atomic See also:

• WEIGHT

weight 40.0 See also:

• atomic weight 40.0 CALCIUM [symbol Ca (o= x6)]

CALCIUM [See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol Ca (o= x6)]  , a metallic chemical See also:

• ELEMENT (Lat. elementum)

element, so named by See also:

• SIR

Sir See also:

• HUMPHRY, OZIAS (1742-1810)

Humphry See also:

• DAVY, SIR HUMPHRY

Davy from its occurrence in See also:

• CHALK

chalk (Latin calx) . It does not occur in nature in the See also:

• FREE

free See also:

• STATE
• STATE, GREAT OFFICERS OF

state, but in See also:

• COMBINATION (Lat. combinare, to combine)

combination it is widely and abundantly diffused . Thus the sulphate constitutes the minerals See also:

• ANHYDRITE

anhydrite, See also:

• ALABASTER
• ALABASTER, or ARBLASTIER, WILLIAM (1567-1640)

alabaster, See also:

• GYPSUM

gypsum, and selenite; the carbonate occurs dissolved in most natural See also:

• WATERS, TERRITORIAL

waters and as the minerals chalk, See also:

• MARBLE (from Lat. marmor, Gr. pApµapos, shining stone)

marble, See also:

• CALCITE

calcite, See also:

• ARAGONITE

aragonite; also in the See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double See also:

• CARBONATES

carbonates such as See also:

• DOLOMITE

dolomite, See also:

• BROMLITE

bromlite, See also:

• BARYTOCALCITE

barytocalcite; the fluoride as fluorspar; the fluophosphate constitutes the See also:

• MINERAL

mineral See also:

• APATITE

apatite; while all the more important mineral silicates contain a proportion of this element . Extraction.—See also:

• CALCIUM [symbol Ca, atomic weight 40.0 (o= x6)]

Calcium See also:

• OXIDE

oxide or See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime has been known from a very remote See also:

• PERIOD
• PERIOD (Gr. irepioSos, a going or way round, circuit, aepi, round, and &Sis, way, road)

period, and was for a See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time considered to be an elementary or undecomposable See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth . This view was questioned in the 18th See also:

• CENTURY (from Lat. centuria, a division of a hundred men)

century, and in 18o8 Sir Humphry Davy (Phil . Trans., 1808, p . 303) was able to show that lime was a combination of a See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal and See also:

• OXYGEN (symbol 0, atomic weight 16)

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 See also:

• ISOLATION

isolation of the metals See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium and See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium by the See also:

• ELECTROLYSIS (formed from Gr. Xbety, to loosen)

electrolysis of their hydrates, attempted to decompose a mixture of lime and mercuric oxide by the electric current; an See also:

• AMALGAM

amalgam of calcium was obtained, but the separation of the See also:

• MERCURY
• MERCURY (MERCU1uus)
• MERCURY (symbol Hg, atomic weight = 2oo)

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 . See also:

• BUNSEN, CHRISTIAN CHARLES JOSIAS, BARON VON (1791-186o,)
• BUNSEN, ROBERT WILHELM VON (1811-1899)

Bunsen (See also:

• ANN

Ann., 1854, 92, p . 248) was more successful when he electrolysed calcium chloride moistened with hydrochloric See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid; and A .

Matthiessen (Jour . Chem . See also:

• SOC

Soc., 1856, p . 28) obtained the metal by electrolysing a mixture of fused calcium and sodium chlorides . See also:

• HENRI

Henri See also:

• MOISSAN, HENRI (1852-1907)

Moissan obtained the metal of 99% purity by electrolysing calcium iodide at a See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low red See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat, using a See also:

• NICKEL
• NICKEL (symbol Ni, atomic weight 58.68 (0=16))

nickel See also:

• CATHODE

cathode and a See also:

• GRAPHITE

graphite anode; he also showed that a more convenient See also:

• PROCESS

process consisted in See also:

• HEATING

heating the iodide with an excess of sodium, forming an amalgam of the product, and removing the sodium by means of See also:

• ABSOLUTE (Lat. absolvere, to loose, set free)

absolute See also:

• ALCOHOL

alcohol (which has but little See also:

• ACTION

action on calcium), and the mercury by See also:

• DISTILLATION (from the Lat. distillare, more correctly destillare, to drop or trickle down)

distillation . The electrolytic isolation of calcium has been carefully investigated, and this is the method followed for the commercial See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of the metal . In 1902 W . Borchers and L . Stockem (Zeil. See also:

• FUR (connected with O. Fr. forre, a sheath or case; so " an outer covering ")

fur Eleclrochemie, 1902, p . 8757) obtained the metal of 90 % purity by electrolysing calcium chloride at a temperature of about 780°, using an See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron cathode, the anode being the graphite See also:

• VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel in which the electrolysis was carried out . In the same See also:

• YEAR

year, O . See also:

• RUFF

Ruff and W .

See also:

• PLATO

Plato (Ber . 1902, 35, p . 3612) employed a mixture of calcium chloride (too parts) and fluorspar (16.5 parts), which was fused in a See also:

• PORCELAIN

porcelain crucible and electrolysed with a See also:

• CARBON (symbol C, atomic weight 12)

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 See also:

• SALT (a common Teutonic word, cf. Dutch zout, Ger. Salz, Scand. salt; cognate with Gr. &Xs, Lat. sal)
• SALT, SIR TITUS, BART

salt with fluorspar, in a graphite vessel which serves as the anode . The cathode consists of an iron See also:

• ROD (O.E. rodd, probably related to Norw. rudda, stick, rodda, stake)
• ROD, EDOUARD (1857-1910)

rod which can be gradually raised . On electrolysis a layer of metallic calcium is formed at the See also:

• LOWER

lower end of this rod on the See also:

• SURFACE

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 See also:

• FORM (Lat. forma)

form in which calcium is put on the See also:

• MARKET (Lat. mercatus, trade or place of trade)

market . An See also:

• IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea as to the advance made by this method is recorded in the variation in the See also:

• PRICE
• PRICE, BARTHOLOMEW (1818–1898)
• PRICE, BONAMY (1807-1888)
• PRICE, RICHARD (1723-1791)

price of calcium . At the beginning of 1904 it was quoted at 5s. per See also:

• GRAM

gram, £250 per kilogram or £110 per See also:

• POUND
• POUND (2)—(a)

pound; about a year later the price was reduced to 21S. per kilogram, or I 2S. per kilogram in quantities of too kilograms .

These quotations apply to See also:

• GERMANY
• GERMANY (Ger. Deutschland)

Germany; in the See also:

• UNITED

United See also:

• KINGDOM

Kingdom the price (1905) varied from 27s. to 30S. per kilogram (12s. to 13S. per lb.) . See also:

• PRO

Pro perties.—A freshly prepared surface of the metal closely resembles See also:

• ZINC

zinc in See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance, but op exposure to the See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air it rapidly tarnishes, becoming yellowish and ultimately See also:

• GREY, CHARLES GREY, 2ND EARL (1764-1845)
• GREY, HENRY GREY, 3RD EARL (1802-1894)
• GREY, LADY JANE (1537-1554)
• GREY, SIR EDWARD
• GREY, SIR GEORGE (1812–1898)

grey or See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white in See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour owing to the formation of a surface layer of calcium See also:

• HYDRATE

hydrate . A faint See also:

• SMELL (connected etymologically with " smoulder " and " smoke ")

smell of See also:

• ACETYLENE

acetylene may be perceived during the oxidation in moist air; this is probably due to traces of .calcium See also:

• CARBIDE

carbide . It is rapidly acted on by See also:

• WATER

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 See also:

• BARIUM (symbol Ba, atomic weight 137'37 [0=16])

barium and See also:

• STRONTIUM [Symbol Sr, atomic weight 87.62 (0=16)]

strontium, and to some degree See also:

• MAGNESIUM [symbol Mg, atomic weight 24.32 (0 = 16)]

magnesium; these four elements comprise the so-called metals of the " alkaline earths." It combines directly with most elements, including See also:

• NITROGEN [symbol N., atomic weight 14.01, 0=16]

nitrogen; this can be taken See also:

• ADVANTAGE

advantage of in forming almost a perfect vacuum, the oxygen combining to form the oxide, CaO, and the nitrogen to form the nitride, Ca3N2 . Several of its See also:

• PHYSICAL

physical properties have been determined by K . See also:

• ARNDT, ERNST MORITZ (1769-1860)
• ARNDT, JOHANN (1555-1621)

Arndt (Ber., 1904, 37, p . 4733) . The metal as prepared by electrolysis generally contains traces of See also:

• ALUMINIUM (symbol Al; atomic weight 27.0)

aluminium and See also:

• SILICA

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 See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen, appears in See also:

• COMMERCE
• COMMERCE (Lat. commercium, from, cum, together, and rnerx, merchandise)

commerce under the name hydrolite .

Water decomposes it to give hydrogen free from See also:

• AMMONIA (NH3)

ammonia and acetylene, i gram yielding about 'co See also:

• COS
• COS, or STANKO (Ital. Stanchio, Turk. Islan-keui, by corruption from Etc rav KW)

cos. of See also:

• GAS

gas (Prats Aymerich, Abst . J . C . S., 1907, ii p . 460) . Calcium forms two oxides —the monoxide, CaO, and the dioxide, CaO, . The monoxide and its hydrate are more familiarly known as lime (q.v.) and slaked-lime . The dioxide was obtained as the hydrate, CaO2.8H2O, by P . See also:

• THENARD, LOUIS JACQUES (1777-1857)

Thenard (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, See also:

• PALE (through Fr. pal, from Lat. palms, a stake, for paglus, from the stem pag- of pangere, to fix; " pole " is from the same original source)

pale See also:

• BUFF (from Fr. bu.ffie, a buffalo)

buff-coloured See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder, very sparingly soluble in water . It is used as an antiseptic and oxidizing See also:

• AGENT (from Lat. agere, to act)

agent . Whereas calcium chloride, bromide, and iodide are deliquescent solids, the fluoride is practically insoluble in water; this is a See also:

• PARALLELISM, PSYCHOPHYSICAL

parallelism to the soluble See also:

• SILVER

silver fluoride, and the insoluble chloride, bromide and iodide . Calcium fluoride, CaF2, constitutes the mineral fluor-spar (q.v.), and is prepared artificially as an insoluble white powder by precipitating a See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of calcium chloride with a soluble fluoride . One See also:

• PART

part dissolves in 26,000 parts of water . Calcium chloride, CaC12, occurs in many natural waters, and as a by-product in the manufacture of carbonic acid (carbon dioxide), and potassium chlorate . Aqueous solutions See also:

• DEPOSIT (Lat. depositurn, from deponere, to lay down, to put in the care of)

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 See also:

• ALCOHOLS
• ALCOHOLS, ALDEHYDES AND
• ALCOHOLS, BENZYL ALCOHOL, BUTYL ALCOHOLS, METHYL ALCOHOL

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 io parts of the hexahydrate with 7 parts of See also:

• SNOW (in O. Eng. sndw; a common Indo-European word; cf. in Teutonic languages, Ger. Schnee, Du. sneeuw; in Slavonic snieg', Lith. snegas; Gr. vi4a, Lat. nix, nivis, whence the Romanic forms, Ital. neve, Fr. neige, &c.; Ir. and Gael. sneachd; the original

snow . A saturated solution of calcium chloride contains 325 parts of CaCl2 to too 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 " See also:

• BLEACHING

bleaching powder " is a calcium chlorhypochlorite or an equimolecular mixture of the chloride and hypochlorite (see See also:

• ALKALI

ALKALI MANUFACTURE and BLEACHING) . Calcium carbide, CaC2, a See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound of See also:

• GREAT

great See also:

• INDUSTRIAL

industrial importance as a source of acetylene, was first prepared by F . See also:

• WOHLER, FRIEDRICH (1800-1882)

Wohler . It is now manufactured by heating lime and carbon in the electric See also:

• FURNACE

furnace (see ACETYLENE) . Heated in See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine or with See also:

• BROMINE (symbol Br, atomic weight 79-96)

bromine, it yields carbon and calcium chloride or bromide; at a dull red heat it See also:

• BURNS, JOHN (1858– )
• BURNS, ROBERT (1759-1796)
• BURNS, SIR GEORGE

burns in oxygen, forming calcium carbonate, and it becomes incandescent in See also:

• SULPHUR

sulphur vapour at 500°, forming calcium sulphide and carbon disulphide . Heated in the electric furnace in a current of air, it yields calcium See also:

• CYANAMIDE

cyanamide (see CYANAMIDE) . Calcium carbonate, CaCO3, is of exceptionally wide See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution in both the mineral and See also:

• ANIMAL
• ANIMAL (Lat. animalis, from anima, breath, soul)

animal kingdoms . It constitutes the bulk of the chalk deposits and See also:

• LIMESTONE

limestone rocks; it forms over one-See also:

• HALF

half of the mineral dolomite and the See also:

• ROCK
• ROCK (O.Fr. rake, Sp. rota, Ital. rocca; possibly from a Lat. form rupica, from rupes, rock)
• ROCK, DANIEL (1799–187t)

rock magnesium limestone; it occurs also as the dimorphous minerals aragonite (q.v.) and calcite (q.v.) . See also:

• TUFF (Ital. tufo)

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 See also:

• CAVE (Lat. cavea, from caves, hollow)
• CAVE, EDWARD (1691–1754)
• CAVE, WILLIAM (1637–1713)

cave, in the formation of See also:

• STALACTITES (Gr. (rraXaicros, from vraXaQVecv, to drip)

stalactites and stalagmites .

In the animal kingdom it occurs as b4~th calcite and aragonite in the tests of the See also:

• FORAMINIFERA

foraminifera, echinoderms, See also:

• BRACHIOPODA

brachiopoda, and See also:

• MOLLUSCA

mollusca; also in the skeletons of See also:

• SPONGES

sponges and See also:

• CORALS (KoRAis), ADAMANTIOS [in French, DIAMANT CORAY] (1748–1833)

corals . Calcium carbonate is obtained as a white precipitate, almost insoluble in water (I part requiring io,000 of water for solution), by mixing solutions of a carbonate and a calcium salt . Hot or dilute See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold solutions deposit See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute orthorhombic crystals of aragonite, cold saturated or moderately strong solutions, hexagonal (See also:

• RHOMBOHEDRAL

rhombohedral) crystals of calcite . Aragonite is the least See also:

• STABLE

stable form; crystals have been found altered to calcite . Calcium nitride, Ca,N2, is a greyish-yellow powder formed by heating calcium in air or nitrogen; water decomposes it with See also:

• EVOLUTION

evolution of ammonia (see H . Moissan, Comp' . Rend., 127, p . 497) . Calcium nitrate, Ca(NO,)2.4H2O, is a highly deliquescent salt, crystallizing in.See also:

• MONOCLINIC

monoclinic prisms, and occurring in various natural waters, as an efflorescence in limestone caverns, and in the See also:

• NEIGHBOUR (O. Eng. neahgebiir, from Walt, " nigh," " near ")

neighbour-See also:

• HOOD,
• HOOD, JOHN BELL (1831–1879)
• HOOD, SAMUEL HOOD, VISCOUNT (1724–1816)
• HOOD, SIR SAMUEL (1762-1814)
• HOOD, THOMAS (1799-1845)
• HOOD, TOM (1835–1874)

hood of decaying nitrogenous organic See also:

• MATTER

matter . Hence its synonyms, " See also:

• WALL (O. Eng. weal, weall, Mid. Eng. wal, wane, adapted from Lat. vallum, rampart; the original O. Eng. word for a wall was wag or tenth)
• WALL, RICHARD (1694-1778)

wall-See also:

• SALTPETRE (from the Lat. sal, salt, Petra, a rock)

saltpetre " and " lime-saltpetre "; from its disintegrating action on See also:

• MORTAR

mortar, it is sometimes referred to as " saltpetre rot.' The anhydrous nitrate, obtained by heating the crystallized salt, is very phosphorescent, and constitutes " Baldwiq's See also:

• PHOSPHORUS (Gr. 4ws, light, sPEpety, to bear)

phosphorus." A bask nitrate, Ca(NO3)2•Ca(OH)2.3H20; is obtained by dissolving calcium hydroxide in a solution of the normal nitrate . Calcium phosphide, Ca3P2, 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 See also:

• SIGNAL

signal See also:

• FIRE (in O. Eng. f j'r; the word is common to West German languages, cf. Dutch vuur, Ger. Feuer; the pre-Teutonic form is seen in Sanskrit pu, pavaka, and Gr. irup; the ultimate origin is usually taken to be a root meaning to purify, cf. Lat. purus)

fire (" See also:

• HOLMES, OLIVER WENDELL (18o9-1894)

Holmes See also:

• LIGHTS, CEREMONIAL USE OF

lights "), (see L .

Gattermann and W . Haussknecht, Ber., 189o, 23, p . 1176, and H . Moissan, Compt . Rend., 128, p . 787) . Of the calcium orthophosphates, the normal salt, Ca3(PO4)27 is the most important . It is the See also:

• PRINCIPAL

principal inorganic constituent of bones, and hence of the " See also:

• BONE (a word common in various forms to Teutonic languages, in many of which it is confined to the shank of the leg, as in the German Bein)
• BONE, HENRY (1755-1834)

bone-ash " of commerce (see PHOSPHORUS) ; it occurs with fluorides in the mineral apatite (q.v.) ; and the concretions known as See also:

• COPROLITES (from Gr. KInrpos, dung, and X10os, stone)

coprolites (q.v.) largely consist of this salt . It also constitutes the minerals ornithite, Caa(PO4)2.2H20, osteolite and sombrerite . The mineral brushite, CaHPO4.2H2O, which is isomorphous with the acid arsenate pharmacolite, CaHAsO4.2H20, 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, Ca2P2O7, with water under pressure .

It is insoluble in water; slightly soluble in solutions of carbonic acid and See also:

• COMMON

common salt, and readily soluble in concentrated hydrochloric and nitric acid . Of the acid orthophosphates, the mono-calcium salt, CaH4(PO4)2, may be obtained as crystalline scales, containing one See also:

• MOLECULE (from mod. Lat. molecula, the diminutive of moles, a mass)

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, Ca2H2(PO4)2, occurs in a concretionary form in the ureters and See also:

• CLOACA

cloaca of the See also:

• STURGEON (Acipenser)

sturgeon, and also in See also:

• GUANO (a Spanish word from the Peruvian huanu, dung)

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 See also:

• PHOSPHATES

phosphates are also known . Calcium monosulphide, CaS, a white amorphous powder, sparingly soluble in water, is formed by heating the sulphate with See also:

• CHARCOAL

charcoal, or by heating lime in a current of sulphuretted hydrogen . It is particularly noteworthy from the See also:

• PHOSPHORESCENCE

phosphorescence which it exhibits when heated, or after exposure to the See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun's rays; hence its synonym " See also:

• CANTON
• CANTON (borrowed from the Ital. cantone, a corner or angle)
• CANTON (more correctly KWANG-CHOW Fu)
• CANTON, JOHN (1718-1772)

Canton's phosphorus," after See also:

• JOHN
• JOHN (1167–1216)
• JOHN (1290-c. 1320)
• JOHN (1296-1346)
• JOHN (1371–1419)
• JOHN (1468-1532)
• JOHN (1801-1873)
• JOHN (Heb. llni')
• JOHN (ZAPOLYA) (1487-1540)
• JOHN, 4TH MARQUESS OF TWEEDDALE (c. 1695-1762)
• JOHN, DON (1545-1578)
• JOHN, DON (1629–1679)
• JOHN, GOSPEL OF ST
• JOHN, or HAYS (1513–1571)
• JOHN, THE APOSTLE
• JOHN, THE EPISTLES OF

John Canton (1718-1772), an See also:

• ENGLISH

English natural philosopher . The sulpliydrate or hydrosulphide, Ca(SH)2, is obtained as colourless, prismatic crystals of the See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition Ca(SH)2.6H20, by passing sulphuretted hydrogen into See also:

• MILK (0. Eng. meoluc; from a common Indo-European root, cf. Lat. mulgere, Gr. ?t dXyetv)

milk of lime . The strong aqueous solution deposits colourless, four-sided prisms of the hydroxy-hydrosulphide, Ca(OH)(SH) .

The disulphide, CaS2, and pentasulphide, CaSSi are formed when milk of lime is boiled with See also:

• FLOWERS, ARTIFICIAL

flowers of sulphur . These sulphides form the basis of See also:

• BALMAIN

Balmain's luminous paint . An oxysulphide, 2CaS•CaO, is sometimes See also:

• PRESENT

present in " soda-See also:

• WASTE (O. Fr. wast, guast, gast, gaste; Lat. vastus, vast, desolate)

waste," and See also:

• ORANGE
• ORANGE (Citrus Aurantium)
• ORANGE, HOUSE OF

orange-coloured, acicular crystals of 4CaS•CaSO4.18H2O occasionally See also:

• SETTLE
• SETTLE, ELKANAH (1648–1724)

settle out on the long See also:

• STANDING

standing of oxidized " soda- or alkali-waste " (see ALKALI MANUFACTURE) . Calcium sulphite, CaSO3, 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 See also:

• WOOD, ANTHONY A2 (1632-1695)
• WOOD, JOHN GEORGE (1827—1889)
• WOOD, MRS HENRY [ELLEN] (1814—1887)
• WOOD, SEARLES VALENTINE (1798—188o)

wood-pulp for See also:

• PAPER
• PAPER (Fr. papier, from Lat. papyrus)

paper making . Calcium sulphate, CaSO4, constitutes the minerals anhydrite (q.v.), and, in the hydrated form, selenite, gypsum (q.v.), alabaster (q.v.), and also the adhesive See also:

• PLASTER

plaster of See also:

• PARIS
• PARIS (also called ALEXANDROS)
• PARIS, ALEXIS PAULIN (1800-x881)
• PARIS, BRUNO PAULIN GASTON (1839-1903)
• PARIS, FRANCOIS DE (169o-1727)
• PARIS, LOUIS PHILIPPE ALBERT
• PARIS, TREATIES OF (1814-1815)

Paris (see See also:

• CEMENT (from Lat. caementum, rough pieces of stone, a shortened form of caedimentum, from caedere, to cut)

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 (Too 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, CaSiO3, occurs in nature as mono-clinic crystals known as See also:

• TABULAR

tabular spar or See also:

• WOLLASTONITE

wollastonite; it may be prepared artificially from solutions of calcium chloride and sodium silicate . H . Le Chatelier (Annales See also:

• DES

des mines, 1887, p . 345) has obtained artificially the compounds: CaSiO3, Ca2SiO4, Ca3Si2O7, and CasSiOs .

(See also G . Oddo, Chemisches Centralblatt, 1896, 228.) Acid calcium silicates are represented in the mineral kingdom by gyrolite, H2Ca2(SiO3)3•See also:

• H2O (combined)

H2O, a lime zeolite, sometimes regarded as an altered form of See also:

• APOPHYLLITE

apophyllite (q.v.), which is itself an acid calcium silicate containing an alkaline fluoride, by okenite, H2Ca(SiO0)2•H2O, and by xonalite 4CaSiO3•H2O . Calcium silicate is also present in the minerals: See also:

• OLIVINE

olivine, pyroxenes, amphiboles, See also:

• EPIDOTE

epidote, felspars, See also:

• ZEOLITES

zeolites,to a Bunsen See also:

• FLAME (Lat. flamma; the root flag- appears in flagrare, to burn, blaze, and Gr. d, XEryew)

flame, which when viewed through See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass appears to be See also:

• FINCH
• FINCH (Ger. Fink, Lat. Fringilla)

finch-green; this distinguishes it in the presence of strontium, whose See also:

• CRIMSON

crimson coloration is See also:

• APT

apt to See also:

• MASK (Fr. masque, apparently from med. Lat. mascus, masca, spectre, through Ital. maschera, Span. mascara)

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 See also:

• LINE

line (a), (X 6163), a green line (3), (X 4229), and a fainter See also:

• INDIGO (earlier indico, from Lat. indicum, the Indian sub-stance or dye; the Sans. name was niti, from nila, dark blue, and this through Arab. al-nil, annil, gives " aniline ")

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 .