks" consisting in the original form of horizontal circular disks (fig. 1), on which the figures 0, 1, 2, to 9 are marked. Each disk can turn about its vertical axis, and is covered by a fixed plate with a hole or "window" in it through which one figure can be seen. On turning the disk through one-tenth of a revolution this figure will be changed into the next higher or lower. Such turning may be called a "step," _positive_ [Sidenote: Addition machines.] if the next higher and _negative_ if the next lower figure appears. Each positive step therefore adds one unit to the figure under the window, while two steps add two, and so on. If a series, say six, of such figure disks be placed side by side, their windows lying in a row, then any number of six places can be made to appear, for instance 000373. In order to add 6425 to this number, the disks, counting from right to left, have to be turned 5, 2, 4 and 6 steps respectively. If this is done the sum 006798 will appear. In case the sum of the two figures at any disk is greater than 9, if for instance the last figure to be added is 8 instead of 5, the sum for this disk is 11 and the 1 only will appear. Hence an arrangement for "carrying" has to be introduced. This may be done as follows. The axis of a figure disk contains a wheel with ten teeth. Each figure disk has, besides, one long tooth which when its 0 passes the window turns the next wheel to the left, one tooth forward, and hence the figure disk one step. The actual mechanism is not quite so simple, because the long teeth as described would gear also into the wheel to the right, and besides would interfere with each other. They must therefore be replaced by a somewhat more complicated arrangement, which has been done in various ways not necessary to describe more fully. On the way in which this is done, however, depends to a great extent the durability and trustworthiness of any arithmometer; in fact, it is often its weakest point. If to the series of figure disks arrangements are added for turning each disk through a required number of steps, [v.04 p.0973] we have an addition machine, essentially of Pascal's type. In it each disk had to be turned by hand. This operation has been simplified in various ways by mechanical means. For pure addition machines key-boards have been added, say for each disk nine keys marked 1 to 9. On pressing the key marked 6 the disk turns six steps and so on. These have been introduced by Stettner (1882), Max Mayer (1887), and in the comptometer by Dorr Z. Felt of Chicago. In the comptograph by Felt and also in "Burrough's Registering Accountant" the result is printed.

These machines can be used for multiplication, as repeated addition, but the process is laborious, depending for rapid execution [Sidenote: MODIFIED ADDITION MACHINES.] essentially on the skill of the operator.[1] To adapt an addition machine, as described, to rapid multiplication the turnings of the separate figure disks are replaced by one motion, commonly the turning of a handle. As, however, the different disks have to be turned through different steps, a contrivance has to be inserted which can be "set" in such a way that by one turn of the handle each disk is moved through a number of steps equal to the number of units which is to be added on that disk. This may be done by making each of the figure disks receive on its axis a ten-toothed wheel, called hereafter the A-wheel, which is acted on either directly or indirectly by another wheel (called the B-wheel) in which the number of teeth can be varied from 0 to 9. This variation of the teeth has been effected in different ways. Theoretically the simplest seems to be to have on the B-wheel nine teeth which can be drawn back into the body of the wheel, so that at will any number from 0 to 9 can be made to project. This idea, previously mentioned by Leibnitz, has been realized by Bohdner in the "Brunsviga." Another way, also due to Leibnitz, consists in inserting between the axis of the handle bar and the A-wheel a "stepped" cylinder. This may be considered as being made up of ten wheels large enough to contain about twenty teeth each; but most of these teeth are cut away so that these wheels retain in succession 9, 8, ... 1, 0 teeth. If these are made as one piece they form a cylinder with teeth of lengths from 9, 8 ... times the length of a tooth on a single wheel.

In the diagrammatic vertical section of such a machine (fig. 2) FF is a figure disk with a conical wheel A on its axis. In the covering plate HK is the window W. A stepped cylinder is shown at B. The axis Z, which runs along the whole machine, is turned by a handle, and itself turns the cylinder B by aid of conical wheels. Above this cylinder lies an axis EE with square section along which a wheel D can be moved. The same axis carries at E' a pair of conical wheels C and C', which can also slide on the axis so that either can be made to drive the A-wheel. The covering plate MK has a slot above the axis EE allowing a rod LL' to be moved by aid of a button L, carrying the wheel D with it. Along the slot is a scale of numbers 0 1 2 ... 9 corresponding with the number of teeth on the cylinder B, with which the wheel D will gear in any given position. A series of such slots is shown in the top middle part of Steiger's machine (fig. 3). Let now the handle driving the axis Z be turned once round, the button being set to 4. Then four teeth of the B-wheel will turn D and with it the A-wheel, and consequently the figure disk will be moved four steps. These steps will be positive or forward if the wheel C gears in A, and consequently four will be added to the figure showing at the window W. But if the wheels CC' are moved to the right, C' will gear with A moving backwards, with the result that four is subtracted at the window. This motion of all the wheels C is done simultaneously by the push of a lever which appears at the top plate of the machine, its two positions being marked "addition" and "subtraction." The B-wheels are in fixed positions below the plate MK. Level with this, but separate, is the plate KH with the window. On it the figure disks are mounted.