See also:diamond (q.v.),
See also:graphite (q.v.), as a constituent of all animal and
See also:vegetable tissues and of
See also:coal and petroleum . It also enters (as
See also:carbonates) into the composition of many minerals, such as
See also:dolomite, 306
See also:calamine and spathic iron ore . In combination with
See also:oxygen (as
See also:carbon dioxide) it is also found to a small extent in the atmosphere . It is a solid substance which occurs in several modifications, differing very much in their
See also:physical properties . Amorphous carbon is obtained by the destructive
See also:distillation of many carbon compounds, the various kinds differing very greatly as regards physical, characters and purity, according to the substance used for their preparation . The most
See also:common varieties met with are lampblack,
See also:gas carbon,
See also:charcoal, animal charcoal and
See also:coke . Lampblack is prepared by burning
See also:turpentine and other substances
See also:rich in carbon, with a limited supply of air; the products of combustion being conducted into condensing
See also:chambers in which cloths are suspended, on which the carbon collects . It is further purified by
See also:heating in closed vessels, but even then it still contains a certain amount of
See also:matter and more or less
See also:hydrocarbons . It is used in the manufacture of printer's
See also:ink, in the preparation of black paint and in
See also:calico printing . Gas carbon is produced by the destructive distillation of coal in the manufacture of
See also:illuminating gas (see Gas: Manufacture), being probably formed by the decomposition of gaseous hydrocarbons . It is a very dense
See also:form of carbon, and is a
See also:good conductor of
See also:heat and
See also:electricity .
It is used in the manufacture of carbon rods for arc
See also:lights, and for the negative
See also:element in the
See also:Bunsen battery . Charcoal is a porous form of carbon; several varieties exist .
See also:Sugar charcoal is obtained by the carbonization of sugar . It is purified by boiling with acids, to remove any mineral matter, and is then ignited for a long
See also:time in a current of chlorine in
See also:order to remove the last traces of hydrogen . Animal charcoal (
See also:bone black) is prepared by charring bones in iron retorts . It is a very impure form of carbon, containing on the
See also:average about 8o%, of calcium phosphate . It possesses a much greater decolorizing and absorbing power than wood charcoal . A variety of animal charcoal is sometimes prepared by calcining fresh
See also:blood with potassium carbonate in large cylinders, the mass being purified by boiling out with dilute hydrochloric acid and subsequent reheating . Wood charcoal is a hard and brittle black substance, which retains the
See also:external structure of the wood from which it is made . It is prepared (where wood is plentiful) by stacking the wood in heaps, which are covered with
See also:earth or with brushwood and
See also:turf, and then burning the heap slowly in a limited supply of air . The combustion of the wood is conducted from the top downwards, and from the exterior towards the centre;
See also:great care has to be taken that the
See also:process is carried out slowly . The disadvantage in this process is that the by-products, such as pyroligneous acid,
See also:acetone, wood spirit, &c., are lost; as an alternative method, wood is frequently carbonized in ovens or retorts and the volatile products are condensed and utilized .
Charcoal varies considerably in its properties, depending upon the particular variety of wood from which it is prepared, and also upon the process used in its manufacture . It can be made at a temperature aslow as 300° C., and is then a soft, very friable material possessing a low ignition point . When made at higher temperatures it is much more dense, and its ignition point is considerably higher . Charcoal burns when heated in air, usually without the formation of flame, although a flame is apparent if the temperature be raised . It is characterized by its power of absorbing gases; thus, according to J .
See also:Hunter [Phil . Mag., 1863 (4), 25, p . 3631, one
See also:volume of charcoal absorbs (at o° C. and 76o mm. pressure) 171.7 res. of
See also:ammonia, 86.3 ccs. of nitrous
See also:oxide, 67.7 ccs. of carbon monoxide, 21.2 ccs. of carbon dioxide, 17.9 ccs. of oxygen, 15.2 ccs. of nitrogen, and 4.4 ccs. of hydrogen [see also J .
See also:Ann . Chim . Phys., 1904 (8), 3, p . 51 .
It also has the power of absorbing colouring matters fromsolution . Charcoal is used as a fuel and as a reducing
See also:agent in metallurgical processes . The element carbon unites directly with hydrogen to form
See also:acetylene when an electric arc is passed between carbon poles in an atmosphere of hydrogen (M . Berthelot) ; it also unites directly with fluorine, producing, chiefly, carbon tetrafluoride CF4 . It burns when heated in an atmosphere of oxygen, forming carbon dioxide, and when heated in
See also:sulphur vapour it forms carbon bisulphide (q.v.) . When heated with nitrogenous substances, in the presence of carbonated or
See also:alkali, it forms cyanides . It combines directly with silicon, at the temperature of the electric
See also:furnace, yielding
See also:carborundum, SiC; and H .
See also:Moissan has also shown that it will combine withmany metals at the temperature of the electric furnace, to form carbides (q.v.) . The specific heat of carbon varies with the temperature the following values having been obtained by H . F . Weber (Jahresberichte, 1874, p . 63): Diamond .
Graphite . Porous wood carbon . t° . Sp . Ht . t° . Sp . Ht. t° . Sp . Ht . -50.5 0.0635 -50.3 0.1138 0-23 0.1653 - to-6 0.0955 -10.7 0.1437 0-99 0'1935 +10.7 0.1128 +Io.8 0.1604 0—223 0.2385 85.5 0.1765 61.3 0.1990 206.1 0.2733 201.6 0.2966 606.7 0.4408 641'9 0'4454 985.0 0'4589 977.0 0.4670 The atomic
See also:weight of carbon has been determined by J . B . A .
See also:Dumas and by J . S .
See also:Stas [Ann . Chico . Phys., 1841 (3), 1, p . 1 ; Jahresb., 1849, 2231 by estimating the amount of carbon dioxide formed on burning graphite or diamond in a current of oxygen, the value obtained being 12.0 (o =16) . Confirmatory evidence has also been obtained by 0 . L . Erdmann and R . F . Marchand (Jour . Prak .
Chem., 1841, 23, p . 159; see also F . W .
See also:Clarke, Jahresb., 1881, p . 7) . Compounds.—Three oxides of carbon are known, namely, carbon suboxide, C302, carbon monoxide, CO, and carbon dioxide,
See also:CO2 . Carbon suboxide, C202, is formed by the
See also:action of phosphorus pent-oxide on
See also:ethyl malonate (0 . Diels and B .
See also:Wolf, Bee., 1906, 39, p . 689), CH2(000C2H5)2=2C2H4+2H2O+C3O2 . At ordinary temperatures it is a colourless gas, possessing a penetrating and suffocating smell . It liquefies at 7° C .
It is an exceedingly reactivecompound, combining with
See also:water to form malonic acid, with hydrogen chloride to form malonyl chloride, and with ammonia to form malonamide . When kept for some time in sealed tubes it changes to a yellowish liquid, from which a yellow flocculent substance gradually separates, and finally it suddenly solidifies to a dark red mass, which appears to be a polymeric form . Its vapour
See also:density agrees with the molecular
See also:formula C3O2, and this formula is also confirmed by exploding the gas with oxygen and measuring the amount of carbon dioxide produced (see
See also:KETENES) . Carbon monoxide, CO, is found to some extent in volcanic gases . It was first prepared in 1776 by J . M . F . Lassone (Mem . Acad .
See also:Paris) by heating
See also:zinc oxide with carbon, and was for some time considered to be identical with hydrogen .
See also:Cruikshank concluded that it was are. oxide of carbon, a fact which was confirmed by
See also:Clement and J . B .
Desormes (Ann . Chico . Phys., 18oi, 38, p . 285) . It may be prepared by passing carbon dioxide over red-hot carbon, or red-hot iron; by heating carbonates (
See also:magnesite, chalk, &c.) with zinc dust or iron; or by heating many metallic oxides with carbon . It may also be prepared by heating formic and oxalic acids (or their salts) with concentrated sulphuric acid (in the case of oxalic acid, an equal volume of carbon dioxide is produced) ; and by heating potassium ferrocyanide with a large excess of concentrated sulphuric acid, K4Fe (C N )s +6H2SO4 +6H2O = 2 K2SO4 +FeSO4 + 3(NH4)2SO4 +6C0 . It is a colourless, odourless gas of specific gravity 0.967 (air = I) . It is one of the most difficultly liquefiable gases, its critical temperature being -139.5° C., and its critical pressure 35'5 atmos . The liquid boils at -190° C., and solidifies at -211 ° C . (L . P . Cailletet, Comptes rendus, 1884, 99, p .
706) . It is only very slightly soluble in water . It burns with a characteristic
See also:pale blue flame to form carbon dioxide . It is very poisonous, uniting with the haemoglobin of the blood to form carbonyl-haemoglobin . It is a powerful reducing agent, especially at high temperatures . It is rapidly absorbed by an ammoniacal or acid (hydrochloric acid) solution of cuprous chloride . It unites directly with chlorine, forming carbonyl chloride or phosgene (see below), and with nickel and iron to form nickel and iron carbonyls (see NICKEL and IRON) . It also combines directly with potassium hydride to form potassium formate (see FoRMIC Am)) . The volume composition of carbon monoxide is established by exploding a mixture of the gas with oxygen, two volumes of the gas combining with one volume of oxygen to form two volumes of carbon dioxide . This fact, coupled with the determination of the vapour density of the gas, establishes the molecular formula CO . Carbon dioxide, CO2, is a gas first distinguished from air by
See also:van Helmont (1577—1644), who observed that it was formed in
See also:fermentation processes and during combustion, and gave to it the name gas sylvestre . J .
Black (Edin . Phys. and Lit . Essays, 1755) showed that it was a constituent of the carbonated alkalis and called it " fixed air." T . O .
See also:Bergman, in 1774, pointed out its acid character, and A . L . Lavoisier (1781—1788) first proved it to be an oxide of carbon by burning carbon in the oxygen obtained from the decomposition of mercuric oxide . It is a
See also:regular constituent of the atmosphere, and is found in many
See also:waters and in volcanic gases; it also occurs in the uncombined
See also:condition at the Grotto del
See also:Cane (Naples) and in the
See also:Poison Valley (
See also:Java) . It is a constituent of the minerals
See also:azurite, spathic iron ore, calamine,
See also:strontianite, witherite, calcite
See also:limestone, &c . It may be prepared by burning carbon in excess of air or oxygen, by the
See also:direct decomposition of many carbonates by heat, and by the decomposition of carbonates with mineral acids, M2CO2+2HC1=2MC1+
See also:H2O+CO2 . It is also formed in ordinary fermentation processes, in the combustion of all carbon compounds (oil, gas, candles, coal, &c.), and in the process of respiration . It is a colourless gas, possessing a faint pungent smell and a slightly acid taste .
It does not
See also:burn, and does not support ordinary combustion, but the alkali metals and magnesium, if strongly heated, will continue to burn in the gas with formation of oxides and liberation of carbon . Its specific gravity is 1.529 (air= I) . It is readily condensed, passing into the liquid condition at o° C. under a pressure of 35 atmospheres . Its critical temperature is 31.35° C., and its critical pressure is 72.9 atmos . The liquid boils at -78.2° C . (I atmo.), and by rapid evaporation can be made to solidify to a
See also:white solid which melts at—65° C . (see LIQUID GASES) . Carbon dioxide is moderately soluble in water, its coefficient of solubility at o° C. being 1.7977 (R . Bunsen) . It is still more soluble in
See also:alcohol . The solution of the gas in water shows a faintly acid reaction and is supposed to contain carbonic acid, H2CO8 . The gas is rapidly absorbed by solutions of the caustic alkalis, with the production of alkaline carbonates (q.v.), and it combines readily with potassium hydride to form potassium formate .
It unites directly with ammonia gas to form ammonium carbamate, NH2OOONH4 . It may be readily recognized by the white precipitate which it forms when passed throughlime or baryta water . Carbon dioxide dissociates, when strongly heated, into carbon monoxide and oxygen, the reaction being a balanced action; the extent of
See also:dissociation for varying temperatures and pressures has been calculated by H . Le Chatelier (Zeit . Phys . Chem., 1888, 2, p . 782; see H . Sainte-Claire Deville, Comptes rendus, 1863, 56, p . 195 et seq.) . The volume composition of carbon dioxide is determined by burning carbon in oxygen, when it is found that the volume of carbon dioxide formed is the same as that of the oxygen required for its production, hence carbon dioxide contains its own volume of oxygen . Carbon dioxide finds
See also:industrial application in the preparation of soda by the Solvay process, in the sugar
See also:industry, in the manufacture of mineral waters, and in the artificial production of ice . Carbonyl chloride (phosgene), COCl2, was first obtained by
See also:Davy (Phil .
Trans., 1812, 40, p . 220) . It may be prepared by the directunion of carbon monoxide and chlorine in sunlight (Th . Wilm and G . Wischin, Ann., 1868, 14, p . 150) ; by the action of phosphorus pentoxide on carbon tetrachloride at 200—210° C . (G . Gustayson, Ber., 1872, 5, . 30), 4CC14+P4010 =2CO2+4POCls+ 200012 ; by the oxidation of-
See also:chloroform with chromic acid mixture (A . Emmerlingg and B . Lengyel, Ber., 1869, 2, p . 54), 4CHC18+302 = 400012+2H2O+2C12; or most conveniently by heating carbon tetrachloride with fuming sulphuric acid (H .
Erdmann, Ber., 1893, 26, p . 1993), 2S02+CC14=S205C12+0001, . It is a colourless gas, possessing an unpleasant pungent smell . Its vapour density is 3.46 air =1) . It may be condensed to a liquid, which boils at 8° C . It is readily soluble in
See also:benzene, glacial acetic acid, and in many hydrocarbons . Water decomposes it violently, with formation of carbon dioxide and hydrochloric acid . It reacts with alcohol to form chlorcarbonic ester and ultimately diethyl carbonate (see CARBONATEs), and with ammonia it yields
See also:urea (q.v.) . It is employed commercially in the production of colouring matters (see
See also:BENZOPHENONE), and for various synthetic processes . Carbon oxysulphide, COS, was first prepared by C . Than in 1867 (Ann . Suppl., 5, p .
236) by passing carbon monoxide and sulphur vapour through a
See also:tube at a moderate heat . It is also formed by the action of sulphuretted hydrogen on the isocyanic
See also:esters, 2CONC2H6+H2S=COS+CO(NHC2H6)2, by the action of concentrated sulphuric acid on the isothiocyanie esters, RNCS+H20 = COS+RNH2, or of dilute sulphuric acid on the thiocyanates . In the latter reaction various other compounds, such as carbon dioxide, carbon bisulphide and hydrocyanic acid, are produced . They are removed by passing the vapours in succession through concentrated solutions of the caustic alkalis, concentrated sulphuric acid, and triethyl phosphine; the residual gas is then purified by liquefaction (W . Hempel, Zeit. angew . Chemie, 1901, 14, p . 865) . It is also formed when sulphur trioxide reacts with carbon bisulphide at ioo° C., CS2+3SO3 =COS+4SO2, and by the decomposition of ethyl potassium thiocarbonate with hydrochloric acid, CO(OC2H6)SK+ HCI=COS+KCI+C2H5OH . It is a colourless, odourless gas, which burns with a blue flame and is decomposed by heat . Its vapour density is 2.1046 (air =1) . The liquefied gas boils at -47° C. under atmospheric pressure . It is soluble in water; the aqueous solution gradually decomposes on
See also:standing, forming carbon dioxide and sulphuretted hydrogen .
It is easily soluble in solutions of the caustic alkalis, provided they are not too concentrated, forming solutions of alkaline carbonates and sulphides, COS+4KHO=K2CO5+ K2S-l- 2H2O .
CS2 CARBON BISULPHIDE
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