Carbonate Sentence Examples

Ammonium carbonate is added to the filtrate; this precipitates calcium, strontium and barium.

It dissolves easily in water, forming the hydrated chloride, CoC12.6H20, which may also be prepared by dissolving the hydroxide or carbonate in hydrochloric acid.

Obviously no more than this is possible until physiologists are able to state much more precisely than at present what is the influence of common salt on the plants of salt-marshes, of the action of calcium carbonate on plants of calcareous soils, and of the action of humous compounds on plants of fens and peat moors.

Cobalt fluoride, CoF 2.2H 2 0, is formed when cobalt carbonate is evaporated with an excess of aqueous hydrofluoric acid, separating in rose-red crystalline crusts.

Chemicals sulphate of copper, employed chiefly as a preventive 01 certain maladies of the vine; carbonate of lead, hyper.

Habitats rich in mineral salts, especially calcium carbonate, poor in acidic humous compounds, and characterized by ash woods, beech woods, and calcareous pasture.

Doubtless, the excess of any soluble mineral salt or salts interferes with the osmotic absorption of the roots; and although calcium carbonate is insoluble in pure water, it is slightly soluble in water containing carbon dioxide.

The insufficiency of this argument, however, is shown by the data for arsenious and antimonious oxides, and also for the polymorphs of calcium carbonate, the more symmetrical polymorphs having a lower density.

The disulphide, IrS2, is formed when powdered iridium is heated with sulphur and an alkaline carbonate.

The cobaltous salts are formed when the metal, cobaltous oxide, hydroxide or carbonate, are dissolved in acids, or, in the case of the insoluble salts, by precipitation.

It is also readily soluble in solutions of the caustic alkalis, slightly soluble in aqueous ammonia solution, and almost insoluble in sodium carbonate solution.

In this latter reaction the deep yellow solution obtained is exposed to air when the calcium polysulphide formed is gradually converted into thiosulphate by oxidation, and the calcium salt thus formed is converted into the sodium salt by sodium carbonate or sulphate.

The spa (saline and carbonate springs), specific in cases of feminine disorders, is visited by about 5000 patients annually.

It is probable that the limpet takes several years to attain full growth, and during that period it frequents the same spot, which becomes gradually sunk below the surrounding surface, especially if the rock be carbonate of lime.

Close to them is the remarkable dart-sac ps, a thick-walled sac, in the lumen of which a crystalline four-fluted rod or dart consisting of carbonate of lime is found.

In other slugs, namely, Limax and Anion, the shell-sac remains permanently closed over the shell-plate, which in the latter genus consists of a granular mass of carbonate of lime.

Many esters of malonic acid have been prepared, the most important being the diethyl ester (malonic ester), CH 2 (000C 2 H 5) 2, which is obtained by dissolving monochloracetic acid in water, neutralizing the solution with potassium carbonate, and then adding potassium cyanide and warming the mixture until the reaction begins.

Potash lyes also may be bought direct, but in some cases they are sharpened or causticized by the soap-boiler himself from the carbonate.

Phosphorus is obtained as a soluble phosphate (which can be examined in the usual way) by lixiviating the product obtained when the substance is ignited with potassium nitrate and carbonate.

Manasse (German patent 73,279) prepared an intimate mixture of phenol and potassium carbonate, which is then heated in a closed vessel with carbon dioxide, best at 130 -160 C. The Chemische Fabrik vorm.

The existence of sulphuretted hydrogen in great quantities below loo fathoms, the extensive chemical precipitation of calcium carbonate, the stagnant nature of its deep waters, and the absence of deep-sea life are conditions which make it impossible to discuss it along with the physical and biological conditions of the Mediterranean proper.

The foundation of the island is in many places almost pure carbonate of lime, and there are numerous small limekilns.

The 0-form is obtained by the direct action of hydroxylamine hydrochloride on mesityl oxide, the hydrochloride so formed being decomposed by sodium carbonate.

In de Lambilly's process air and steam is led over white-hot coke, and carbon dioxide or monoxide removed from the escaping gases according as ammonium formate or carbonate is wanted.

All of this is not available, for carbonic acid is present as such in solution, as bicarbonate (of magnesium mainly) and as normal carbonate.

That is, the concentration of H-ions decreases and that of the HO-ions increases; the water becomes more alkaline because the carbonic acid of the bicarbonate has been abstracted by the phytoplankton to the extent that normal carbonate is left.

All these animals have calcareous skeletons or shells of some form and they secrete the calcium from its solution as sulphate, converting it into carbonate.

It is not at all certain that the masses on which coral reefs are built consist entirely of the remains of the skeletons of reef-forming organisms and it is probable that chemically precipitated carbonate of lime predominates.

The water in shallow seas, off the shores of islands or in lagoons, is saturated with calcium bicarbonate and if the amount of carbonic acid in solution be reduced by any means, normal carbonate must be precipitated.

Therefore a reduction in the partial pressure of the gas in the atmosphere, or a rise in the temperature of the water, or a violent agitation of the sea itself, will lead to precipitation of calcium carbonate.

There are, therefore, a number of agencies, all of which operate in shoal waters on the lee side of islands, or in shallow lagoons in such regions as the Bahamas, and the result of all these is to throw down calcium carbonate from solution in sea-water as minute needle-shaped crystals or little balls of aragonite.

The liquid is now run into neutralizing tanks containing sodium carbonate, and, after settling, the supernatant liquid, termed "light liquor," is run through bag filters and then on to bone-char filters, which have been previously used for the "heavy liquor."

Before it is put in, the article is roughly put together, and the expansion of the included air forces the rubber into contact with the internal surface of the mould, or a little carbonate of ammonia is enclosed.

In order to make spongy or porous rubber, some material is incorporated which will give off gas or vapour at the vulcanizing temperature, - such as carbonate of ammonia, crystallized alum, and finely ground damp sawdust.

Klaproth in the mineral honeystone, which is the aluminium salt of the acid, The acid may be prepared by warming honeystone with ammonium carbonate, boiling off the excess of the ammonium salt and adding ammonia to the solution.

The native carbonate or cerussite (q.v.) occasionally occurs in the pure form, but more frequently in a state of intimate intermixture with clay ("lead earth," Bleierde), limestone, iron oxides, &c. (as in the ores of Nevada and Colorado), and some times also with coal ("black lead ore").

All native carbonate of lead seems to be derived from what was originally galena, which is always present in it as an admixture.

The use of the first two is restricted, as they are suited only for galena ores or mixtures of galena and carbonate, which contain not less than 58% lead and not more than 4% silica; further, ores to be treated in the ore-hearth should run low in or be free from silver, as the loss in the fumes is excessive.

When carbonic acid is present the dissolved oxide is soon precipitated as basic carbonate, so that the corrosion of the lead becomes continuous.

It is also obtained by passing chlorine into a suspension of lead oxide or carbonate, or of magnesia and lead sulphate, in water; or by treating the sesquioxide or red oxide with nitric acid.

The Kassner process for the manufacture of oxygen depends upon the formation of calcium plumbate, Ca2Pb04, by heating a mixture of lime and litharge in a current of air, decomposing this substance into calcium carbonate and lead dioxide by heating in a current of carbon dioxide, and then decomposing these compounds with the evolution of carbon dioxide and oxygen by raising the temperature.

Red lead or triplumbic tetroxide, Pb304, is a scarlet crystalline powder of specific gravity 8.6-9.1, obtained by roasting very finely divided pure massicot or lead carbonate; the brightness of the colour depends in a great measure on the roasting.

Pliny mentions it under the name of minium, but it was confused with cinnabar and the red arsenic sulphide; Dioscorides mentions its preparation from white lead or lead carbonate.

Lead carbonate, PbCO 3, occurs in nature as the mineral cerussite (q.v.).

It is produced by the addition of a solution of lead salt to an excess of ammonium carbonate, as an almost insoluble white precipitate.

Of greater practical importance is a basic carbonate, substantially 2PbCO 3 Pb(OH) 2, largely used as a white pigment under the name of "white lead."

It forms colourless transparent crystals, soluble in one and a half parts of cold water and in eight parts of alcohol, which on exposure to ordinary air become opaque through absorption of carbonic acid, which forms a crust of basic carbonate.

When carbon dioxide is passed into this solution the whole of the added oxide, and even part of the oxide of the normal salt, is precipitated as a basic carbonate chemically similar, but not quite equivalent as a pigment, to white lead.

When mixed with sodium carbonate and heated on charcoal in the reducing flame lead salts yield malleable globules of metal and a yellow oxide-ring.

The phosphatic deposit has doubtless been produced by the long-continued action of a thick bed of sea-fowl dung, which converted the carbonate of the underlying limestone into phosphate.

When cryolite is used for the preparation of alum, it is mixed with calcium carbonate and heated.

The remarkable " stone reefs " of the north-east coast are ancient beaches hardened by the infiltration of carbonate of lime.

The precipitate, after having been collected and washed, is digested with a warm concentrated solution of ammonium carbonate, which dissolves the uranium as a yellow solution of ammonium uranate, while the hydrated oxide of iron, the alumina, &c., remain.

It is manufactured by heating pitchblende with lime, treating the resulting calcium uranate with dilute sulphuric acid, and adding sodium carbonate in excess.

Its disintegration for analytical purposes can be effected by fusion with caustic alkali in silver basins, with the formation of soluble stannate, or by fusion with sulphur and sodium carbonate, with the formation of a soluble thiostannate.

Tin compounds when heated on charcoal with sodium carbonate or potassium cyanide in the reducing blowpipe flame yield the metal and a scanty ring of white Sn02.

The presence of so small a quantity as i% of alcohol may be detected in ether by the colour imparted to it by aniline violet; if water or acetic acid be present, the ether must be shaken with anhydrous potassium carbonate before the application of the test.

The action is very rapid, and the product, which rises to the top of the acids, is separated and washed successively with cold and then tepid water, and finally with water made slightly alkaline with sodium carbonate or hydroxide, to remove all adhering or dissolved acids which would otherwise render the product very unstable.

Nitroglycerin shaken up with warm very dilute alkaline solutions, as sodium carbonate, for a few minutes only, always yields sufficient nitrite to give the diazoreaction; and, as stated, strong alkaline solutions always produce some nitrite as one of the decomposition products.

The essential materials of which these mixtures are made are, for English flint glass, sand, carbonate of potash and red lead; for plate and sheet glass, sand, carbonate or sulphate of soda.

A certain proportion of soda ash (carbonate of soda) is also used in some works in sheet-glass mixtures, while " decolorizers " (substances intended to remove or reduce the colour of the glass) are also sometimes added, those most generally used being manganese dioxide and arsenic. Another essential ingredient of all glass mixtures containing sulphate of soda is some form of carbon, which is added either as coke, charcoal or anthracite coal; the carbon so introduced aids the reducing substances contained in the atmosphere of the furnace in bringing about the reduction of the sulphate of soda to a condition in which it combines more readily with the silicic acid of the sand.

For the highest quality of bottles, which are practically colourless, sand, limestone and sulphate and carbonate of soda are used.

The materials employed are sand, sulphate of soda, nitrate of soda, calcspar and in some works carbonate of barium.

The fire may well have caused the natron, an impure form of carbonate of soda, to combine with the surrounding sand to form silicate of soda, which, although not a permanent glass, is sufficiently glass-like to suggest the x11.4 FIG.

Magnesian limestone mixed and fused with sand and an alkaline carbonate produces a permanent glass.

Many are found as minerals, the more important of such naturally occurring carbonates being cerussite (lead carbonate, PbC03), malachite and azurite (both basic copper carbonates), calamine (zinc carbonate, ZnCO 3), witherite (barium carbonate, BaCO 3), strontianite (strontium carbonate, SrC03), calcite (calcium carbonate, CaC03), dolomite (calcium magnesium carbonate, CaCO 3 MgCO 3), and sodium carbonate, Na 2 CO 3.

Dumas obtained barium methyl carbonate by the action of carbon dioxide on baryta dissolved in methyl alcohol (Ann., 1840, 35, p. 283).

It is not very stable, water decomposing it into alcohol and the alkaline carbonate.

The normal esters may be prepared by the action of silver carbonate on the alkyl iodides, or by the action of alcohols on the chlorcarbonic esters.

When heated with ammonia it yields guanidine, and on boiling with alcoholic potash it yields potassium carbonate.

This is a closed vessel, into which carbonic acid gas (produced as described hereafter) is forced, and combining with the lime in the juice forms carbonate of lime.

The whole is then passed through filter presses, the clear juice being run off for further treatment, while the carbonate of lime is obtained in cakes which are taken to the fields as manure.

Chalk consists, when quite pure, of calcium carbonate (CaC03), a white solid substance useful in small amounts as a plant foodmaterial, though in excess detrimental to growth.

The material which chemists call calcium carbonate is met with in a comparatively pure state in chalk.

Carbonate of lime is also a constituent to a greater or lesser extent in almost all soils.

Pure carbonate of lime when heated loses 44% of its weight, the decrease being due to the loss of carbon dioxide gas.

This substance absorbs and combines with water very greedily, at the same time becoming very hot, and falling into a fine dry powder,' calcium hydroxide or slaked lime, which when left in the open slowly combines with the carbon dioxide of the air and becomes calcium carbonate, from which we began.

Generally speaking the oxide or quicklime has a more rapid and greater effect in modifying the soil than slaked lime, and this again greater than the carbonate or chalk.

Some of the chalk marls, which are usually of a yellowish or dirty grey colour, contain clay and 50 to 80% of carbonate of lime with a certain proportion of phosphate of lime.

The salt is obtained from the soil in which it occurs naturally, or from the heaps in which it is formed artificially, by extracting with water, and adding to the solution wood-ashes or potassium carbonate.

Second in importance is the carbonate, calamine (q.v.) or zinc spar, which at one time was the principal ore; it almost invariably contains the carbonates of cadmium, iron, manganese, magnesium and calcium, and may be contaminated with clay, oxides of iron, galena and calcite; "white calamine" owes its colour to much clay; "red calamine" to admixed iron and manganese oxides.

Oxide of zinc, like most heavy metallic oxides, is easily reduced to the metallic state by heating it to redness with charcoal; pure red zinc ore may be treated directly; and the same might be done with pure calamine of any kind, because the carbon dioxide of the zinc carbonate goes off below redness and the silica of zinc silicate only retards, but does not prevent, the reducing action of the charcoal.

Neither mechanical nor magnetic concentration can effect much in the way of separation when, as in many complex ores, carbonates of iron, calcium and magnesium replace the isomorphous zinc carbonate, when some iron sulphide containing less sulphur than pyrites replaces zinc sulphide, and when gold and silver are contained in the zinc ore itself.

This at least is true of the oxide produced from the metal by combustion; that produced from the carbonate, if once made yellow at a red heat, retains a yellow shade permanently.

The alkali must be free from carbonate and an excess of it must be avoided, otherwise the hydrate redissolves.

Both are easily removed by passing chlorine through the cold solution, to produce ferric and manganic salt, and then digesting the liquid with a washed precipitate of basic carbonate, produced from a small portion of the solution by means of sodium carbonate.

Zinc carbonate, ZnCO 3, occurs in nature as the mineral calamine (q.v.), but has never been prepared artificially, basic carbonates, ZnCO 3 .xZn(OH) 2, where x is variable, being obtained by precipitating a solution of the sulphate or chloride with sodium carbonate.

To obtain a product free of Cl or S04, there must be an excess of alkali and the zinc salt must be poured into the hot solution of the carbonate.

The basic carbonate is used as a pigment.

Zinc may be quantitatively estimated by precipitating as basic carbonate, which is dried and ignited to zinc oxide.

Those treated here are the sulphate, oxide, carbonate, oleate and acetate.

A better method is Wohler's, in which the finely powdered mineral is fused with twice its weight of potassium carbonate in a platinum crucible, the melt powdered and treated in a platinum basin with aqueous hydrofluoric acid.

If titanic oxide be fused with excess of alkaline carbonate a titanate, R 2 T103, is formed.

Titanium trioxide, T103, is obtained as a yellow precipitate by dropping the chloride into alcohol, adding hydrogen peroxide, and finally ammonium carbonate or potash.

They are obtained by neutralizing the solution of the acid, or by fusing the oxide with potassium carbonate and treating the melt with hydrofluoric acid.

Strontium fluoride, SrF 2, is obtained by the action of hydrofluoric acid on the carbonate, or by the addition of potassium fluoride to strontium chloride solution.

Strontium chloride, SrC1 2.6H 2 O, is obtained by dissolving the carbonate in hydrochloric acid, or by fusing the carbonate with calcium chloride and extracting the melt with water.

Strontium sulphide, SrS, is formed when the carbonate is heated to redness in a stream of sulphuretted hydrogen.

When boiled with alkaline carbonates it is converted into strontium carbonate.

Strontium nitrate, Sr(N03)2, is obtained by dissolving the carbonate in dilute nitric acid.

Strontium carbide, SrC2, is obtained by heating strontium carbonate with carbon in the electric furnace.

Strontium carbonate, SrCO 3, found in the mineral kingdom as strontianite, is formed when a solution of a carbonate is added to one of a strontium salt.

The causticity of alkaline bodies was explained at that time as depending on the presence in them of the principle of fire, "phlogiston"; quicklime, for instance, was chalk which had taken up phlogiston, and when mild alkalis such as sodium or potassium carbonate were causticized by its aid, the phlogiston was supposed to pass from it to them.

The oxalates are.readily decomposed onheating, leaving a residue of carbonate, or oxide of the metal.

The precipitate is collected in a filter-press, and then roasted in muffle furnaces with nitre, borax and sodium carbonate.

Its inhabitants had frequent litigations and disputes with their neighbours at Reate in connexion with the regulation of the Velinus, the waters of which are so strongly impregnated with carbonate of lime that by their deposits they tend to block up their own channel.

The former is found, generally mixed with iron, copper and arsenic oxides, in Bohemia, Siberia, Cornwall, France (Meymac) and other localities; it also occurs admixed with bismuth carbonate and hydrate.

The hydrated carbonate, bismutite, is of less importance; it occurs in Cornwall, Bolivia, Arizona and elsewhere.

Ores containing the oxide and carbonate are treated either by smelting with carbon or by a wet process.

In the wet process the ores, in which the bismuth is present as oxide or carbonate, are dissolved out with hydrochloric acid, or, if the bismuth is to be extracted from a matte or alloy, the solvent employed is aqua regia or strong sulphuric acid.

Hampe prepared chemically pure bismuth by fusing the metal with sodium carbonate and sulphur, dissolving the bismuth sulphide so formed in nitric acid, precipitating the bismuth as the basic nitrate, redissolving this salt in nitric acid, and then precipitating with ammonia.

This compound occurs in nature as bismuth ochre, and may be prepared artificially by oxidizing the metal at a red heat, or by heating the carbonate, nitrate or hydrate.

The basic carbonate, 2(B10) 2 CO 3 4H 2 O, obtained as a white precipitate when an alkaline carbonate is added to a solution of bismuth nitrate, is employed in medicine.

Another basic carbonate, 3(BiO) 2 CO 3.2Bi(OH)3.3H20, constitutes the mineral bismutite.

In quantitative estimations it is generally weighed as oxide, after precipitation as sulphide or carbonate, or in the metallic form, reduced as above.

Telluric acid, H2Te04, is obtained in the form of its salts when tellurium is fused with potassium carbonate and nitre, or by the oxidizing action of chlorine on a tellurite in alkaline solution.

But the two substances were generally confounded as "fixed alkali" (carbonate of ammonia being "volatile alkali"), till Duhamel du Monceau in 1736 established the fact that common salt and the ashes of seaplants contain the same base as is found in natural deposits of soda salts ("mineral alkali"), and that this body is different from the "vegetable alkali" obtained by incinerating land plants or wood (pot-ashes).

Pure calcareous sand and calcareous mud are formed by wave action on the shores of coral islands where the only material available is coral and the accompanying calcareous algae, crustacea, molluscs and other organisms secreting carbonate of lime.

Recent limestones are being produced in this way and also in some places by the precipitation of calcium carbonate by sodium or ammonium carbonate which has been carried into the sea or formed by organisms. The precipitated carbonate may agglomerate on mineral or organic grains which serve as nuclei, or it may form a sheet of hard deposit on the bottom as occurs in the Red Sea, off Florida, and round many coral islands in the Pacific. Only the sand and the finest-grained sediments of the shore zone are carried outwards over the continental shelf by the tides or by the reaction-currents along the bottom set up by on-shore winds.

The most abundant of the terrigenous materials are the finest particles of clay and calcium carbonate as well as fragments derived from land vegetation, of which twigs, leaves, &c., may form a perceptible proportion as far as 200 m.

The proportion of calcium carbonate varies greatly according to the amount of foraminifera and other calcareous organisms which it contains.

When the proportion of calcium carbonate in the blue mud is considerable there results a calcareous ooze, which when found on the continental slope and in enclosed seas is largely composed of remains of deep-sea corals and bottom-living foraminif era, pelagic organisms including pteropods being less frequently represented.

The bottom of the Black Sea is covered by a stiff blue mud in which Sir John Murray found much sulphide of iron,' grains or needles of pyrites making up nearly 50% of the deposit, and there are also grains of amorphous calcium carbonate evidently precipitated from the water.

It is a remarkable geographical fact that on the rises and in the basins of moderate depth of the open ocean the organic oozes preponderate, but in the abysmal depressions below 2500 or 3000 fathoms, whether these lie in the middle or near the edges of the great ocean spaces, there is found only the red clay, with a minimum of calcium carbonate, though sometimes with a considerable admixture of the siliceous remains of radiolarians.

Murray and Renard define globigerina ooze as containing at least 30% of calcium carbonate, in which the remains of pelagic (not benthonic) foraminifera predominate and in which remains of pelagic mollusca such as pteropods and heteropods, ostracodes and also coccoliths (minute calcareous algae) may also occur.

A small proportion of organic matter including the fat globules of the plankton is mixed with the calcium carbonate, the amount according to Giimbel's analysis being about 1 part in 1000.

A very interesting feature is the small proportion of calcium carbonate, the amount present being usually less as the depth is greater; red clay from depths exceeding 3000 fathoms does not contain so much as 1% of calcareous matter.

Murray and Renard recognize the progressive diminution of carbonate of lime with increase of depth as a characteristic of all eupelagic deposits.

Murray and Renard ascribe this to the greater abundance of carbonic acid in the deeper water, which aided by the increased pressure adds to the solvent power of the water for carbonate of lime.

It is, however, a curious question how, considering the increase of carbonic acid by the decomposition of organic bodies and possible submarine exhalations of volcanic origin, the water has not in some places become saturated and a precipitate of amorphous calcium carbonate formed in the deepest water.

Sorensen and Martin Knudsen after a careful investigation decided to abandon the old definition of salinity as the sum of all the dissolved solids in sea-water and to substitute for it the weight of the dissolved solids in 1000 parts by weight of sea-water on the assumption that all the bromine is replaced by its equivalent of chlorine, all the carbonate converted into oxide and the organic matter burnt.

Since 1851 it has been known that all sea-water has an alkaline reaction, and Torniie defined the alkalinity of sea-water as the amount of carbonic acid which is necessary to convert the excess of bases into normal carbonate.

The composition of the ash of true coal approximates to that of a fire-clay, allowance being made for lime, which may be present either as carbonate or sulphate, and for sulphuric acid.

Clearer evidence of their occurrence has, however, been found in fragments of wood fossilized by silica or carbonate of lime which are sometimes met with in coal seams.

Caesium sulphate, Cs 2 SO 4, may be prepared by dissolving the hydroxide or carbonate in sulphuric acid.

Caesium nitrate, CsNO 3, is obtained by dissolving the carbonate in nitric acid, and crystallizes in glittering prisms, which melt readily, and on heating evolve oxygen and leave a residue of caesium nitrite.

The loess soil, chiefly a mixture of porous clay and carbonate of lime, forms the bluffs that border the bottom lands of the Missouri.

The protoxide, OsO, is obtained as a dark grey insoluble powder when osmium sulphite is heated with sodium carbonate in a current of carbon dioxide.

The dioxide, 0s0 2, is formed when potassium osmichloride is heated with sodium carbonate in a current of carbon dioxide, or by electrolysis of a solution of the tetroxide in the presence of alkali.

For instance, if it be fused with sodium carbonate, sodium zirconate, Na2Zr03, is formed.

If the carbonate be in excess, the salt Na4Zr04 results, which when treated with water gives Na2Zr8017 12H20, which crystallizes in hexagonal plates.

Ammonia is also present, but in very varying amounts, ranging from 135 to 0 I parts (calculated as carbonate) in a million parts of air.

The soluble trimetallic salts are decomposed by carbonic acid into a dimetallic salt and an acid carbonate.

On heating with an oxide or carbonate they yield a trimetallic orthophosphate, carbon dioxide being evolved in the latter case.

In 1799 he proved that carbonate of copper, whether natural or artificial, always has the same composition, and later he showed that the two oxides of tin and the two sulphides of iron always contain the same relative weights of their components and that no intermediate indeterminate compounds exist.

Thus the sulphate constitutes the minerals anhydrite, alabaster, gypsum, and selenite; the carbonate occurs dissolved in most natural waters and as the minerals chalk, marble, calcite, aragonite; also in the double carbonates such as dolomite, bromlite, barytocalcite; the fluoride as fluorspar; the fluophosphate constitutes the mineral apatite; while all the more important mineral silicates contain a proportion of this element.

Calcium carbonate, CaCO 3, is of exceptionally wide distribution in both the mineral and animal kingdoms. It constitutes the bulk of the chalk deposits and limestone rocks; it forms over one-half of the mineral dolomite and the rock magnesium limestone; it occurs also as the dimorphous minerals aragonite (q.v.) and calcite (q.v.).

Calcium carbonate is obtained as a white precipitate, almost insoluble in water (1 part requiring Io,000 of water for soluticn), by mixing solutions of a carbonate and a calcium salt.

Calcium is not precipitated by sulphuretted hydrogen, but falls as the carbonate when an alkaline carbonate is added to a solution.

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.

Ammonia is found in small quantities as the carbonate in the atmosphere, being produced from the putrefaction of nitrogenous animal and vegetable matter; ammonium salts are also found in small quantities in rain-water, whilst ammonium chloride (sal-ammoniac) and ammonium sulphate are found in volcanic districts; and crystals of ammonium bicarbonate have been found in Patagonian guano.

Ammonium chlorate, NH 4 C10 3, is obtained by neutralizing chloric acid with either ammonia or ammonium carbonate, or by precipitating barium, strontium or calcium chlorates with ammonium carbonate.

Ammonium nitrate, NH 4 NO 3, is prepared by neutralizing nitric acid with ammonia, or ammonium carbonate, or by double decomposition between potassium nitrate and ammonium sulphate.

The solid crusts found at the bottom of the salt lakes of the Araxes plain in Armenia contain about 16% of carbonate and 80 of sulphate.

About Szegedin in Hungary and all over the vast pusztas (steppes) between the Theiss and the Danube, and from the Theiss up to and beyond Debreczin, the soil contains sodium carbonate, which frequently assumes the form of crude alkaline crusts, called "szekso," and of small saline ponds.

A purified specimen of such Debreczin soda was found to contain as much as 90% of real carbonate, NaCO 3, and 4 of common salt.

This method was followed by that proposed by Gay-Lussac and Thenard, who decomposed molten caustic soda with red-hot iron; and this in turn was succeeded by Brunner's process of igniting sodium carbonate with charcoal.

In 1886, however, Castner replaced the carbonate by caustic soda, and materially cheapened the cost of production; but this method was discarded for an electrolytic one, patented by Castner in 1890.

Acids yield a sodium salt and free oxygen or hydrogen peroxide; with carbon dioxide it gives sodium carbonate and free oxygen; carbon monoxide gives the carbonate; whilst nitrous and nitric oxides give the nitrate.

Sodium sulphite, Na2S03, which is employed as an antichlor, is prepared (with 7H20) by saturating a solution of sodium carbonate with sulphur dioxide, adding another equivalent of carbonate and crystallizing.

The acid sulphite, NaHSO 3, obtained by saturating a cold solution of the carbonate with sulphur dioxide and precipitating by alcohol, is employed for sterilizing beer casks.

The manufacture of sodium carbonate, commonly called soda, is treated under Alkali Manufacture.

The acid carbonate or bicarbonate of soda, NaHCO 3, is produced in the ammonia-soda process for alkali manufacture.

Another acid carbonate, Na2C03.2NaHC03.3H20, is the mineral trona or urao.

Poisoning by caustic soda is rare, but occasionally it takes place by swallowing soap lees (sodium carbonate), which may contain some impurities of caustic soda.

A variety of animal charcoal is sometimes prepared by calcining fresh blood with potassium carbonate in large cylinders, the mass being purified by boiling out with dilute hydrochloric acid and subsequent reheating.

The water, which is at boiling point, falls into natural basins of a creamy white colour, formed by the deposit of carbonate of lime.

These salts are sucked up by the roots of plants, and by taking part in the process of nutrition are partly converted into oxalate, tartrate, and other organic salts, which, when the plants are burned, are converted into the carbonate, K 2 CO 3.

In fact, the ashes of herbs generally are richer in potash than those of the trunks and branches of trees; yet, for obvious reasons, the latter are of greater industrial importance as sources of potassium carbonate.

Brunner's process consisted in forming an intimate mixture of potassium carbonate and carbon by igniting crude tartar in covered iron crucibles, cooling the mass, and then distilling it at a white heat from iron bottles, the vaporized metal being condensed beneath the surface of paraffin or naphtha contained in a copper vessel.

Pure potassium is a silvery white metal tinged with blue; but on exposure to air it at once forms a film of oxide, and on prolonged exposure deliquesces into a solution of hydrate and carbonate.

A solution of one part of the carbonate in 12 parts of water is heated to boiling in a cast-iron vessel (industrially by means of steampipes) and the milk of lime added in instalments until a sample of the filtered mixture no longer effervesces with an excess of acid.

The remaining mud of calcium carbonate and hydrate is washed, by decantation, with small instalments of hot water to recover at least part of the alkali diffused throughout it, but this process must not be continued too long or else some of the lime passes into solution.

All commercial caustic potash is contaminated with excess of water (over and above that in the KHO) and with potassium carbonate and chloride; sulphate, as a rule, is absent.

This product, known as "crude potashes," contains, in addition to carbonate, varying amounts of sulphate and chloride and also insoluble matter.

Crude potash is used for the manufacture of glass, and, after being causticized, for the making of soft soap. For many other purposes it must be refined, which is done by treating the crude product with the minimum of cold water required to dissolve the carbonate, removing the undissolved part (which consists chiefly of sulphate), and evaporating the clear liquor to dryness in an iron pan.

The purified carbonate (which still contains most of the chloride of the raw material and other impurities) is known as "pearl ashes."

The liquors are evaporated to dryness and the residue is ignited to obtain a very impure carbonate, which is purified by methods founded on the different solubilities of the several components.

Most of the carbonate which now occurs in commerce is made from the chloride of the Stassfurt beds by an adaptation of the "Leblanc process" for the conversion of common salt into soda ash (see Alkali Manufacture).

The latter operation furnishes an intimate mixture of the carbonate with charcoal, from which the carbonate is extracted by lixiviation with water and filtration.

The carbonate, being insoluble in strong alcohol (and many other liquid organic compounds), is much used for dehydration of the corresponding aqueous preparations.

The pure carbonate is constantly used in the laboratory as a basic substance generally, for the disintegration of silicates, and as a precipitant.

Potassium bicarbonate, Khco 3, is obtained when carbonic acid is passed through a cold solution of the ordinary carbonate as long as it is absorbed.

The solution is strongly caustic. It turns yellow on exposure to air, absorbing oxygen and carbon dioxide and forming thiosulphate and potassium carbonate and liberating sulphuretted hydrogen, which decomposes into water and sulphur, the latter combining with the monosulphide to form higher salts.

The hydrosulphide, KHS, was obtained by Gay-Lussac on heating the metal in sulphuretted hydrogen, and by Berzelius on acting with sulphuretted hydrogen on potassium carbonate at a dull red heat.

Liver of sulphur or hepar sulphuris, a medicine known to the alchemists, is a mixture of various polysulphides with the sulphate and thiosulphate, in variable proportions, obtained by gently heating the carbonate with sulphur in covered vessels.

The salt K2S03 H20 may be obtained by crystallizing the metabisulphite, K 2 S 2 0 5 (from sulphur dioxide and a hot saturated solution of the carbonate, or from sulphur dioxide and a mixture of milk of lime and potassium sulphate) with an equivalent amount of potash.

The soils of the Highland Rim Plateau as well as of the lowland west of the Tennessee river vary greatly, but the most common are a clay, containing more or less carbonate of lime, and a sandy loam.

In making the acid by this process benzaldehyde, acetic anhydride and anhydrous sodium acetate are heated for some hours to about 180 C., the resulting product is made alkaline with sodium carbonate, and any excess of benzaldehyde removed by a current of steam.

A later method consists in boiling the weed with sodium carbonate; the liquid is filtered and hydrochloric acid added to the filtrate, when alginic acid is precipitated; this is also filtered off, the filtrate neutralized by caustic soda, and the whole evaporated to dryness and carbonized, the residue obtained being known as kelp substitute.

The iodides can be prepared either by direct union of iodine with a metal, from hydriodic acid and a metal, oxide, hydroxide or carbonate, or by action of iodine on some metallic hydroxides or carbonates (such as those of potassium, sodium, barium, &c.; other products, however, are formed at the same time).

Another often successful method of preventing the onset of symptoms of poisoning is to administer small doses of ammonium carbonate with the drug, thereby neutralizing the iodic acid which is liberated in the stomach.

The older processes for the commercial preparation of this salt, which were based on the ignition of nitrogenous substances with an alkaline carbonate and carbon, have almost all been abandoned, since it is more profitable to prepare the salt from the byproducts obtained in the manufacture of illuminating gas.

The soluble salts are removed by lixiviation, and the residue is boiled with lime to form the soluble calcium ferrocyanide, which is finally converted into the potassium salt by potassium chloride or carbonate.

This mature weathering, resulting in the relatively complete separation of the quartz from the kaolin, and both from the calcium carbonate and other basic materials, implies conditions of rock decay comparable to those of the present time.

From 1889 to 1907 the average yearly percentages of the red haematite, brown ores, rnagnetite and carbonate in the total ore production were respectively 824, I0I, 7.1 and 0.4.

Chromium and its salts may be detected by the fact that they give a deep green bead when heated with borax, or that on fusion with sodium carbonate and nitre, a yellow mass of an alkaline chromate is obtained, which, on solution in water and acidification with acetic acid, gives a bright yellow precipitate on the addition of soluble lead salts.

The shell consists of an organic basis the substance of which is called conchiolin, impregnated with carbonate of lime, with a small proportion, I-2%, of phosphate of lime.

Dredging, however, is prosecuted, the sand being sent inland, being useful as a manure through the carbonate of lime with which it is impregnated.

Magnesium is found widely distributed in nature, chiefly in the forms of silicate, carbonate and chloride, and occurring in the minerals olivine, hornblende, talc, asbestos, meerschaum, augite, dolomite, magnesite, carnallite, kieserite and kainite.

It may also be prepared by heating a mixture of carbon, oxide of iron and magnesite to bright redness; and by heating a mixture of magnesium ferrocyanide and sodium carbonate, the double cyanide formed being then decomposed by heating it with metallic zinc. Electrolytic methods have entirely superseded the older methods.

Magnesium Oxide, magnesia, MgO, occurs native as the mineral periclase, and is formed when magnesium burns in air; it may also be prepared by the gentle ignition of the hydroxide or carbonate.

It may be prepared by dissolving the metal, its oxide, hydroxide, or carbonate in dilute hydrochloric acid, or by mixing concentrated solutions of magnesium sulphate and common salt, and cooling the mixture rapidly, when the less soluble sodium sulphate separates first.

It is not possible to prepare the normal carbonate by precipitating magnesium salts with sodium carbonate.

C. Marignac has prepared it by the action of calcium carbonate on magnesium chloride.

The carbonate is not easily soluble in dilute acids, but is readily soluble in water containing carbon dioxide.

Magnesia alba, a white bulky precipitate obtained by adding sodium carbonate to Epsom salts,is a mixture of Mg(CO 3 H) (OH) 2H 2 O,Mg(CO 3 H) (OH) and Mg(OH) 2.

Magnesium Nitrate, Mg(NO 3) 2.6H 2 O, is a colourless, deliquescent, crystalline solid obtained by dissolving magnesium or its carbonate in nitric acid, and concentrating the solution.

The oxide and carbonate of magnesium are also invaluable as antidotes, since they form insoluble compounds with oxalic acid and salts of mercury, arsenic, and copper.

As alkaloids are insoluble in alkaline solutions, the oxide and carbonate - especially the former - may be given in alkaloidal poisoning.

The usual doses of the oxide and carbonate of magnesium are from half a drachm to a drachm.

Many deposits of limonite have been found, on being worked, to pass downwards into ferrous carbonate; and crystals of chalybite converted superficially into limonite are well known.

To produce the alkali metal, a calcined mixture of sodium carbonate, coal and chalk was strongly ignited in flat retorts made of boiler-plate; the sodium distilled over into condensers and was preserved under heavy petroleum.

In order to prepare pure alumina, bauxite and sodium carbonate were heated in a furnace until the reaction was complete; the product was then extracted with water to dissolve the sodium aluminate, the solution treated with carbon dioxide, and the precipitate removed and dried.

Seeing that sodium was the only possible reducing agent, he set himself to cheapen its cost, and deliberately rejecting sodium carbonate for the more expensive sodium hydroxide (caustic soda), and replacing carbon by a mixture of iron and carbon - the so-called carbide of iron - he invented the highly scientific method of winning the alkali metal which has remained in existence almost to the present day.

The value of wood ashes as a manure very much depends upon the carbonate and other salts of potash which they contain.

Many fossils are mineralized with pyrites, which has evidently been reduced by the action of decomposing organic matter on a solution of ferrous sulphate, or perhaps less directly on ferrous carbonate dissolved in water containing carbonic acid, in the presence of certain sulphates.

At the same time, hot springs, containing abundant carbonate of lime in solution, produced deposits of travertine at various points.

Sodium and potassium carbonates are valuable for fluxing off silica; mixed with potassium nitrate sodium carbonate forms a valuable oxidizing fusion mixture; "black flux" is a reducing flux composed of finely divided carbon and potassium carbonate, and formed by deflagrating a mixture of argol with 4 to 2 its weight of nitre.

Now, whether a real, though undetected, change occurs is a question to be determined from case to case; it is certain, however, that a substance like aragonite (a mineral form of calcium carbonate) has sensibly persisted in geological periods, though the polymorphous calcite is the more stable form.

Lanthanum oxide, La203, is a white powder obtained by burning the metal in oxygen, or by ignition of the carbonate, nitrate or sulphate.

The mineral is fused with potassium carbonate, and, on cooling, the product is treated with sulphuric acid, the excess of which is removed by evaporation; water is then added and the silica is filtered off.

This is now treated for some days with a hot concentrated solution of ammonium carbonate, which precipitates the iron and aluminium but keeps the beryllium in solution.

To remove the iron, the precipitate is again dissolved in ammonium carbonate and steam is blown through the liquid, when beryllium oxide is precipitated.

Several basic carbonates are known, being formed by the addition of beryllium salts to solutions of the alkaline carbonates; the normal carbonate is prepared by passing a current of carbon dioxide through water containing the basic carbonate in suspension, the solution being filtered and concentrated over sulphuric acid in an atmosphere of carbon dioxide.

Beryllium salts are easily soluble and mostly have a sweetish taste (hence the name Glucinum, from yXv,dc, sweet); they are readily precipitated by alkaline sulphides with formation of the white hydroxide, and may be distinguished from salts of all other metals by the solubility of the oxide in ammonium carbonate.

It is ordinarily prepared by the fermentation of sugar or starch, brought about by the addition of putrefying cheese, calcium carbonate being added to neutralize the acids formed in the process.

This silt consists largely o alumina (about 48%) and calcium carbonate (18%) with smalle quantities of silica, oxide of iron and carbon.

The blue or green color was made by fritting together silica, lime, alkaline carbonate and copper carbonate; the latter varied from 3% in delicate blues to 20% in deep purple.blues.

Primarily but a slight deposit is formed (none until the concentration arrives at specific gravity 1.0509), this deposit consisting for the most part of calcium carbonate and ferric oxide.

Excepting where the thallus is impregnated with silica, as in Diatomaceae, or carbonate of lime, as in Corallinaceae,Characeae and some Siphonales, it is perhaps not surprising that algae should not have been extensively preserved in the fossil form.

Subsequent hardening of the mortar is caused by the gradual absorption of carbonic acid from the air by the lime, a skin of carbonate of lime being formed; but the action is superficial.

The supply of materials containing naturally suitable proportions of calcium carbonate and clay being limited, attempts were made to produce artificial mixtures which would serve a similar end.

True, it is possible to manufacture Portland cement from Portland stone (after adding a suitable quantity of clay), but this is merely because Portland stone is substantially carbonate of lime; any other limestone would serve equally well.

Thus when hard limestone is the form of calcium carbonate locally available, it is ground dry and mixed with the correct proportion of clay also dried and ground.

As it descends it reaches a part of the kiln where the temperature is higher; here the carbonic acid of the carbonate of lime, and the combined water of the clay are driven off, and the resulting lime begins to act chemically on the dehydrated clay.

This limestone consists of calcium carbonate most intimately intermixed with very finely divided silica.

The term Natural Cements is applied to cements made by burning mixtures of clay and carbonate of lime naturally occurring in approximately suitable proportions.

In this case the action of the water is checked by the film of carbonate of lime which eventually forms on the surface of calcareous cement.

Carbonate of soda solution dissolves it pretty freely.

Thallous fluoride, T1F, forms white glistening octahedra; it is obtained by crystallizing a solution of the carbonate in hydrofluoric acid.

Thallous carbonate, T1 2 CO 31 more nearly resembles the lithium compound than any other ordinary carbonate.

Thallous nitrate, T1NO 31 is obtained as white, rhombic prisms by crystallizing a solution of the metal, oxide, carbonate, &c., in nitric acid.

Thallic hydroxide, TI(OH) 31 is obtained as a brown precipitate by adding a hot solution of thallous chloride in sodium carbonate to a solution of sodium hypochlorite.

The precipitate is dissolved in boiling water, decolorized by potassium permanganate and decomposed by barium carbonate.

Liebig (Ann., 18 53, 8 5, p. 289) precipitates dilute solutions of urea with a dilute standard solution of mercuric nitrate, using alkaline carbonate as indicator.

Benzamide, C 6 H 5 CONH 2, is prepared by the action of benzoyl chloride on ammonia or ammonium carbonate, or from ethyl benzoate and ammonia.

Such mixtures are obtained by the action of alkaline hypochlorites on manganous salts, or by suspending manganous carbonate in water and passing chlorine through the mixture.

The anhydrous chloride, MnCl2, is obtained as a rose-red crystalline solid by passing hydrochloric acid gas over manganese carbonate, first in the cold and afterwards at a moderate red heat.

The hydrated chloride, MnCl2.4H2O, is obtained in rose-red crystals by dissolving the metal or its carbonate in aqueous hydrochloric acid and concentrating the solution.

Manganous Sulphide, MnS, found native as manganese glance, may be obtained by heating the monoxide or carbonate in a porcelain tube in a current of carbon bisulphide vapour.

Manganese salts can be detected by the amethyst colour they impart to a borax-bead when heated in the Bunsen flame, and by the green mass formed when they are fused with a mixture of sodium carbonate and potassium nitrate.

Manganese may be estimated quantitatively by precipitation as carbonate, this salt being then converted into the oxide, Mn 3 0 4 by ignition; or by precipitation as hydrated dioxide by means of ammonia and bromine water, followed by ignition to NIn 3 0 4.

The sesquioxide, Ce 2 O 3, is obtained by heating the carbonate in a current of hydrogen.

Cerium dioxide, Ce02, is produced when cerium carbonate, nitrate, sulphate or oxalate is heated in air.

The word " alkali " denotes both soda and potash, but by "alkali manufacture" we understand merely the manufacture of sodium sulphate, carbonate and hydrate.

The term alkali is employed in a technical sense for the carbonate and hydrate (of sodium), but since in the Leblanc process the manufacture of sodium sulphate necessarily precedes that of the carbonate, we include this as well as the manufacture of hydrochloric acid which is inseparable from it.

The sodium sulphate is afterwards fluxed with calcium carbonate and coal, and a mixture is thus obtained from which sodium carbonate can be extracted by exhausting it with water.

This liquor is first treated with carbonate of lime (ground chalk or limestone) in a " neutralizing-well," made of acid-proof material and provided with wooden stirring-gear.

Similar liquids are obtained with a basis of sodium (" eau de Javel "), by passing chlorine into solutions of sodium carbonate.

A number of secondary reactions, however, occur, owing partly to the excess of calcium carbonate and coal and partly to the impurities present, so that the solid product of the process, which is called " black-ash," has a somewhat complicated composition.

Its principal constituents are always sodium carbonate and calcium sulphide, which are separated by the action of water, the former being soluble and the latter insoluble.

The lixiviation of the blackash requires great care, as the calcium sulphide is liable to be changed into soluble calcium compounds, which immediately react with sodium carbonate and destroy a corresponding quantity of the latter, rendering the soda weaker and impure.

This change of the calcium sulphide may be brought about either by the oxidizing action of the air or by " hydrolysis," produced by prolonged contact with hot water, the use of which, on the other hand, cannot be avoided in order to extract the sodium carbonate itself.

The clear vat-liquor, if allowed to cool down to ordinary temperature, would separate out part of the sodium carbonate in the shape of decahydrated crystals.

It is continued until the contents of the pan have been coverted into a thick paste of small crystals of monohydrated sodium carbonate, permeated by a mother-liquor which is removed by draining on perforated plates or by a centrifugal machine, and is always returned to the pans.

It is not easy to make it stronger than 92% of sodium carbonate, which is technically expressed as " 52 degrees of available soda " (see next page).

If purer and stronger soda-ash is wanted, the boiling down must be carried out in pans fired from below, and the crystals of monohydrated sodium carbonate " fished " out as they are formed, but this is mostly done after submitting the liquor to the purifying operations which we shall now describe.

The operation is finished when all the sodium sulphide has been converted into normal sodium carbonate, partly also into acid sodium carbonate (bicarbonate) NaHCO 3; at the same time a precipitate is formed, consisting of ferrous sulphide, alumina and silica, which is removed by another settling tank, and the clear liquor is now ready either for boiling down in a " fishing-pan " for the manufacture of white soda-ash, or for the process of causticizing.

The calcium carbonate, being insoluble, is easily separated from the caustic liquor by filtration.

At the best about 92% of the sodium carbonate can be converted into caustic soda, 8% remaining unchanged.

After from half an hour to a whole hour the conversion of sodium carbonate into sodium hydrate is brought about as far as is practicable.

The washed-out calcium carbonate, which always contains much calcium hydrate and 2 or 3% of soda in various forms, usually goes back to the black-ash furnaces, but it cannot be always used up in this way, and what remains is thrown upon a heap outside the works.

The clear caustic soda liquor must be concentrated in such a way that the caustic soda cannot to any great extent be reconverted into sodium carbonate, and that the " salts " which it contains, sodium carbonate, sulphate, chloride, &c., can be separated during the process.

Their formula in Na 2 CO 3, 10H 2 O, corresponding to 37% of dry sodium carbonate.

The wet alkali-waste as it comes from the lixiviating vats, is transferred into upright iron cylinders in which it is systematically treated with lime-kiln gases until the whole of the calcium sulphide has been converted into calcium carbonate, the carbon dioxide of the lime-kiln gases being entirely exhausted.

The steam causes the action of the lime on the ammonium chloride to take place in this lower portion of the still, from which the steam, mixed with all the liberated ammonia, rises into the upper portion of the column where its heat serves to drive out the volatile ammonium carbonate.

The solution is poured into water and sodium carbonate is added to neutralize the excess of acid, when the sodium salt of the monosulphonic acid (known as silver salt) separates out.

This is converted into the sodium salt by means of sodium carbonate, and on alkali fusion yields flavopurpurin.

Kankar or ghutin (concretionary carbonate of lime) is collected for this purpose from the river-beds and alluvial deposits.

It sometimes contains as much as 7 0% of carbonate of lime; but generally the amount is much less and the fluxing value proportionally diminished.

The metal is obtained from zinc blende (which only contains it in very small quantity) by dissolving the mineral in an acid, and precipitating the gallium by metallic zinc. The precipitate is dissolved in hydrochloric acid and foreign metals are removed by sulphuretted hydrogen; the residual liquid being then fractionally precipitated by sodium carbonate, which throws out the gallium before the zinc. This precipitate is converted into gallium sulphate and finally into a pure specimen of the oxide, from which the metal is obtained by the electrolysis of an alkaline solution.

The gallium salts are precipitated by alkaline carbonates and by barium carbonate, but not by sulphuretted hydrogen unless in acetic acid solution.

The monoxide, NiO, occurs naturally as bunsenite, and is obtained artificially when nickel hydroxide, carbonate, nitrate or sulphate is heated.

Rubidium nitrate, RbNO 3, obtained by the action of nitric acid on the carbonate, crystallizes in needles or prisms and when strongly heated is transformed into a mixture of nitrite and oxide.

Rubidium carbonate, Rb2C03, formed by the addition of ammonium carbonate to rubidium hydroxide, is a crystalline mass which melts in its water of crystallization when heated.

Tungsten may be prepared from wolfram by heating the powdered ore with sodium carbonate, extracting the sodium carbonate with water, filtering and adding an acid to precipitate tungstic acid, H 2 W0 4.

A crystalline form was obtained by Debray as olive-green prisms by igniting a mixture of sodium tungstate and carbonate in a current of hydrochloric acid gas, and by Nordenskjold by heating hydrated tungstic acid with borax.

This salt is obtained by roasting wolfram with sodium carbonate, lixiviating, neutralizing the boiling filtrate with hydrochloric acid and crystallizing at ordinary temperatures.

A blue bronze, Na2W5015, forming dark blue cubes with a red reflex, is obtained by electrolysing fused sodium paratungstate; a purple-red variety, Na2W309, and a reddish yellow form result when sodium carbonate and sodium tungstate are heated respectively with tungsten trioxide and tinfoil.

It is sparingly soluble in cold water, but is easily dissolved by potassium carbonate or ammonia.

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.

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.

The water is bitter and undrinkable, being largely impregnated with carbonate and sulphate of soda with some borax.

The water in them is exquisitely pure, except as it is impregnated by the carbonate of lime, which often forms concretions, called according to their size, pearls, eggs and snowballs.

In some of the smaller basins it sometimes happens that, when the excess of carbonate acid escapes rapidly, there is formed, besides the crystal bed below, a film above, shot like a sheet of ice across the surface.

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.

Claussen's process consisted in steeping flax fibre or tow for twenty-four hours in a weak solution of caustic soda, next boiling it for about two hours in a similar solution, and then saturating it in a solution containing 5% of carbonate of soda, after which it was immersed in a vat containing water acidulated with z% of sulphuric acid.

The action of the acid on the carbonate of soda with which the fibre was impregnated caused the fibre to split up into a fine cotton-like mass, which it was intended to manufacture in the same manner as cotton.

Copper is not affected by exposure in dry air, but in a moist atmosphere, containing carbonic acid, it becomes coated with a green basic carbonate.

Frequently intermixed with the green malachite is the blue carbonate chessylite or azurite, an ore containing when pure 55.16% of the metal.

The ores of any economic importance contain the copper either as oxide, carbonate, sulphate or sulphide.

Ores in which the copper is present as oxide or carbonate are soluble in sulphuric or hydrochloric acids, ferrous chloride, ferric sulphate, ammoniacal compounds and sodium thiosulphate.

The solubility of copper carbonate in ferrous chloride solution was pointed out by Max Schaffner in 1862, and the subsequent recognition of the solubility of the oxide in the same solvent by James Douglas and Sterry Hunt resulted in the " Douglas-Hunt " process for the wet extraction of copper.

Ferrous chloride decomposes the copper oxide and carbonate with the formation of cuprous and cupric chlorides (which remain in solution), and the precipitation of ferrous oxide, carbon dioxide being simultaneously liberated from the carbonate.

Cupric oxide, CuO, occurs in nature as the mineral melaconite (q.v.), and can be obtained as a hygroscopic black powder by the gentle ignition of copper nitrate, carbonate or hydroxide; also by heating the hydroxide.

Normal cupric carbonate, CuCO 3, has not been definitely obtained, basic hydrated forms being formed when an alkaline carbonate is added to a cupric salt.

Copper carbonate is also the basis of the valuable blue to green pigments verditer, Bremen blue and Bremen green.

Mountain or mineral green is a naturally occurring carbonate.

In the vicinity there are the most important deposits of zinc and lead in the state, and the city derives its name from the deposits of sulphide of lead (galena), which were the first worked about here; below the galena is a zone of zinc carbonate (or smithsonite) ores, which was the main zone worked between 1860 and 1890; still lower is a zone of blende, or zinc sulphide, now the principal source of the mineral wealth of the region.

It can also be obtained by the ignition of an intimate mixture of the carbonate and carbon, and in small quantities by the ignition of the iodate.

This sulphide is then heated in a current of moist carbon dioxide, barium carbonate being formed, BaS+H 2 O+CO 2 =BaCO 3 +H 2 S, and finally the carbonate is decomposed by a current of superheated steam, BaC03+H20 = Ba(OH) 2 + C02, leavingaresidue of the hydroxide.

Barium bromide is prepared by saturating baryta-water or by decomposing barium carbonate with hydrobromic acid.

It can also be obtained by suspending barium carbonate in boiling water and passing in chlorine.

Barium nitrate, Ba(N03)2, is prepared by dissolving either the carbonate or sulphide in dilute nitric acid, or by mixing hot saturated solutions of barium chloride and sodium nitrate.

Barium carbonate, BaCO 31 occurs rather widely distributed as witherite, and may be prepared by the addition of barium chloride to a hot solution of ammonium carbonate, when it is precipitated as a dense white powder of specific gravity 4.3; almost insoluble in water.

The supply of borax is, however, mainly derived from the boric acid of Tuscany, which is fused in a reverberatory furnace with half its weight of sodium carbonate, and the mass after cooling is extracted with warm water.

An alternative method is to dissolve sodium carbonate in lead-lined steamheated pans, and add the boric acid gradually; the solution then being concentrated until the borax crystallizes.