Chapter I: Front Matter (1)

Transcriber's notes:

(1) Numbers following letters (without space) like C2 were originally
printed in subscript.

(2) Side-notes were relocated to function as titles of their respective
paragraphs.

(3) Letters topped by Macron are represented as [=x].

(4) Letters topped by Breve are represented as [)x].

(5) The following typographical errors have been corrected:

Article CHOPIN, FREDERIC FRANÇOIS: "which excited the wondering
enthusiasn of Robert Schumann." 'enthusiasn' amended to
'enthusiasm'.

Article CHRISTIANITY: "only in Alexandria was there a genuine
effort make to solve the fundamental problems of God." 'make'
amended to 'made'.

Article CHURCH HISTORY: "This enlargement of the bishop's parish
and multiplication of the chuches under his care led to a change
in the functions of the presbyterate." 'chuches' amended to
'churches'.

Article CIBORIUM: "and in the Western Church the canopy was known
as a 'baldaquin,' Ital. baldacchino, from Baldacco, the Itilian
name of Bagdad." 'Itilian' amended to 'Italian'.

Article CICERO: "In the war between Marius and Sulla has
sympathies were with Sulla, but he did not take up arms" 'has'
amended to 'his'.

ENCYCLOPAEDIA BRITANNICA

A DICTIONARY OF ARTS, SCIENCES, LITERATURE
AND GENERAL INFORMATION

ELEVENTH EDITION

VOLUME VI, SLICE III

Chitral to Cincinnati

ARTICLES IN THIS SLICE:

CHITRAL CHRISTY, HENRY
CHITTAGONG CHROMATIC
CHITTUR CHROMITE
CHITTY, SIR JOSEPH WILLIAM CHROMIUM
CHIUSI CHROMOSPHERE
CHIVALRY CHRONICLE
CHIVASSO CHRONICLES, BOOKS OF
CHIVE CHRONOGRAPH
CHLOPICKI, GREGORZ JOZEF CHRONOLOGY
CHLORAL CHRUDIM
CHLORATES CHRYSANTHEMUM
CHLORINE CHRYSANTHIUS
CHLORITE CHRYSELEPHANTINE
CHLOROFORM CHRYSENE
CHLOROPHYLL CHRYSIPPUS
CHLOROSIS CHRYSOBERYL
CHLORPICRIN CHRYSOCOLLA
CHMIELNICKI, BOGDAN CHRYSOLITE
CHOATE, JOSEPH HODGES CHRYSOLORAS, MANUEL
CHOATE, RUFUS CHRYSOPRASE
CHOBE CHRYSOSTOM
CHOCOLATE CHUB
CHOCTAWS CHUBB, CHARLES
CHODKIEWICZ, JAN KAROL CHUBB, THOMAS
CHODOWIECKI, DANIEL NICOLAS CHUBUT
CHOERILUS CHUDE
CHOEROBOSCUS, GEORGIUS CHUGUYEV
CHOIR CHUKCHI
CHOISEUL, CÉSAR CHULALONGKORN, PHRA
CHOISEUL, ÉTIENNE FRANÇOIS CHUMBI VALLEY
CHOISEUL-STAINVILLE, CLAUDE CHUNAR
CHOISY, FRANÇOIS TIMOLÉON CHUNCHO
CHOLERA CH'UNGK'ING
CHOLET CHUPATTY
CHOLON CHUPRIYA
CHOLONES CHUQUISACA
CHOLULA CHURCH, FREDERICK EDWIN
CHOPIN, FREDERIC FRANÇOIS CHURCH, GEORGE EARL
CHOPSTICKS CHURCH, SIR RICHARD
CHORAGUS CHURCH, RICHARD WILLIAM
CHORALE CHURCH
CHORIAMBIC VERSE CHURCH ARMY
CHORICIUS CHURCH CONGRESS
CHORIN, AARON CHURCH HISTORY
CHORIZONTES CHURCHILL, CHARLES
CHORLEY, HENRY FOTHERGILL CHURCHILL, LORD RANDOLPH
CHORLEY (English town) CHURCHILL (river in Canada)
CHORLU CHURCHING OF WOMEN
CHOROGRAPHY CHURCH RATE
CHÓRUM CHURCHWARDEN
CHORUS CHURCHYARD, THOMAS
CHOSE CHURCHYARD
CHOSROES CHURL
CHOTA CHURN
CHOUANS CHUSAN
CHRESMOGRAPHION CHUTE
CHRESTIEN, FLORENT CHUTNEY
CHRÉTIEN DE TROYES CHUVASHES
CHRISM CIALDINI, ENRICO
CHRIST CIBBER
CHRIST, WILHELM VON CIBBER, COLLEY
CHRISTADELPHIANS CIBORIUM
CHRISTCHURCH (borough in England) CIBRARIO, LUIGI
CHRISTCHURCH (city in New Zealand) CICADA
CHRISTIAN II CICELY
CHRISTIAN III CICERO
CHRISTIAN IV CICERONE
CHRISTIAN V CICHLID
CHRISTIAN VII CICISBEO
CHRISTIAN VIII CICOGNARA, LEOPOLDO
CHRISTIAN IX CID, THE
CHRISTIAN, WILLIAM CIDER
CHRISTIAN OF BRUNSWICK CIENFUEGOS, NICASIO
CHRISTIAN CATHOLIC CHURCH CIENFUEGOS
CHRISTIAN CONNECTION CIEZA
CHRISTIAN ENDEAVOUR SOCIETIES CIGAR
CHRISTIANIA CIGNANI, CARLO
CHRISTIANITY CIGOLI
CHRISTIANSAND CILIA
CHRISTIAN SCIENCE CILIATA
CHRISTIANSUND CILICIA
CHRISTIE, RICHARD COPLEY CILLI, ULRICH
CHRISTINA (queen of Sweden) CILLI (town in Austria)
CHRISTINA (queen-regent of Spain) CIMABUE, GIOVANNI
CHRISTISON, SIR ROBERT CIMAROSA, DOMENICO
CHRISTMAS CIMBRI
CHRISTMAS ISLAND CIMICIFUGA
CHRISTODORUS CIMMERII
CHRISTOPHER, SAINT CIMON
CHRISTOPHORUS CIMON OF CLEONAE
CHRISTOPOULOS, ATHANASIOS CINCHONA
CHRIST'S HOSPITAL CINCINNATI

CHITRAL, a native state in the North-West Frontier Province of India. The state of Chitral (see also HINDU KUSH) is somewhat larger than Wales, and supports a population of about 35,000 rough, hardy hillmen. Previous estimates put the number far higher, but as the Mehtar assesses his fighting strength at 8000 only, this number is probably not far wrong. Both the state and its capital are called Chitral, the latter being situated about 47 m. from the main watershed of the range of the Hindu Kush, which divides the waters flowing down to India from those which take their way into the Oxus. Chitral is an important state because of its situation at the extremity of the country over which the government of India exerts its influence, and for some years before 1895 it had been the object of the policy of the government of India to control the external affairs of Chitral in a direction friendly to British interests, to secure an effective guardianship over its northern passes, and to keep watch over what goes on beyond these passes. This policy resulted in a British agency being established at Gilgit (Kashmir territory), with a subordinate agency in Chitral, the latter being usually stationed at Mastuj (65 m. nearer to Gilgit than the Chitral capital), and occasional visits being paid to the capital. Chitral can be reached either by the long circuitous route from Gilgit, involving 200 m. of hill roads and the passage of the Shandur pass (12,250 ft.), or (more directly) from the Peshawar frontier at Malakand by 100 m. of route through the independent territories of Swat and Bajour, involving the passage of the Lowarai (10,450 ft). It is held by a small force as a British outpost.

The district of Chitral is called Kashgar (or Kashkar) by the people
of the country; and as it was under Chinese domination in the middle
of the 18th century, and was regarded as a Buddhist centre of some
importance by the Chinese pilgrims in the early centuries of our era,
it is possible that it then existed as an outlying district of the
Kashgar province of Chinese Turkestan, where Buddhism once flourished
in cities that have been long since buried beneath the sand-waves of
the Takla Makan. The aboriginal population of the Chitral valley is
probably to be recognized in the people called Kho (speaking a
language called Khowar), who form the majority of its inhabitants.
Upon the Kho a people called Ronas have been superimposed. The Ronas,
who form the chief caste and fighting race of the Chitral districts,
originally came from the north, but they have adopted the language and
fashions of the conquered Chitrali.

The town of Chitral (pop. in 1901, 8128), is chiefly famous for a
siege which it sustained in the spring of 1895. Owing to complications
arising from the demarcation of the boundary of Afghanistan which was
being carried out at that time, and the ambitious projects of Umra
Khan, chief of Jandol, which was a tool in the hands of Sher Afzul, a
political refugee from Chitral supported by the amir at Kabul, the
mehtar (or ruler) of Chitral was murdered, and a small British and
Sikh garrison subsequently besieged in the fort. A large force of
Afghan troops was at that time in the Chitral river valley to the
south of Chitral, nominally holding the Kafirs in check during the
progress of boundary demarcation. It is considered probable that some
of them assisted the Chitralis in the siege. The position of the
political agent Dr Robertson (afterwards Sir George Robertson) and his
military force of 543 men (of whom 137 were non-combatants) was at one
time critical. Two forces were organized for the relief. One was under
Sir R. Low, with 15,000 men, who advanced by way of the Malakand pass,
the Swat river and Dir. The other, which was the first to reach
Chitral, was under Colonel Kelly, commanding the 32nd Pioneers, who
was placed in command of all the troops in the Gilgit district,
numbering about 600 all told, with two guns, and instructed to advance
by the Shandur pass and Mastuj. This force encountered great
difficulties owing to the deep snow on the pass (12,230 ft. high), but
it easily defeated the Chitrali force opposed to it and relieved
Chitral on the 20th of April, the siege having begun on the 4th of
March. Sher Afzul, who had joined Umra Khan, surrendered, and
eventually Chitral was restored to British political control as a
dependency of Kashmir. During Lord Curzon's vice-royalty the British
troops were concentrated at the extreme southern end of the Chitral
country at Kila Drosh and the force was reduced, while the posts
vacated and all outlying posts were handed over to levies raised for
the purpose from the Chitralis themselves. The troops in Swat were
also concentrated at Chakdara and reduced in strength. The mehtar,
Shuja-ul-Mulk, who was installed in September 1895, visited the Delhi
durbar in January 1903.

See Sir George Robertson, _Chitral_ (1898). (T. H. H.*)

CHITTAGONG, a seaport of British India, giving its name to a district and two divisions of Eastern Bengal and Assam. It is situated on the right bank of the Karnaphuli river, about 12 m. from its mouth. It is the terminus of the Assam-Bengal railway. The municipal area covers about 9 sq. m.; pop. (1901) 22,140. The sea-borne exports consist chiefly of jute, other items being tea, raw cotton, rice and hides. There is also a large trade by country boats, bringing chiefly cotton, rice, spices, sugar and tobacco. Since October 1905 Chittagong has become the chief port of the new province of Eastern Bengal and Assam.

The DISTRICT OF CHITTAGONG is situated at the north-east corner of the
province, occupying a strip of coast and hills between the sea and the
mountains of Burma. Its area is 2492 sq. m. In 1901 the population was
1,353,250, showing an increase of 5% in the decade. A few unimportant
ranges rise within the north-eastern portion, the highest hill being
the sacred Sitakund, 1155 ft. high. The principal rivers are the
Karnaphuli, on which Chittagong town is situated, navigable by
sea-going ships as far as Chittagong port, and by large trading boats
for a considerable distance higher up, and the Halda and the Sangu,
which are also navigable by large boats. The wild animals are tigers,
elephants, rhinoceros, leopards and deer. The climate is comparatively
cool, owing to the sea breeze which prevails during the day; but for
the same reason, the atmosphere is very moist, with heavy dews at
night and fogs. Chittagong was ceded to the East India Company by
Nawab Mir Kasim in 1760. The northern portion of the district is
traversed by the Assam-Bengal railway. Tea cultivation is moderately
successful.

The CHITTAGONG HILL TRACTS formed an independent district from 1860 to
1891, were then reduced to the status of a sub-division, but were
again created a district in 1900. They occupy the ranges between
Chittagong proper and the south Lushai hills. The area covers 5138 sq.
m. In 1901 the population was 124,762, showing an increase of 16% in
the decade. The inhabitants, who are either Arakanese or aboriginal
tribes, are almost all Buddhists. The headquarters are at Rangamati,
which was wrecked by the cyclone of October 1897.

The DIVISION OF CHITTAGONG lies at the north-east corner of the Bay of
Bengal, extending northward along the left bank of the Meghna. It
consists of the districts of Chittagong, the Hill Tracts, Noakhali and
Tippera. Its area covers 11,773 sq. m.; the population in 1901 was
4,737,731.

CHITTUR, a town of British India, in the North Arcot district of Madras, with a station on the South Indian railway. Pop. (1901) 10,893. Formerly a military cantonment, it is now only the civil headquarters of the district. It has an English church, mission chapel, and Roman Catholic chapel, a high school, and several literary institutes.

CHITTY, SIR JOSEPH WILLIAM (1828-1899), English judge, was born in London. He was the second son of Thomas Chitty (himself son and brother of well-known lawyers), a celebrated special pleader and writer of legal text-books, in whose pupil-room many distinguished lawyers began their legal education. Joseph Chitty was educated at Eton and Balliol, Oxford, gaining a first-class in _Literae Humaniores_ in 1851, and being afterwards elected to a fellowship at Exeter College. His principal distinctions during his school and college career had been earned in athletics, and he came to London as a man who had stroked the Oxford boat and captained the Oxford cricket eleven. He became a member of Lincoln's Inn in 1851, was called to the bar in 1856, and made a queen's counsel in 1874, electing to practise as such in the court in which Sir George Jessel, master of the rolls, presided. Chitty was highly successful in his method of dealing with a very masterful if exceedingly able judge, and soon his practice became very large. In 1880 he entered the house of commons as liberal member for Oxford (city). His parliamentary career was short, for in 1881 the Judicature Act required that the master of the rolls should cease to sit regularly as a judge of first instance, and Chitty was selected to fill the vacancy thus created in the chancery division. Sir Joseph Chitty was for sixteen years a popular judge, in the best meaning of the phrase, being noted for his courtesy, geniality, patience and scrupulous fairness, as well as for his legal attainments, and being much respected and liked by those practising before him, in spite of a habit of interrupting counsel, possibly acquired through the example of Sir George Jessel. In 1897, on the retirement of Sir Edward Kay, L.J., he was promoted to the court of appeal. There he more than sustained--in fact, he appreciably increased--his reputation as a lawyer and a judge, proving himself to possess considerable knowledge of the common law as well as of equity. He died in London on the 15th of February 1899. He married in 1858 Clara Jessie, daughter of Chief Baron Pollock, and left children who could thus claim descent from two of the best-known English legal families of the 19th century.

See E. Manson, _Builders of our Law_ (1904).

CHIUSI (anc. _Clusium_), a town of Tuscany, Italy, in the province of Siena, 55 m. S.E. by rail from the town of Siena, and 26 m. N.N.W. of Orvieto. Pop. (1901) 6011. It is situated on a hill 1305 ft. above sea-level, and is surrounded by medieval walls, in which, in places, fragments of the Etruscan wall are incorporated. The cathedral of S. Mustiola is a basilica with a nave and two aisles, with eighteen columns of different kinds of marble, from ancient buildings. It has been restored and decorated with frescoes in modern times. The campanile belongs to the 13th century. The place was devastated by malaria in the middle ages, and did not recover until the Chiana valley was drained in the 18th century. For the catacombs see CLUSIUM.

CHIVALRY (O. Fr. _chevalerie_, from Late Lat. _caballerius_), the knightly class of feudal times, possessing its own code of rules, moral and social (see KNIGHTHOOD AND CHIVALRY). The primary sense in the middle ages is "knights" or "fully armed and mounted fighting men." Thence the term came to mean that gallantry in battle and high sense of honour in general expected of knights. Thus "to do chivalry" was a medieval phrase for "to act the knight." Lastly, the word came to be used in its present very general sense of "courtesy." In English law chivalry meant the tenure of land by knights' service. It was a service due to the crown, usually forty days' military attendance annually. The _Court of Chivalry_ was a court instituted by Edward III., of which the lord high constable and earl marshal of England were joint judges. When both sat the court had summary criminal jurisdiction as regards all offences committed by knights, and generally as to military matters. When the earl marshal alone presided, it was a court of honour deciding as to precedence, coats of arms, &c. This court sat for the last time in 1737. The heraldic side of its duties are now vested in the earl marshal as head of the Heralds' College.

CHIVASSO, a town and episcopal see of Piedmont, Italy, in the province of Turin, 18 m. N.E. by rail from the town of Turin, 600 ft. above sea-level. Pop. (1901) 4169 (town), 9804 (commune). It is situated on the left bank of the Po, near the influx of the Orco. The cathedral is of the 15th century with a fine façade ornamented with statues in terra-cotta. It was an important fortress in the middle ages, and until 1804, when the French dismantled it. One tower only of the old castle of the marquesses of Monferrato, who possessed the town from 1164 to 1435, remains. Chivasso is on the main line from Turin to Milan, and is the junction of branches for Aosta and Casale Monferrato.

CHIVE (_Allium Schoenoprasum_), a hardy perennial plant, with small narrow bulbs tufted on short root-stocks and long cylindrical hollow leaves. It is found in the north of England and in Cornwall, and growing in rocky pastures throughout temperate and northern Europe and Asiatic Russia, and also in the mountain districts of southern Europe. It is cultivated for the sake of its leaves, which are used in salads and soups as a substitute for young onions. It will grow in any good soil, and is propagated by dividing the roots into small clumps in spring or autumn; these are planted from 8 to 12 in. apart and soon form large tufts. The leaves should be cut frequently so as to obtain them tender and succulent.

CHLOPICKI, GREGORZ JOZEF (1772-1854), Polish general, was born in March 1772 in Podolia. He was educated at the school of the Basilians at Szarogrod, from which in 1787 he ran away in order to enlist as a volunteer in the Polish army. He was present at all the engagements fought during 1792-1794, especially distinguishing himself at the battle of Raclawice, when he was General Rymkiewicz's adjutant. On the formation of the Italian legion he joined the second battalion as major, and was publicly complimented by General Oudinot for his extraordinary valour at the storming of Peschiera. He also distinguished himself at the battles of Modena, Busano, Casabianca and Ponto. In 1807 he commanded the first Vistulan regiment, and rendered good service at the battles of Eylau and Friedland. In Spain he obtained the legion of honour and the rank of a French baron for his heroism at the battle of Epila and the storming of Saragossa, and in 1809 was promoted to be general of brigade. In 1812 he accompanied the _Grande Armée_ to Russia, was seriously wounded at Smolensk, and on the reconstruction of the Polish army in 1813 was made a general of division. On his return to Poland in 1814, he entered the Russian army with the rank of a general officer, but a personal insult from the grand duke Constantine resulted in his retiring into private life. He held aloof at first from the Polish national rising of 1830, but at the general request of his countrymen accepted the dictatorship on the 5th of December 1830; on the 23rd of January 1831, however, he resigned in order to fight as a common soldier. At Wavre (Feb. 19) and at Grochow (Feb. 20) he displayed all his old bravery, but was so seriously wounded at the battle of Olszyna that he had to be conveyed to Cracow, near which city he lived in complete retirement till his death in 1854.

See Jozef Maczynski, _Life and Death of Joseph Chlopicki_ (Pol.)
(Cracow, 1858); Ignacy Pradzynski, _The Four Last Polish Commanders_
(Pol.) (Posen, 1865).

CHLORAL, or TRICHLORACETALDEHYDE, CCl3·CHO, a substance discovered by J. von Liebig in 1832 (_Ann._, 1832, 1, p. 189) and further studied by J.B.A. Dumas and Staedeler. It is a heavy, oily and colourless liquid, of specific gravity 1.541 at 0° C., and boiling-point 97.7° C. It has a greasy, somewhat bitter taste, and gives off a vapour at ordinary temperature which has a pungent odour and an irritating effect on the eyes. The word _chloral_ is derived from the first syllables of _chlorine_ and _alcohol_, the names of the substances employed for its preparation. Chloral is soluble in alcohol and ether, in less than its own weight of water, and in four times its weight of chloroform; it absorbs chlorine, and dissolves bromine, iodine, phosphorus and sulphur. Chloral deliquesces in the air, and is converted by water into a hydrate, with evolution of heat; it combines with alcohols and mercaptans. An ammoniacal solution of silver nitrate is reduced by chloral; and nascent hydrogen converts it into aldehyde. By means of phosphorus pentachloride, chlorine can be substituted for the oxygen of chloral, the body CCl3·CCl2H being produced; an analogous compound, CCl3·C(C6H5)2H, is obtained by treating chloral with benzene and sulphuric acid. With an alkali, chloral gives chloroform (q.v.) and a formate; oxidizing agents give trichloracetic acid, CCl3·CO(OH). When kept for some days, as also when placed in contact with sulphuric acid or a very small quantity of water, chloral undergoes spontaneous change into the polymeride _metachloral_ (C2Cl3OH)3, a white porcellaneous body, slowly volatile in the air, and reconverted into chloral without melting at 180° C. Chloral unites directly with hydrocyanic acid to form [beta]-trichloracetonitrile, CCl3·CH(OH)CN, and with hydroxylamine it forms chlorglyoxime, C2H3ClN2O2.

Chloral is prepared by passing dry chlorine into absolute alcohol; the latter must be cooled at first, but towards the end of the operation has to be heated nearly to boiling. The alcohol is converted finally into a syrupy fluid, from which chloral is procured by treatment with sulphuric acid (see P. Fritsch, _Ann._, 1894, pp. 279, 288). The crude chloral is distilled over lime, and is purified by further treatment with sulphuric acid, and by redistillation. A mixture of starch or sugar with manganese peroxide and hydrochloric acid may be employed instead of alcohol and chlorine for the manufacture of chloral (A. Staedeler, _Ann. Ch. Pharm._, 1847, 61, p. 101). An isomer of chloral, _parachloralide_, is made by passing excess of dry chlorine into absolute methyl alcohol.

_Chloral hydrate_, CCl3·CH(OH)2, forms oblique, often very short,
rhombic prisms. The crystals are perfectly transparent, only slightly
odorous, free from powder, and dry to the touch, and do not become
white by exposure. The melting-point of pure chloral hydrate is 57°,
the boiling-point 96-98° C. When heated with sulphuric acid it is
converted into anhydrous chloral and _chloralide_, C6H2Cl6O3. When
mixed with water, chloral hydrate causes a considerable degree of
cold; and, as with camphor, small fragments of it placed on the
surface of water exhibit gyratory movements. Chloral hydrate does not
restore the colour to a solution of fuchsine which has been
decolorized by sulphurous acid, and so one must assume that the water
present is combined in the molecular condition (V. Meyer, _Ber._,
1880, 13, p. 2343). Chloral may be estimated by distilling the hydrate
with milk of lime and measuring the volume of chloroform produced
(C.H. Wood, _Pharm. Journ._, (3) 1, p. 703), or by hydrolysis with a
known volume of standard alkali and back titration with standard acid
(V. Meyer, _Ber._, 1873, 6, p. 600). Chloral hydrate has the property
of checking the decomposition of a great number of albuminous
substances, such as milk and meat; and a mixture of it with glycerin,
according to J. Personne, is suitable for the preservation of
anatomical preparations. When heated with concentrated glycerin to a
temperature of 110° to 230° C, chloral hydrate yields chloroform,
CHCl3, and allyl formate, HCO(OC3H5).

_Pharmacology and Therapeutics._--The breaking up of chloral hydrate,
in the presence of alkalis, with the production of chloroform and
formates, led Liebreich to the conjecture that a similar decomposition
might be produced in the blood; and hence his introduction of the
drug, in 1869, as an anaesthetic and hypnotic. It is now known,
however, that the drug circulates in the blood unchanged, and is
excreted in the form of urochloralic acid. The dose is from five to
twenty grains or somewhat more, and it is often given in the form of
the pharmacopoeial _Syrupus Chloral_, which contains ten grains of
chloral hydrate to the fluid drachm. Chloral hydrate must be well
diluted when given by the mouth, as otherwise it may cause
considerable gastro-intestinal irritation. In large doses chloral
hydrate is a depressant to the circulation and the respiration, and
also lowers the temperature. In the above doses the drug is a powerful
and safe hypnotic, acting directly on the brain, and producing no
preliminary stage of excitement. Very soon--perhaps twenty
minutes--after taking such a dose, the patient falls into a sleep
which lasts several hours, and is not distinguishable from natural
sleep. When he wakes, it is without disagreeable after-symptoms, but
with a feeling of natural refreshment. The pupils are always
contracted under its influence, except in large doses. There is also
rapidly induced a depression of the anterior horns of grey matter in
the spinal cord, and as the symptoms of strychnine poisoning are due
to violent stimulation of these areas, chloral hydrate is a valuable
antidote in such cases. It should not be hypodermically injected. Its
disadvantages are that it is powerless when there is pain, resembling
in this feature nearly all hypnotics except opium (morphine) and
hyoscin. Its action on the gastro-intestinal canal and on the
respiratory and circulatory systems renders its use inadvisable when
disease of these organs is present. Its action on the spinal cord has
been employed with success in cases of tetanus, whooping-cough,
urinary incontinence, and strychnine poisoning. In the latter case
twenty grains in "normal saline" solution may be directly injected
into a subcutaneous vein, but not into the subcutaneous tissues.

_Toxicology._--In cases of acute poisoning by chloral hydrate, the
symptoms may be summarized as those of profound coma. The treatment is
to give a stimulant emetic such as mustard; to keep up the temperature
by hot bottles, &c.; to prevent or disturb the patient's morbid sleep
by the injection of hot strong coffee into the rectum; and by
shouting, flipping with towels, &c.; to use artificial respiration in
extreme cases; and to inject strychnine. Strychnine is much less
likely, however, to save life after poisoning by chloral hydrate, than
chloral hydrate is to save life in poisoning by strychnine.

Chronic poisoning by chloral is a most pernicious drug-habit. The vice
is easily and very rapidly acquired. The victim is usually excited and
loquacious. He is easily fatigued and suffers from attacks of easily
induced syncope. There are signs of gastro-intestinal irritation, and
a tendency to cutaneous eruptions of an erythematous type. The patient
may succumb to a dose only slightly larger than usual. The treatment
is on general principles, there being no specific remedy. The patient
must be persuaded to put himself under restraint, and the drug must be
stopped at once and entirely.

CHLORATES, the metallic salts of chloric acid; they are all solids, soluble in water, the least soluble being the potassium salt. They may be prepared by dissolving or suspending a metallic oxide or hydroxide in water and saturating the solution with chlorine; by double decomposition; or by neutralizing a solution of chloric acid by a metallic oxide, hydroxide or carbonate. They are all decomposed on heating, with evolution of oxygen; and in contact with concentrated sulphuric acid with liberation of chlorine peroxide. The most important is potassium chlorate, KClO3, which was obtained in 1786 by C.L. Berthollet by the action of chlorine on caustic potash, and this method was at first used for its manufacture. The modern process consists in the electrolysis of a hot solution of potassium chloride, or, preferably, the formation of sodium chlorate by the electrolytic method and its subsequent decomposition by potassium chloride. (See ALKALI MANUFACTURE.) Potassium chlorate crystallizes in large white tablets, of a bright lustre. It melts without decomposition, and begins to give off oxygen at about 370° C. According to F.L. Teed (_Proc. Chem. Soc._, 1886, p. 141), the decomposition of potassium chlorate by heat is not at all simple, the quantities of chloride and perchlorate produced depending on the temperature. A very gentle heating gives decomposition approximating to the equation of 22KClO3 = 14KClO4 + 8KCl + 5O2, whilst on a more rapid heating the quantities correspond more nearly to 10KClO3 = 6KClO4 + 4KCl + 3O2. The decomposition is rendered more easy and regular by mixing the salt with powdered manganese dioxide. The salt finds application in the preparation of oxygen, in the manufacture of matches, for pyrotechnic purposes, and in medicine. Sodium chlorate, NaClO3, is prepared by the electrolytic process; by passing chlorine into milk of lime and decomposing the calcium chlorate formed by sodium sulphate; or by the action of chlorine on sodium carbonate at low temperature (not above 35° C). It is much more soluble in water than the potassium salt.

Potassium chlorate is very valuable in medicine. Given in large doses it causes rapid and characteristic poisoning, with alterations in the blood and rapid degeneration of nearly all the internal organs; but in small doses--5 to 15 grains--it partly undergoes reduction in the blood and tissues, the chloride being formed and oxygen being supplied to the body-cells in nascent form. Its special uses are in ulceration of the mouth or tongue (_ulcerative stomatitis_), tonsillitis and pharyngitis. For these conditions it is administered in the form of a lozenge, but may also be swallowed in solution, as it is excreted by the saliva and so reaches the diseased surface. Its remarkable efficacy in healing ulcers of the mouth--for which it is the specific--has been ascribed to a decomposition effected by the carbonic acid which is given off from these ulcers. This releases chloric acid, which, being an extremely powerful antiseptic, kills the bacteria to which the ulcers are due.

CHLORINE (symbol Cl), atomic weight 35.46 (O = 16), a gaseous chemical element of the halogen group, taking its name from the colour, greenish-yellow (Gr. [Greek: chloros]). It was discovered in 1774 by Scheele, who called it _dephlogisticated muriatic acid_; about 1785, C.L. Berthollet, regarding it as being a compound of hydrochloric acid and oxygen, termed it _oxygenized muriatic acid_. This view was generally held until about 1810-1811, when Sir H. Davy showed definitely that it was an element, and gave it the name which it now bears.

Chlorine is never found in nature in the uncombined condition, but in combination with the alkali metals it occurs widely distributed in the form of rock-salt (sodium chloride); as sylvine and carnallite, at Stassfürt; and to a smaller extent in various other minerals such as matlockite and horn-mercury. In the form of alkaline chlorides it is found in sea-water and various spring waters, and in the tissues of animals and plants; while, as hydrochloric acid it is found in volcanic gases.

The preparation of chlorine, both on the small scale and commercially, depends on the oxidation of hydrochloric acid; the usual oxidizing agent is manganese dioxide, which, when heated with concentrated hydrochloric acid, forms manganese chloride, water and chlorine:--MnO2 + 4HCl = MnCl2 + 2H2O + Cl2. The manganese dioxide may be replaced by various other substances, such as red lead, lead dioxide, potassium bichromate, and potassium permanganate. Instead of heating hydrochloric acid with manganese dioxide, use is frequently made of a mixture of common salt and manganese dioxide, to which concentrated sulphuric acid is added and the mixture is then heated:--MnO2 + 2NaCl + 3H2SO4 = MnSO4 + 2NaHSO4 + 2H2O + Cl2. Chlorine may also be obtained by the action of dilute sulphuric acid on bleaching powder.

Owing to the enormous quantities of chlorine required for various industrial purposes, many processes have been devised, either for the recovery of the manganese from the crude manganese chloride of the chlorine stills, so that it can be again utilized, or for the purpose of preparing chlorine without the necessity of using manganese in any form (see ALKALI MANUFACTURE).

Owing to the reduction in the supply of available hydrochloric acid
(on account of the increasing use of the "ammonia-soda" process in
place of the "Leblanc" process for the manufacture of soda) Weldon
tried to adapt the former to the production of chlorine or
hydrochloric acid. His method consisted in using magnesia instead of
lime for the recovery of the ammonia (which occurs in the form of
ammonium chloride in the ammonia-soda process), and then by
evaporating the magnesium chloride solution and heating the residue in
steam, to condense the acid vapours and so obtain hydrochloric acid.
One day before him E. Solvay had patented the same process, but
neither of them was able to make the method a commercial success.
However, in conjunction with Pechiney, of Salindres (near Alais,
France), the Weldon-Pechiney process was worked out. The residual
magnesium chloride of the ammonia-soda process is evaporated until it
ceases to give off hydrochloric acid, and is then mixed with more
magnesia: the magnesium oxychloride formed is broken into small pieces
and heated in a current of air, when it gives up its chlorine, partly
in the uncombined condition and partly in the form of hydrochloric
acid, and leaves a residue of magnesia, which can again be utilized
for the decomposition of more ammonium chloride (W. Weldon, _Journ. of
Soc. of Chem. Industry_, 1884, p. 387). Greater success attended the
efforts of Ludwig Mond, of the firm of Brunner, Mond & Co. In this
process the ammonium chloride is volatilized in large iron retorts
lined with Doulton tiles, and then led into large upright wrought-iron
cylinders lined with fire-bricks. These cylinders are filled with
pills, made of a mixture of magnesia, potassium chloride and fireclay,
the object of the potassium chloride being to prevent any formation of
hydrochloric acid, which might occur if the magnesia was not perfectly
dry. At 300° C. the ammonium chloride is decomposed by the magnesia,
with the formation of magnesium chloride and ammonia. The mixture is
now heated to 600° C. in a current of hot dry gas, containing no free
oxygen (the gas from the carbonating plant being used), and then a
current of air at the same temperature is passed in. Decomposition
takes place and the issuing gas contains 18-20% of chlorine. This
percentage drops gradually, and when it is reduced to about 3% the
temperature of the apparatus is lowered, by the admission of air, to
about 350° C., and the air stream containing the small percentage of
chlorine is led off to a second cylinder of pills, which have just
been treated with ammonium chloride vapour and are ready for the hot
air current. With four cylinders the process is continuous (L. Mond,
_British Assoc. Reports_, 1896, p. 734).

More recently, owing to the production of caustic soda by electrolytic
methods, much chlorine has consequently been produced in the same
manner (see ALKALI MANUFACTURE).

Chlorine is a gas of a greenish-yellow colour, and possesses a characteristic unpleasant and suffocating smell. It can be liquefied at -34° C. under atmospheric pressure, and at -102° C. it solidifies and crystallizes. Its specific heat at constant pressure is 0.1155, and at constant volume 0.08731 (A. Strecker, _Wied. Ann._, 1877 [2], 13, p. 20); and its refractive index 1.000772, whilst in the liquid condition the refractive index is 1.367. The density is 2.4885 (air = 1) (Treadwell and Christie, _Zeit. anorg. Chem._, 1905, 47, p. 446). Its critical temperature is 146° C. Liquid and solid chlorine are both yellow in colour. The gas must be collected either by downward displacement, since it is soluble in water and also attacks mercury; or over a saturated salt solution, in which it is only slightly soluble. At ordinary temperatures it unites directly with many other elements; thus with hydrogen, combination takes place in direct sunlight with explosive violence; arsenic, antimony, thin copper foil and phosphorus take fire in an atmosphere of chlorine, forming the corresponding chlorides. Many compounds containing hydrogen are readily decomposed by the gas; for example, a piece of paper dipped in turpentine inflames in an atmosphere of chlorine, producing hydrochloric acid and a copious deposit of soot; a lighted taper burns in chlorine with a dull smoky flame. The solution of chlorine in water, when freshly prepared, possesses a yellow colour, but on keeping becomes colourless, on account of its decomposition into hydrochloric acid and oxygen. It is on this property that its bleaching and disinfecting power depends (see BLEACHING). Water saturated with chlorine at 0° C. deposits crystals of a hydrate Cl2·8H2O, which is readily decomposed at a higher temperature into its constituents. Chlorine hydrate has an historical importance, as by sealing it up in a bent tube, and heating the end containing the hydrate, whilst the other limb of the tube was enclosed in a freezing mixture, M. Faraday was first able to obtain liquid chlorine.

Chlorine is used commercially for the extraction of gold (q.v.) and
for the manufacture of "bleaching powder" and of chlorates. It also
finds an extensive use in organic chemistry as a substituting and
oxidizing agent, as well as for the preparation of addition compounds.
For purposes of substitution, the free element as a rule only works
slowly on saturated compounds, but the reaction may be accelerated by
the action of sunlight or on warming, or by using a "carrier." In
these latter cases the reaction may proceed in different directions;
thus, with the aromatic hydrocarbons, chlorine in the cold or in the
presence of a carrier substitutes in the benzene nucleus, but in the
presence of sunlight or on warming, substitution takes place in the
side chain. Iodine, antimony trichloride, molybdenum pentachloride,
ferric chloride, ferric oxide, antimony, tin, stannic oxide and
ferrous sulphate have all been used as chlorine carriers.

The atomic weight of chlorine was determined by J. Berzelius and by
F. Penny (_Phil, Trans._, 1839, 13). J.S. Stas, from the synthesis of
silver chloride, obtained the value 35.457 (O = 16), and C. Marignac
found the value 34.462. More recent determinations are: H.B. Dixon and
E.C. Edgar (_Phil. Trans._, 1905); T.W. Richards and G. Jones (_Abst.
J.C.S._, 1907); W.A. Noyes and H.C. Weber (ibid., 1908), and Edgar
(ibid., 1908).

_Hydrochloric Acid._--Chlorine combines with hydrogen to form hydrochloric acid, HCl, the only known compound of these two elements. The acid itself was first obtained by J.R. Glauber in about 1648, but J. Priestley in 1772 was the first to isolate it in the gaseous condition, and Sir H. Davy in 1810 showed that it contained hydrogen and chlorine only, as up to that time it was considered to contain oxygen. It may be prepared by the direct union of its constituents (see Burgess and Chapman, _J.C.S._, 1906, 89, p. 1399), but on the large scale and also for the preparation of small quantities it is made by the decomposition of salt by means of concentrated sulphuric acid, NaCl+H2SO4=NaHSO4+HCl. It is chiefly obtained as a by-product in the manufacture of soda-ash by the Leblanc process (see ALKALI MANUFACTURE). The commercial acid is usually yellow in colour and contains many impurities, such as traces of arsenic, sulphuric acid, chlorine, ferric chloride and sulphurous acid; but these do not interfere with its application to the preparation of bleaching powder, in which it is chiefly consumed. Without further purification it is also used for "souring" in bleaching, and in tin and lead soldering.

It is a colourless gas, which can be condensed by cold and pressure to
a liquid boiling at -83.7° C., and can also be solidified, the solid
melting at -112.5° C. (K. Olszewski). Its critical temperature is
52.3° C., and its critical pressure is 86 atmos. The gas fumes
strongly in moist air, and it is rapidly dissolved by water, one
volume of water at 0° C. absorbing 503 volumes of the gas. The gas
does not obey Henry's law, that is, its solubility in water is not
proportional to its pressure. It is one of the "strong" acids, being
ionized to the extent of about 91.4% in decinormal solution. The
strongest aqueous solution of hydrochloric acid at 15° C. contains
42.9% of the acid, and has a specific gravity of 1.212. Perfectly dry
hydrochloric acid gas has no action on metals, but in aqueous solution
it dissolves many of them with evolution of hydrogen and formation of
chlorides.

The salts of hydrochloric acid, known as _chlorides_, can, in most
cases, be prepared by dissolving either the metal, its hydroxide,
oxide, or carbonate in the acid; or by heating the metal in a current
of chlorine, or by precipitation. The majority of the metallic
chlorides are solids (stannic chloride, titanic chloride and antimony
pentachloride are liquids) which readily volatilize on heating. Many
are readily soluble in water, the chief exceptions being silver
chloride, merçurous chloride, cuprous chloride and palladious chloride
which are insoluble in water, and thallous chloride and lead chloride
which are only slightly soluble in cold water, but are readily soluble
in hot water. Bismuth and antimony chlorides are decomposed by water
with production of oxychlorides, whilst titanium tetrachloride yields
titanic acid under the same conditions. All the metallic chlorides,
with the exception of those of the alkali and alkaline earth metals,
are reduced either to the metallic condition or to that of a lower
chloride on heating in a current of hydrogen; most are decomposed by
concentrated sulphuric acid. They can be distinguished from the
corresponding bromides and iodides by the fact that on distillation
with a mixture of potassium bichromate and concentrated sulphuric acid
they yield chromium oxychloride, whereas bromides and iodides by the
same treatment give bromine and iodine respectively. Some metallic
chlorides readily form double chlorides, the most important of these
double salts being the platinochlorides of the alkali metals. The
chlorides of the non-metallic elements are usually volatile fuming
liquids of low boiling-point, which can be distilled without
decomposition and are decomposed by water. Hydrochloric acid and its
metallic salts can be recognized by the formation of insoluble silver
chloride, on adding silver nitrate to their nitric acid solution, and
also by the formation of chromium oxychloride (see above). Chlorides
can be estimated quantitatively by conversion into silver chloride, or
if in the form of alkaline chlorides (in the absence of other metals,
and of any free acids) by titration with standard silver nitrate
solution, using potassium chromate as an indicator.

Chlorine and oxygen do not combine directly, but compounds can be
obtained indirectly. Three oxides are known: chlorine monoxide, Cl2O,
chlorine peroxide, ClO2, and chlorine heptoxide, Cl2O7.

Chlorine monoxide results on passing chlorine over dry precipitated
mercuric oxide. It is a pale yellow gas which can be condensed, on
cooling, to a dark-coloured liquid boiling at 5° C. (under a pressure
of 737.9 mm.). It is extremely unstable, decomposing with extreme
violence on the slightest shock or disturbance, or on exposure to
sunlight. It is readily soluble in water, with which it combines to
form hypochlorous acid. Sulphur, phosphorus, carbon compounds, and
the alkali metals react violently with the gas, taking fire with
explosive decomposition. A.J. Balard determined the volume composition
of the gas by decomposition over mercury on gentle warming, followed
by the absorption of the chlorine produced with potassium hydroxide,
and then measured the residual oxygen.

Chlorine peroxide was first obtained by Sir H. Davy in 1815 by the
action of concentrated sulphuric acid on potassium chlorate. As this
oxide is a dangerous explosive, great care must be taken in its
preparation; the chlorate is finely powdered and added in the cold, in
small quantities at a time, to the acid contained in a retort. After
solution the retort is gently heated by warm water when the gas is
liberated:--3KClO3 + 2H2SO4 = KClO4 + 2KHSO4 + H2O + ClO2. A mixture
of chlorine peroxide and chlorine is obtained by the action of
hydrochloric acid on potassium chlorate, and similarly, on warming a
mixture of potassium chlorate and oxalic acid to 70° C. on the water
bath, a mixture of chlorine peroxide and carbon dioxide is obtained.
Chlorine peroxide must be collected by displacement, as it is soluble
in water and readily attacks mercury. It is a heavy gas of a deep
yellow colour and possesses an unpleasant smell. It can be liquefied,
the liquid boiling at 9.9° C., and on further cooling it solidifies at
-79° C. It is very explosive, being resolved into its constituents by
influence of light, on warming, or on application of shock. It is a
very powerful oxidant; a mixture of potassium chlorate and sugar in
about equal proportions spontaneously inflames when touched with a rod
moistened with concentrated sulphuric acid, the chlorine peroxide
liberated setting fire to the sugar, which goes on burning. Similarly,
phosphorus can be burned under water by covering it with a little
potassium chlorate and running in a thin stream of concentrated
sulphuric acid (see papers by Bray, _Zeit. phys. Chem._, 1906, et
seq.).

Chlorine heptoxide was obtained by A. Michael by slowly adding
perchloric acid to phosphoric oxide below -10° C.; the mixture is
allowed to stand for a day and then gently warmed, when the oxide
distils over as a colourless very volatile oil of boiling-point 82° C.
It turns to a greenish-yellow colour in two or three days and gives
off a greenish gas; it explodes violently on percussion or in contact
with a flame, and is gradually converted into perchloric acid by the
action of water. On the addition of iodine to this oxide, chlorine is
liberated and a white substance is produced, which decomposes, on
heating to 380° C, into iodine and oxygen; bromine is without action
(see A. Michael, _Amer. Chem. Jour._, 1900, vol. 23; 1901, vol. 25).

Several oxy-acids of chlorine are known, namely, hypochlorous acid,
HClO, chlorous acid, HClO2 (in the form of its salts), chloric acid,
HClO3, and perchloric acid, HClO4. Hypochlorous acid is formed when
chlorine monoxide dissolves in water, and can be prepared (in dilute
solution) by passing chlorine through water containing precipitated
mercuric oxide in suspension. Precipitated calcium carbonate may be
used in place of the mercuric oxide, or a hypochlorite may be
decomposed by a dilute mineral acid and the resulting solution
distilled. For this purpose a filtered solution of bleaching-powder
and a very dilute solution of nitric acid may be employed. The acid is
only known in aqueous solution, and only dilute solutions can be
distilled without decomposition. The solution has a pale yellow
colour, and is a strong oxidizing and bleaching agent; it is readily
decomposed by hydrochloric acid, with evolution of oxygen. The salts
of this acid are known as hypochlorites, and like the acid itself are
very unstable, so that it is almost impossible to obtain them pure. A
solution of sodium hypochlorite (_Eau de Javel_), which can be
prepared by passing chlorine into a cold aqueous solution of caustic
soda, has been extensively used for bleaching purposes. One of the
most important derivatives of hypochlorous acid is bleaching powder.
Sodium hypochlorite can be prepared by the electrolysis of brine
solution in the presence of carbon electrodes, having no diaphragm in
the electrolytic cell, and mixing the anode and cathode products by
agitating the liquid. The temperature should be kept at about 15° C.,
and the concentration of the hypochlorite produced must not be allowed
to become too great, in order to prevent reduction taking place at the
cathode.

Chlorous acid is not known in the pure condition; but its sodium salt
is prepared by the action of sodium peroxide on a solution of chlorine
peroxide: 2ClO2 + Na2O2 = 2NaClO2 + O2. The silver and lead salts are
unstable, being decomposed with explosive violence at 100° C. On
adding a caustic alkali solution to one of chlorine peroxide, a
mixture of a chlorite and a chlorate is obtained.

Chloric acid was discovered in 1786 by C.L. Berthollet, and is best
prepared by decomposing barium chlorate with the calculated amount of
dilute sulphuric acid. The aqueous solution can be concentrated _in
vacuo_ over sulphuric acid until it contains 40% of chloric acid.
Further concentration leads to decomposition, with evolution of oxygen
and formation of perchloric acid. The concentrated solution is a
powerful oxidizing agent; organic matter being oxidized so rapidly
that it frequently inflames. Hydrochloric acid, sulphuretted hydrogen
and sulphurous acid are rapidly oxidized by chloric acid. J.S. Stas
determined its composition by the analysis of pure silver chlorate.
The salts of this acid are known as chlorates (q.v.).

Perchloric acid is best prepared by distilling potassium perchlorate
with concentrated sulphuric acid. According to Sir H. Roscoe, pure
perchloric acid distils over at first, but if the distillation be
continued a white crystalline mass of hydrated perchloric acid,
HClO4·H2O, passes over; this is due to the decomposition of some of
the acid into water and lower oxides of chlorine, the water produced
then combining with the pure acid to produce the hydrated form. This
solid, on redistillation, gives the pure acid, which is a liquid
boiling at 39° C. (under a pressure of 56 mm.) and of specific gravity
1.764 (22/4)°. The crystalline hydrate melts at 50° C. The pure acid
decomposes slowly on standing, but is stable in dilute aqueous
solution. It is a very powerful oxidizing agent; wood and paper in
contact with the acid inflame with explosive violence. In contact with
the skin it produces painful wounds. It may be distinguished from
chloric acid by the fact that it does not give chlorine peroxide when
treated with concentrated sulphuric acid, and that it is not reduced
by sulphurous acid. The salts of the acid are known as the
_perchlorates_, and are all soluble in water; the potassium and
rubidium salts, however, are only soluble to a slight extent.
Potassium perchlorate, KClO4, can be obtained by carefully heating the
chlorate until it first melts and then nearly all solidifies again.
The fused mass is then extracted with water to remove potassium
chloride, and warmed with hydrochloric acid to remove unaltered
chlorate, and finally extracted with water again, when a residue of
practically pure perchlorate is obtained. The alkaline perchlorates
are isomorphous with the permanganates.

CHLORITE, a group of green micaceous minerals which are hydrous silicates of aluminium, magnesium and ferrous iron. The name was given by A.G. Werner in 1798, from [Greek: chlôritis], "a green stone." Several species and many rather ill-defined varieties have been described, but they are difficult to recognize. Like the micas, the chlorites (or "hydromicas") are monoclinic in crystallization and have a perfect cleavage parallel to the flat face of the scales and plates. The cleavage is, however, not quite so prominent as in the micas, and the cleavage flakes though pliable are not elastic. The chlorites usually occur as salt (H=2-3) scaly aggregates of a dark-green colour. They vary in specific gravity between 2.6 and 3.0, according to the amount of iron present. Well-developed crystals are met with only in the species clinochlore and penninite; those of the former are six-sided plates and are optically biaxial, whilst those of the latter have the form of acute rhombohedra and are usually optically uniaxial. The species prochlorite and corundophilite also occur as more or less distinct six-sided plates. These four better crystallized species are grouped together by G. Tschermak as orthochlorites, the finely scaly and indistinctly fibrous forms being grouped by the same author as leptochlorites.

Chemically, the chlorites are distinguished from the micas by the presence of a considerable amount of water (about 13%) and by not containing alkalis; from the soft, scaly, mineral talc they differ in containing aluminium (about 20%) as an essential constituent. The magnesia (up to 36%) is often in part replaced by ferrous oxide (up to 30%), and the alumina to a lesser extent by ferric oxide; alumina may also be partly replaced by chromic oxide, as in the rose-red varieties kämmererite and kotschubeite. The composition of both clinochlore and penninite is approximately expressed by the formula H8(Mg,Fe)5Al2Si3O18, and the formulae of prochlorite and corundophilite are H40(Mg,Fe)23Al14Si13O90 and H20(Mg,Fe)20Al8Si6O45 respectively. The variation in composition of these orthochlorites is explained by G. Tschermak by assuming them to be isomorphous mixtures of H4Mg3Si2O9 (the serpentine molecule) and H4Mg3Al2SiO9 (which is approximately the composition of the chlorite amesite). The leptochlorites are still more complex, and the intermixture of other fundamental molecules has to be assumed; the species recognized by Dana are daphnite, cronstedtite, thuringite, stilpnomelane, strigovite, diabantite, aphrosiderite, delessite and rumpfite.

The chlorites usually occur as alteration products of other minerals, such as pyroxene, amphibole, biotite, garnet, &c., often occurring as pseudomorphs after these, or as earthy material filling cavities in igneous rocks composed of these minerals. Many altered igneous rocks owe their green colour to the presence of secondary chlorite. Chlorite is also an important constituent of many schistose rocks and phyllites, and of chlorite-schist it is the only essential constituent. Well-crystallized specimens of the species clinochlore are found with crystals of garnet in cavities in chlorite-schist at Achmatovsk near Zlatoust, in the Urals, and at the Ala valley near Turin, Piedmont; also as large plates at West Chester in Pennsylvania and at other American localities. Crystals of penninite are found in serpentine at Zermatt in Switzerland and in the green schists of the Zillerthal in Tirol.

Closely allied to the chlorites is another group of micaceous minerals known as the vermiculites, which have resulted by the alteration of the micas, particularly biotite and phlogopite. The name is from the Latin _vermiculor_, "to breed worms," because when heated before the blowpipe these minerals exfoliate into long worm-like threads. They have the same chemical constituents as the chlorites, but the composition is variable and indefinite, varying with that of the original mineral and the extent of its alteration. Several indistinct varieties have been named, the most important of which is jeffersonite. (L. J. S.)