Lime Sentence Examples
Salt, lime and gypsum are abundant.
Opposite the castle is the Dropping Well, the waters of which are impregnated with lime and have petrifying power, this action causing the curious and beautiful incrustations formed where the water falls over a slight cliff.
The land around Beauly is fertile and the town drives a brisk trade in coal, timber, lime, grain and fish.
The ground is to be pared and burnt, and unslacked lime must be added to the ashes.
Next rolls Thomaston lime, a prime lot, which will get far among the hills before it gets slacked.Advertisement
Limestone is quarried at Buxton, Millersdale and Matlock for lime, fluxing and chemical purposes.
Of lime, very little is taken up by the cereal crops, and by the root-crops much less than of potash; more by the leguminous than by the other crops, and, by the clover especially, sometimes much more than by all the other crops of the rotation put together.
The chief mineral product is the asphalt of the mines of Seyssel on the eastern frontier, besides which potter's clay, building stone, hydraulic lime and cement are produced in the department.
It was about this time that the value of a mixture of lime and sulphate of copper (bouillie bordelaise), sprayed in solution upon the growing plants, came to be recognized as a check upon the ravages of potato disease.
Very little of the lime of the crops, however, goes off in the saleable products of the farm in the case of the self-supporting rotation under consideration.Advertisement
But when Venice took possession of the mainland her builders were able to employ a strong hydraulic dark lime from Albettone, which formed a durable cement, capable of resisting salt water and the corrosive sea air.
The mineral wealth of Ohio consists largely of bituminous coal and petroleum, but the state also ranks high in the production of natural gas, sandstone, limestone, grindstone, lime and gypsum.
In the township are several villages, including Salisbury, Lakeville, Lime Rock, Chapinville and Ore Hill.
Among the manufactures are charcoal, pig-iron, car wheels and general castings at Lime Rock, cutlery at Lakeville, and knife-handles and rubber brushes at Salisbury.
It is remarkable that even a small addition of zinc-white (oxide of zinc) to the reddish varieties especially causes a considerable diminution in the intensity of the colour, while dilution with artificial precipitated sulphate of lime ("annalin") or sulphate of baryta ("blanc fix") acts pretty much as one would expect.Advertisement
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.
We can prepare, in the laboratory, a white powder that proves to be calcium carbonate, that is, it appears to be wholly composed of carbon dioxide and lime.
We find in nature two other unlike substances, marble and Iceland spar, each of which is wholly composed of carbon dioxide and lime.
This salt may be prepared by digesting flowers of sulphur with sodium sulphite solution or by boiling sulphur with milk of lime.
Throughout the southern portion sand is a large ingredient, and to the northward there is more or less lime.Advertisement
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.
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.
Although the state has a great amount of limestone, especially in Erie and Ottawa counties, its dull colour renders it unsuitable for most building purposes.` It is, however, much used as a flux for melting iron and for making quick lime.
Ironstone, peat and lime are found in the vicinity.
It is made on a large scale from lime or lemon juice, and also by the fermentation of glucose under the influence of Citromycetes pfefferianus, C. glaber and other ferments.Advertisement
Calcium citrate must be manufactured with care to avoid an excess of chalk or lime, which would precipitate constituents of the juice that cause the fermentation of the citrate and the production of calcium acetate and butyrate.
At the inception of the industry kerosene came into the market as a dark yellow or reddish-coloured liquid, and in the first instance, the removal of colour was attempted by treatment with soda lye and lime solution.
In a scientific definition the compounds of fatty acids with basic metallic oxides, lime, magnesia, lead oxide, &c., should also be included under soap; but, as these compounds are insoluble in water, while the very essence of a soap in its industrial relations is solubility, it is better to speak of the insoluble compounds as " plasters, " limiting the name " soap " as the compounds of fatty acids with soda and potash.
It may be more conveniently prepared by passing the vapour of sulphur over red hot charcoal, the unccndensed gases so produced being led into a tower containing plates over which a vegetable oil is allowed to flow in order to absorb any carbon bisulphide vapour, and then into a second tower containing lime, which absorbs any sulphuretted hydrogen.
The crude product is very impure and possesses an offensive smell; it may be purified by forcing a fine spray of lime water through the liquid until the escaping water is quite clear, the washed bisulphide being then mixed with a little colourless oil and distilled at a low temperature.
The granite (biotite, biotite-muscovite and quartz-monzonite) is of fine quality, and has been used extensively in the United States for building and monumental purposes; and the burning of lime is by far the most important industry of the city.
Rockland was settled in 1769, but its growth began only with the establishment of the lime industry in 1795.
Balard discovered chlorine monoxide in 1834, investigating its properties and reactions; and his observations on hypochlorous acid and hypochlorites led him to conclude that " bleaching-powder " or " chloride of lime " was a compound or mixture in equimolecular proportions of calcium chloride and hypochlorite, with a little calcium hydrate.
The halogens may be sometimes detected by fusing with lime, and testing the solution for a bromide, chloride and iodide in the usual way.
Salt and phosphates of lime are exported.
It was valued chiefly on account of its brilliancy of tone and its inertness in opposition to sunlight, oil, and slaked lime (in fresco-painting).
Artificial, like natural, ultramarine has a magnificent blue colour, which is not affected by light nor by contact with oil or lime as used in painting.
The department produces lime, grindstones and brick-clay.
The foundation of the island is in many places almost pure carbonate of lime, and there are numerous small limekilns.
It was found advantageous not to work for acid but for a basic calcium nitrate (normal calcium nitrate being very deliquescent); for this purpose the acid is treated with the requisite amount of milk of lime.
In 1862 Fleck passed a mixture of steam, nitrogen and carbon monoxide over red-hot lime, whilst in 1904 Woltereck induced combination by passing steam and air over red-hot iron oxide (peat is used in practice).
The mineral wealth of the department is considerable, including coal as well as manganese and bituminous schist; plaster, building stone and hydraulic lime are also produced.
Lime is transported in solution as sulphate and bicarbonate, both of which salts are soluble to some extent in water.
Lime is, in fact, absorbed to an enormous extent by fishes, molluscs, crustacea, calcareous algae and sponges, starfishes, sea-urchins and feather stars, many polyzoa and a multitude of protozoa (mainly the foraminifera).
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.
It is then coagulated by the addition of an acid liquid, acetic acid or lime juice being generally employed, and the mixture allowed to stand.
In commercial importance Iloilo ranks next to Manila among Philippine cities; it has manufactures of pina, jusi, coconut oil, lime, vinegar and various articles made from palm wood.
The oak, elm, hazel, ash, apple, lime and maple disappear to the east of the Urals, but reappear in new varieties on the eastern slope of the border-ridge of the great plateau.
In Lingula the shell is composed of alternate layers of chitin and of phosphate of lime.
It is decomposed, on dry distillation, into carbon dioxide and pyromellitic acid, C i oH 6 0 8 i when distilled with lime it gives carbon dioxide and benzene.
The slag is a waste product, and the flue-dust, collected by special devices in dust-chambers, is briquetted by machinery, with lime as a bond, and then resmelted with the ore-charge.
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.
The residue is then dissolved in hot water, filtered, and the clear solution is mixed with very thin milk of lime so adjusted that it takes out one-half of the chlorine of the PbC1 2.
On these rounded hills occurs the deposit of phosphate of lime which gives the island its commercial value.
Among the rocks then obtained and submitted to Sir John Murray for examination there were detected specimens of nearly pure phosphate of lime, a discovery which eventually led, in June 1888, to the annexation of the island to the British crown.
Cattle, phosphate of lime and salt, manufactured from a lake in the interior, are the principal exports, the market for these being the neighbouring island of St Thomas.
The remarkable " stone reefs " of the north-east coast are ancient beaches hardened by the infiltration of carbonate of lime.
Small up to the beginning of the 19th century, Holywell has increasingly prospered, thanks to lime quarries, lead, copper and zinc mines, smelting works, a shot manufactory, copper, brass, iron and zinc works; brewing, tanning and mineral water, flannel and cement works.
It is manufactured by heating pitchblende with lime, treating the resulting calcium uranate with dilute sulphuric acid, and adding sodium carbonate in excess.
The department imports coal, lime, stone, salt, raw sulphur, skins and timber and exports agricultural and mineral products, bricks and tiles, and other manufactured goods.
As pure tin does not tarnish in the air and is proof against acid liquids, such as vinegar, lime juice, &c., it is utilized for culinary and domestic vessels.
Hannibal is the trade centre of a rich agricultural region, and has an important lumber trade, railway shops, and manufactories of lumber, shoes, stoves, flour, cigars, lime, Portland cement and pearl buttons (made from mussel shells); the value of the city's factory products increased from $2,698,720 in 1900 to $4,442,099 in 1905, or 64.6%.
His nose is not only the flattest, but also the smallest among the IndoChinese; his eyes are rarely oblique; his mouth is large and his lips thick; his teeth are blackened and his gums destroyed by the constant use of the betel-nut, the areca-nut and lime.
The city's chief interest is in the tobacco industry; it has also considerable trade in other agricultural products and in coal; and its manufactures include carriages and wagons, bricks, lime, flour and dressed lumber.
The distillate is purified by treatment with lime and calcium chloride, and subsequent distillation.
Clay-pipes may also give rise to cancer of lips in males in England, while cancer of the mouth of both sexes is common in India where chewing a mixture of betel leaves, areca-nut, tobacco and slaked lime is the usual practice.
The old idea of the circulating blood being supersaturated with lime salts which in some way had first become liberated from atrophying bones, and then deposited, to form calcified areas in different tissues will have to be given up, as there is no evidence that this " metastatic " calcification ever takes place.
In all probability no excess of soluble lime salts in the blood or lymph can ever be deposited in healthy living tissues.
When mine water is acid the working parts of the pump must be lined with or made of bronze or other non-corrosive material; or the acid may be neutralized by adding lime in the sump.
It appears that with soils which are not rich in humus or not deficient in lime, calcium cyanamide is almost as good, nitrogen for nitrogen, as ammonium sulphate or sodium nitrate; but it is of doubtful value with peaty soils or soils containing little lime, nor is it usefully available as a top-dressing or for storing.
The great bulk of the silver work is in the form of bowls of different sizes, in shape something like the lower half of a barrel, only more convex, of betel boxes, cups and small boxes for lime.
Semi-opacity and opacity are usually produced by the addition to the glass-mixtures of materials which will remain in suspension in the glass, such as oxide of tin, oxide of arsenic, phosphate of lime, cryolite or a mixture of felspar and fluorspar.
The older optical glasses, now generally known as the " ordinary " crown and flint glasses, are all of the nature of pure silicates, the basic constituents being, in the case of crown glasses, lime and soda or lime and potash, or a mixture of both, and in the case of flint glasses, lead and either (or both) soda and potash.
A more important outcome, however, of Italian influence was the production, in emulation of Venetian glass, of a glass made of refined potash, lime and sand, which was more colourless than the material it was intended to imitate.
The invention, if it may be regarded as one, consisted in eliminating lime from the glass mixture, substituting refined potash for soda, and using a very large proportion of lead oxide.
Mitscherlich prepared it in 1834 by distilling benzoic acid with lime; and in 1845 Hofmann discovered it in coal-tar.
It is well after the borders are completed to remove the top soil, in which no roots are to be found, every two or three years, and to replace it with a mixture of good loam, rotten manure, lime rubbish and bone meal, to the depth of 6 or 7 in.
This disease has been successfully treated with a spray of copper sulphate and lime, or sulphate of iron; solutions of these salts prevent the conidia from germinating.
They are neutral to litmus and do not combine with dilute acids or bases; strong bases, such as lime and baryta, yield saccharates, whilst, under certain conditions, acids and acid anhydrides may yield esters.
In 1861 Butlerow obtained a sugar-like substance, methylenitan, by digesting trioxymethylene, the solid polymer of formaldehyde, with lime.
Loew, who prepared in 1885 a sweet, unfermentable syrup, which he named formose, C6H120e and, later, by using magnesia instead of lime, he obtained the fermentable methose.
Like glucose it gives saccharates with lime, baryta and strontia.
As cold juice has a greater affinity for lime than hot juice, it is best to treat the juice with lime when cold.
To make this apparatus more perfectly automatic, an arrangement for continually adding to and mixing with the juice the proper proportion of milk of lime has been adapted to it; and although it may be objected that once the proportion has been determined no allowance is made for the variation in the quality of the juice coming from the mill owing to the variations that may occur in the canes fed into the mills, it is obviously as easy to vary the proportion with the automatic arrangement from time to time as it is to vary in each separate direction, if the man in charge will take the trouble to do so, which he very seldom does with the ordinary defecators, satisfying himself with testing the juice once or twice in a watch.
In diffusion plants the milk of lime is added, in proper proportion, in the cells of the diffusion battery, and the chips or slices themselves act as a mechanical filter for the juice; while in the Sandwich Islands coral-sand filters have been employed for some years, in addition to the chips, to free the juice from impurities held in mechanical suspension.
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.
The juice, which has now become comparatively clear, is again treated with lime, and again passed through a saturator and filter presses, and comes out still clearer than before.
It is then treated with sulphurous acid gas, for the purpose of decolorization, again limed to neutralize the acid, and then passed through a third saturator wherein all traces of lime and sulphur are removed.
A process for purifying and decolorizing the juice expressed from beetroots by the addition of a small quantity of manganate of lime (20 to 50 grammes per hectolitre of juice), under the influence of an electric current, was worked with considerable success in a sugar factory in the department of Seine-et-Marne in the year 1900-1901.
A saving of 40% is stated to be effected in lime.
If by this process a more perfect defecation and purification of the juice is obtained, it will no doubt be highly beneficial to the cane p lanter, though no great economy in lime can be effected, because but very little is used in a cane factory in comparison with the amount used in a beet factory.
The carbonic acid gas injected into the highly limed juice in the saturators is made by the calcination of limestone in a kiln provided with three cleaning doors, so arranged as to allow the lime to be removed simultaneously from them every six hours.
The syrup in the cistern is allowed to remain for about twelve hours, by which time the char will have absorbed all the colouring matter in it, as well as the lime.
After the sweets have come away, cold water is passed through the char until no trace of lime or sulphate of lime is found in it; then a large manhole at the bottom of the cistern is opened, and the washed and spent char is removed.
Lime of exceptionally good quality is burnt to a large extent in the neighbourhood, and forms an important article of trade; it is derived from the Lower Chalk formation.
The soils overlying red sandstone rocks would be reddish and of a sandy nature, while those overlying chalk would be whitish and contain considerable amounts of lime.
It has long been known that when organic materials such as the dung and urine of animals, or even the bodies of animals and plants, are applied to the soil, the nitrogen within them becomes oxidized, and ultimately appears in the form of nitrate of lime, potash or some other base.
It is the business of the farmer and gardener to promote the activity of these organisms by good tillage, careful drainage and occasional application of lime to soils which are deficient in this substance.
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.
The resulting white product is termed calcium oxide lime, burnt lime, quicklime, cob lime, or caustic lime.
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.
When recommendations are made about liming land it is necessary to indicate more precisely than is usually done which of the three classes of material named above - chalk, quicklime or slaked lime - is intended.
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.
Lime in whatever form it is applied has a many-sided influence in the fertility of the land.
The addition of small quantities of lime, especially in a caustic form, to stiff greasy clays makes them much more porous and pliable.
A lump of clay, which if dried would become hard and intractable, crumbles into pieces when dried after adding to it 2% of lime.
The lime causes the minute separate particles of clay to flocculate or group themselves together into larger compound grains between which air and water can percolate more freely.
It is this power of creating a more crumbly tilth on stiff clays that makes lime so valuable to the farmer.
Lime also assists in the decomposition of the organic matter or humus in the soil and promotes nitrification; hence it is of great value after green manuring or where the land contains much humus from the addition of bulky manures such as farm-yard dung.
This tendency to destroy organic matter makes the repeated application of lime a pernicious practice, especially on land which contains little humus to begin with.
Although good crops may follow the application of lime, the latter is not a direct fertilizer or manure and is no substitute for such.
Lime is a base and neutralizes the acid materials present in badly drained meadows and boggy pastures.
Land which contains less than about z /c, of lime usually needs the addition of this material.
The particular form in which lime should be applied for the best results depends upon the nature of the soil.
In practice the proximity to chalk pits or lime kilns, the cost of the lime and cartage, will determine which is most economical.
It contains a certain amount of unaltered caustic lime and slacked lime, along with sulphates and sulphides of lime, some of which have an evil odour.
S i milarly soils can be improved by applying to them marl, a substance consisting of a mixture of clay with variable proportions of lime.
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.
Such a material would not only have an influence on the texture of the land but the lime would reduce the sourness of the land and the phosphate of lime supply one of the most valuable of plant foodconstituents.
Typical clay-marls are tenacious, soapy clays of yellowish-red or brownish colour and generally contain less than 50% of lime.
Even stiff soils deficient in lime are greatly improved in fertility by the addition of marls.
The demand for saltpetre as an ingredient of gunpowder led to the formation of saltpetre plantations or nitriaries, which at one time were common in France, Germany, and other countries; the natural conditions were simulated by exposing heaps of decaying organic matter mixed with alkalies (lime, &c.) to atmospheric action.
Wall-saltpetre or lime saltpetre, calcium nitrate, Ca(N03)2, is found as an efflorescence on the walls of stables; it is now manufactured in large quantities by fixing atmospheric nitrogen, i.e.
Rejecting the old notion that plants derive their nourishment from humus, he taught that they get carbon and nitrogen from the carbon dioxide and ammonia present in the atmosphere, these compounds being returned by them to the atmosphere by the processes of putrefaction and fermentation - which latter he regarded as essentially chemical in nature - while their potash, soda, lime, sulphur, phosphorus, &c., come from the soil.
It may be prepared by the fusion of para-toluene sulphonic acid with potash; by the action of nitrous acid on para-toluidine; or by heating para-oxyphenyl acetic acid with lime.
The furnace used by Henri Moissan in his experiments on reactions at high temperatures, on the fusion and volatilization of refractory materials, and on the formation of carbides, suicides and borides of various metals, consisted, in its simplest form, of two superposed blocks of lime or of limestone with a central cavity cut in the lower block, and with a corresponding but much shallower inverted cavity in the upper block, which thus formed the lid of the furnace.
Alumina and lime, for example, which cannot be reduced at ordinary furnace temperatures, readily give up their oxygen to carbon in the electric furnace, and then combine with an excess of carbon to form metallic carbides.
When prolonged heating is required at very high temperatures it is found necessary to line the furnace-cavity with alternate layers of magnesia and carbon, taking care that the lamina next to the lime is of magnesia; if this were not done the lime in contact with the carbon crucible would form calcium carbide and would slag down, but magnesia does not yield a carbide in this way.
In starting the furnace, the bottom is prepared by ramming it with charcoal-powder that has been soaked in milk of lime and dried, so that each particle is coated with a film of lime, which serves to reduce the loss of current by conduction through the lining when the furnace becomes hot.
Tafel, Ber., 1886, 19, p. 1924), by distilling the amido-acids with lime, by heating phenols with zinc chloride ammonia (V.
The common manner of using it is to masticate the dried leaves with a little lime.
The Alexandrians prepared oil of turpentine by distilling pine-resin; Zosimus of Panopolis, a voluminous writer of the 5th century A.D., speaks of the distillation of a "divine water" or "panacea" (probably from the complex mixture of calcium polysulphides, thiosulphate, &c., and free sulphur, which is obtained by boiling sulphur with lime and water) and advises "the efficient luting of the apparatus, for otherwise the valuable properties would be lost."
Prior to 1830, little was known of the process other than that organic compounds generally yielded tarry and solid matters, but the discoveries of Liebig and Dumas (of acetone from acetates), of Mitscherlich (of benzene from benzoates) and of Persoz (of methane from acetates and lime) brought the operation into common laboratory practice.
It is a white amorphous powder which resembles lime in its general character.
The value of the clay products, lime and talc, decreased from $245,378 in 1907 to $112,815 in 1908.
In this process cellulose (in the form of sawdust) is made into a stiff paste with a mixture of strong caustic potash and soda solution and heated in flat iron pans to 20o-250 C. The somewhat dark-coloured mass is lixiviated with a small amount of warm water in order to remove excess of alkali, the residual alkaline oxalates converted into insoluble calcium oxalate by boiling with milk of lime, the lime salt separated, and decomposed by means of sulphuric acid.
The antidotes for oxalic acid poisoning are milk of lime, chalk, whiting, or even wall-plaster, followed by evacuation brought about by an enema or castor oil.
No trace of the marble seats mentioned by Pausanias has been found, but they have probably been carried off for lime or building, as they could easily be removed.
This water cannot be entirely removed by fractional distillation, and to prepare anhydrous or "absolute" alcohol the commercial product must be allowed to stand over some dehydrating agent, such as caustic lime, baryta, anhydrous copper sulphate, &c., and then distilled.
Salt is added in the roasting to convert any lime, magnesia or lead which may be present, into the corresponding chlorides.
Chlorine is generated within the barrel from sulphuric acid and chloride of lime.
This dissolves out the zinc. Lime is added to bring down the gold, and the sediment, after washing and drying, is fused in graphite crucibles.
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.
Calcination in reverberatory furnaces and a subsequent smelting in the same type of furnace with the addition of about 3% of coal, lime, soda and fluorspar, has been adopted for treating the Bolivian ores, which generally contain the sulphides of bismuth, copper, iron, antimony, lead and a little silver.
The method of making these "mild" alkalis into "caustic" alkalis by treatment with lime was practised in the time of Pliny in connexion with the manufacture of soap, and it was also known that the ashes of shore-plants yielded a hard soap and those of land-plants a soft one.
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.
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.
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.
Wohler first made calcium carbide, and found that water decomposed it into lime and acetylene.
Moissan in France that if lime and carbon be fused together at the temperature of the electric furnace, the lime is reduced to calcium, which unites with the excess of carbon present to form calcium carbide.
In the manufacture of calcium carbide in the electric furnace, lime and anthracite of the Manufac- highest possible degree of purity are employed.
A good working mixture of these materials may be taken as being loo parts by weight of lime with 68 parts c arbide.
In the former, the anthracite and lime are ground and carefully mixed in the right proportions to suit the chemical actions involved.
The essence of this process is that the coke and lime are only heated to the point of combination, and are not 3 to 82 5 to 72 13 to 75 4 to 22 5 to 13 colours.
In the generation of acetylene from calcium carbide and water, all that has to be done is to bring these two compounds into contact, when they mutually react upon each other with the formation of lime and acetylene, while, if there be sufficient water present, the lime combines with it to form calcium hydrate.
The run carbide, however, is never so rich as the ingot carbide, since an excess of lime is nearly always used in the mixture to act as a flux, and this remaining in the carbide lowers its gasyielding power.
Among manufactures are lumber, spokes, handles, waggons, lime, evaporated fruit and flour.
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 output of lime in 1908 was 107,813 tons, valued at $566,022.
On the east of the town is the Maliebaan or Mall, consisting of an ancient triple avenue of lime trees, now largely replanted.
The Nahuatl lapidaries had at hand many varieties of workable and beautiful stone - onyx, marble, limestone, quartz and quartz crystal, granite, syenite, basalt, trachyte, rhyolite, diorite and obsidian, the best of material prepared for them by nature; while the Mayas had only limestone, and hard, tenacious rock with which to work it, and timber for burning lime.
This is neutralized with lime and redistilled in order to remove the acetic acid.
The aqueous product is then dehydrated with potash or lime.
Filtration in the chemical laboratory is commonly effected by the aid of a special kind of unsized paper, which in the more expensive varieties is practically pure cellulose, impurities like feric oxide, alumina, lime, magnesia and silica having been removed by treatment with hydrochloric and hydrofluoric acids.
The citron, sour orange, lemon and lime grow wild; but the apple and peach do not come to perfection.
Coloured and white paper, ready-made clothing, cellulose, tobacco, lime and liqueurs are the chief manufactures, while a considerable export trade is done down the Main in wood, cattle and wine.
In northern Estremadura in Spain and Alemtezo in Portugal there are vein deposits of phosphate of lime.
Blackness, on the coast farther east, was the seaport of Linlithgow till the rise of Bo'ness, but its small export trade now mainly consists of coal, bricks, tiles and lime.
In the neighbourhood of Glens Falls are valuable quarries of black marble and limestone, and lime, plaster and Portland cement works.
Limestone is abundant, and the city has various manufactures, including lime, foundry and machine-shop products, agricultural implements, planing-mill products, engines, steam shovels, dredges, pianos and silks.
Wauwatosa has important manufactures, including machinery, brick, lime, beer, chemicals and wooden-ware, and extensive market gardens and nurseries and valuable stone quarries.
Lime is obtained from the Chalk and Greensand formations.
It is used in China, mixed with food, to give to mulch cows to improve the quality and increase the quantity of milk, and when mixed with lime as a size to impart a gloss to walls.
Calcium oxide or lime has been known from a very remote period, and was for a long time considered to be an elementary or undecomposable earth.
Davy, inspired by his successful isolation of the metals sodium and potassium by the electrolysis of their hydrates, attempted to decompose a mixture of lime and mercuric oxide by the electric current; an amalgam of calcium was obtained, but the separation of the mercury was so difficult that even Davy himself was not sure as to whether he had obtained pure metallic calcium.
Electrolysis of lime or calcium chloride in contact with mercury gave similar results.
The monoxide and its hydrate are more familiarly known as lime (q.v.) and slakedlime.
It is now manufactured by heating lime and carbon in the electric furnace (see Acetylene).
Calcium phosphide, Ca 3 P 2, is obtained as a reddish substance by passing phosphorus vapour over strongly heated lime.
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.
Calcium monosulphide, CaS, a white amorphous powder, sparingly soluble in water, is formed by heating the sulphate with charcoal, or by heating lime in a current of sulphuretted hydrogen.
The sulphydrate or hydrosulphide, Ca(SH)2, is obtained as colourless, prismatic crystals of the composition Ca(SH) 2.6H 2 O, by passing sulphuretted hydrogen into milk of lime.
The disulphide, CaS2, and pentasulphide, CaS 5, are formed when milk of lime is boiled with flowers of sulphur.
Calcium sulphite, CaSO 3, a white substance, soluble in water, is prepared by passing sulphur dioxide into milk of lime.
This solution with excess of sulphur dioxide yields the "bisulphite of lime" of commerce, which is used in the "chemical" manufacture of woodpulp for paper making.
With regard to the fine boulevards of the Upper Town, it may be mentioned that about 1765 they were planted with the double row of lime trees which still constitute their chief ornament by Prince Charles of Lorraine while governing the Netherlands for his sister-in-law, the empress Maria Theresa.
It is obtained by the dry distillation of nitrogenous vegetable and animal products; by the reduction of nitrous acid and nitrites with nascent hydrogen; and also by the decomposition of ammonium salts by alkaline hydroxides or by slaked lime, the salt most generally used being the chloride (sal-ammoniac, q.v.) thus 2NH 4 C1+Ca(OH) 2 =CaC1 2 +2H 2 O+2NH 3.
Many of the ammonium salts are made from the ammoniacal liquor of gas-works, by heating it with milk of lime and then absorbing the gas so liberated in a suitable acid.
Almost the only manufactures of any importance are the distillation of arrack, which is principally carried on by Chinese, the burning of lime and bricks, and the making of pottery.
It is now obtained from the ammoniacal liquor of gas works by distilling the liquor with milk of lime and passing the ammonia so obtained into hydrochloric acid.
A strong north-west wind, at such times, is of incalculable value to the farmer."8 Other gall-making dipterous flies are members of the family Trypetidae, which disfigure the seed-heads of plants, and of the family Mycetophilidae, such as the species Sciara tilicola, 9 Low, the cause of the oblong or rounded green and red galls of the young shoots and leaves of the lime.
Aix has thermal springs, remarkable for their heat and containing lime and carbonic acid.
Lipki district (from the lipki or lime trees, destroyed in 1833) is of recent origin, and is mainly inhabited by the well-to-do classes.
The original material was a fine clay, sometimes with more or less of sand or ashy ingredients, occasionally with some lime; and the bedding may be indicated by alternating bands of different lithological character, crossing the cleavage faces of the slates, and often interrupting the cleavage, or rendering it imperfect.
It may be readily recognized by the white precipitate which it forms when passed through lime or baryta water.
There are a number of warm mineral springs, containing principally salts of lime, used with success by both Arabs and Europeans in several kinds of disease.
The water, which is at boiling point, falls into natural basins of a creamy white colour, formed by the deposit of carbonate of lime.
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.
It is readily soluble in water, and on evaporation in a vacuum over caustic lime it deposits colourless, rhombohedral crystals of 2KHS.H 2 0.
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.
Good whisky is made in Maryland and in parts of Pennsylvania from rye, but all efforts in other states to produce from Indian corn a whisky equal to the Bourbon have failed, and it is probable that the quality of the Bourbon is largely due to the character of the Kentucky lime water and the Kentucky yeast germs. The average annual product of the state from 1880 to 1900 was about 20,000,000 gallons; in 1900 the product was valued at $9,786,527; in 1905 at $11,204,649.
The dwarf-palm, orange, lime, and olive grow in the warmer tracts; and on the higher grounds the thorn-apple, pomegranate, myrtle, esparto and heaths flourish.
When chewed a small piece is wrapped up in a leaf of the betel vine or pan, with a pellet of shell lime or chunam; and in some cases a little cardamom, turmeric or other aromatic is added.
There is a small dock, and phosphate of lime is extensively dug in the neighbourhood and exported for use as manure.
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.
Glass and other sands and gravel ($13,270,032), lime ($11,091,186), phosphate rock ($10,653,558), salt ($7,553,632), natural mineral waters ($7,287,269), sulphur ($6,668,215, almost wholly from Louisiana), slate ($6,316,8 I7), gypsum ($4,138,560), clay ($2,599,986), asphalt ($1,888,881), talc and soapstone ($1,401,222), borax ($975,000, all from California), and pyrite ($857,113) were the next most important products in 1908.
Of building-stone, clay, cement, lime, sand and salt, the countrys supply was estimated by the National Conservation Commission of 1908 to be ample.
They may be extracted by exhausting the plant-tissues with a dilute acid, and precipitating the bases with potash, soda, lime or magnesia.
Large quantities of seaweed as well as lime and marl are available for manure.
The crofters' houses have been rebuilt of stone and lime, and are superior to those in most parts of the Highlands.
In his widely used method for the quantitative determination of carbonic acid the gaseous mixture is shaken up with baryta or lime water of known strength and the change in alkalinity ascertained by means of oxalic acid.
These parcels, he said, "contained quicklime, for the purpose of absorbing any moisture and keeping the boxes quite dry, the lime being packed in paper for the sake of cleanliness.
Slugs are often destructive to the young shoots, but may be checked by a few sprinklings of soot or lime.
The once flourishing cloth and woollen trades have declined, but there are large breweries, roperies, potteries, and, in the neighbourhood, marble, granite, asphalt and lime works.
The trade is mostly in coal and lime and the exports are chiefly agricultural.
South of the Cotton Belt is the Lime Sink Region, which includes Miller, Baker, Mitchell, Colquitt and Worth counties, the northern portions of Decatur, Grady, Thomas, Brooks and Lowndes, the eastern parts of Dooly and Lee, and the eastern portions of Berrien, Irwin, Wilcox, Dodge, and some parts of Burke, Screven and Bulloch.
Here the prevailing soils are grey and sandy with a subsoil of loam, but they are less fertile than those of the Lime Sink or Cotton Belts.
Thus Sainte Claire Deville prepared it as a very hard substance of steel-grey colour, capable of taking a high polish, by strong ignition of chromic oxide and sugar charcoal in a lime crucible.
Moissan (Comptes rendus, 1893, 116, p. 349; 1894, 119, p. 185) reduces the sesquioxide with carbon, in an electric furnace; the product so obtained (which contains carbon) is then strongly heated with lime, whereby most of the carbon is removed as calcium carbide, and the remainder by heating the purified product in a crucible lined with the double oxide of calcium and chromium.
Flour is manufactured in Lexington and lime in the vicinity.
Other industrial establishments of importance include petroleum refineries, ship-yards, brick, stone and lime works, saddlery and harness factories, lithographing establishments, patent medicine works, chemical works, and copper smelters and refineries.
Greenhithe, on the banks of the Thames, has large chalk quarries in its neighbourhood, from which lime and cement are manufactured.
Carthage is a jobbing centre for a fruit and grain producing region; live-stock (especially harness horses) is raised in the vicinity; and among the city's manufactures are lime, flour, canned fruits, furniture, bed springs and mattresses, mining and quarrying machinery, ploughs and woollen goods.
Dredging, however, is prosecuted, the sand being sent inland, being useful as a manure through the carbonate of lime with which it is impregnated.
The matrix is the lime or cement, whose chemical action with the added water causes the concrete to solidify; and the aggregate is the broken stone or hard material which is embedded in the matrix.
The oldest of all the matrices is lime, and many splendid examples of its use by the Romans still exist.
It has been to a great extent superseded by Portland cement, on account of the much greater strength of the latter, though lime concrete is still used in many places for dry foundations and small structures.
To be of service the lime should be what is known as "hydraulic," that is, not pure or "fat," but containing some argillaceous matter, and should be carefully slaked with water before being mixed with the aggregate.
To ensure this being properly done, the lumps of lime should be broken up small, and enough water to slake them should be added, the lime then being allowed to rest for about forty-eight hours, when the water changes the particles of quicklime to hydrate of lime, and breaks up the hard lumps into a powder.
The hydrated lime, after being passed through a fine screen to sort out any lumps unaffected by the water, is ready for concrete making, and if not required at once should be stored in a dry place.
When lime is used as a matrix, certain natural earths such as pozzuolana or trass, or, failing these, powdered bricks or tiles, may be used instead of sand with great advantage.
They have the property of entering into chemical combination with the lime, forming a hard setting compound, and increasing the hardness of the resulting concrete.
In proportioning the quantities of matrix to aggregate the ideal to be aimed at is to get a concrete in which the voids or air-spaces shall be as small as possible; and as the lime or cement is usually by far the most expensive item, it is desir able to use as little of it as is consistent with strength.
When natural flint gravel containing both stones and sand is used, it is usual to mix so much gravel with so much lime or cement.
In hand mixing it is usual to measure out from gauge boxes the sand, stones and cement or lime in a heap on a wooden platform.
The same praise cannot, however, be given to lime concrete.
Even though the best hydraulic lime be used it is wise to confine it to places where it is not exposed to the air, or to running water, and indeed for important structures the use of lime should be avoided.
Good Portland cement is so much stronger than any lime that there are few situations where it is not cheaper as well as better to use the former, because, although cement is the more expensive matrix, a smaller proportion of it will suffice for use.
Lime should never be used in work exposed to sea-water, or to water containing chemicals of any kind.
The matter was carefully investigated, and it was found that the sulphate of magnesia in the sea-water has a decomposing action on Portland cements, especially those which contain a large proportion of lime or even of alumina.
But to ensure the permanence of structures in sea-water the great object is to choose a cement containing as little lime and alumina as possible, and free from sulphates such as gypsum; and more important still to proportion the sand and stones in the concrete in such a way that the structure is practically non-porous.
Others, like Ford's silicate of limestone, are practically lime mortars of excellent quality, which can be carved and cut like a sandstone of fine quality.
Natural soils consist of substances derived from the decomposition of various kinds of rocks, the bulk consisting of clay, silica and lime, in various proportions.
Argillaceous or clay soils are those which contain a large percentage (45-50) of clay, and a small percentage (5 or less) of lime.
Loamy soils contain a considerable quantity (30-45%) of clay, and smaller quantities of lime, humus and sand.
Manly soils are those which contain a considerable percentage (10-20) of lime, and are called clay marls, loamy marls and sandy marls, according as these several ingredients preponderate.
Calcareous soils, which may also be heavy, intermediate or light, are those which contain more than 20% of lime, their fertility depending on the proportions of clay and sand which enter into their composition; they are generally cold and wet.
The chief point to be borne in mind in making these mixtures is not to combine in the same compost any bodies that are antagonistic in their nature, as for example lime and ammonia.
In a natural state it is obtained from bones, guano and wood ashes; and in an artificial condition from basic slag or Thomas's phosphate, coprolites and superphosphate of lime.
Lime in the caustic state is beneficially applied to soils which contain an excess of inert vegetable matter, and hence may be used for the improvement of old garden soils saturated with humus, or of peaty soils not thoroughly reclaimed.
Gypsum, or sulphate of lime, applied as a top-dressing at the rate of 2 to 3 cwt.
Gas lime, after it has been exposed to the air for a few months is an excellent manure on heavy soils.
In the Carboniferous Limestone series, the purer kinds of limestone are used for the manufacture of lime, bleaching powder and similar products, also as a flux in the smelting of iron; some of the less pure varieties are used in making cement.
Thomas, who showed that, in the presence of a slag rich in lime, the whole of the phosphorus could be removed readily.
Impurities.-The properties of iron and steel, like those of most of the metals, are profoundly influenced by the presence of small and sometimes extremely small quantities of certain impurities, of which the most important are phosphorus and sulphur, the former derived chiefly from apatite (phosphate of lime) and other minerals which accompany the iron ore itself, the latter from the pyrite found not only in most iron ores but in nearly all coal and coke.
The desulphurizing effect of this transfer of the sulphur from union with iron to union with calcium is due to the fact that, whereas iron sulphide dissolves readily in the molten metallic iron, calcium;sulphide, in the presence of a slag rich in lime, does not, but by preference enters the slag, which may thus absorb even as much as 3% of sulphur.
The duty of the limestone (CaCO 3) is to furnish enough lime to form with the gangue of the ore and the ash of the fuel a lime silicate or slag of such a composition (1) that it will melt at the temperature which it reaches at about level A, of fig.
Of these the silica and alumina are chiefly those which the gangue of the ore and the ash of the fuel introduce, whereas the lime is that added intentionally to form with these others a slag of the needed physical properties.
In the basic Bessemer process, also, unforeseen variations in the siliconcontent are harmful, because the quantity of lime added should be just that needed to neutralize the resultant silica and the phosphoric acid and no more.
Of these the first escapes immediately as a gas, and the others unite with iron oxide, lime, or other strong base present to form a molten silicate or silica-phosphate called " cinder " or " slag," which floats on the molten or pasty metal.
In the basic Bessemer process phosphorus is readily removed by oxidation, because the product of its oxidation, phosphoric acid, P 2 O 5, in the presence of an excess of base forms stable phosphates of lime and iron which pass into the slag, making it valuable as an artificial manure.
The slag, in order that it may have such an excess of base that this will retain the phosphoric acid as fast as it is formed by the oxidation of the phosphorus of the pig iron, and prevent it from being re-deoxidized and re-absorbed by the iron, should, according to von Ehrenwerth's rule which is generally followed, contain enough lime to form approximately a tetra-calcic silicate, 4CaO,S10 2 with the silica which results from the oxidation of the silicon of the pig iron and tri-calcic phosphate, 3CaO,P205, with the phosphoric acid which forms. The danger of this " rephosphorization " is greatest at the end of the blow, when the recarburizing additions are made.
This lime is charged in the form of common quicklime, CaO, resulting from the calcination of a pure limestone, CaCO 3, which should be as free as possible from silica.
The usual composition of this slag is iron oxide, i o to 16%; lime, 40 to 50%; magnesia, 5%; silica, 6 to 9%; phosphoric acid, 16 to 20%.
The lining of the converter is made of 90% of the mixture of lime and magnesia which results from calcining dolomite, (Ca,Mg)CO i, at a very high temperature, and 10% of coal tar freed from its water by heating.
The removal of the greater part of the phosphorus takes place after the carbon has been oxidized and the flame has consequently " dropped," probably because the lime, which is charged in solid lumps, is taken up by the slag so slowly that not until late in the operation does the slag become so basic as to be retentive of phosphoric acid.
At the Carnegie works Mr Monell gets the two dephosphorizing conditions, low temperature and basicity of slag, early in the process, by pouring his molten but relatively cool cast iron upon a layer of pre-heated lime and iron oxide on the bottom of the open-hearth furnace.
The lime and iron oxide melt, and, in passing up through the overlying metal, the iron oxide very rapidly oxidizes its phosphorus and thus drags it into the slag as phosphoric acid.
In the first stage the phosphorus is removed from the molten steel by oxidizing it to phosphoric acid, P205, by means of iron oxide contained in a molten slag very rich in lime, and hence very basic and retentive of that phosphoric acid.
This slag is formed by melting lime and iron oxide, with a little silica sand if need be.
Floating on top of the molten metal, it rapidly oxidizes its phosphorus, and the resultant phosphoric acid combines with the lime in the overlying slag as phosphate of lime.
Next the metal is covered with a very basic slag, made by melting lime with a little silica and fluor spar.
We still use the old familiar purifying agents, iron oxide, lime and nascent calcium.
At the same time, hot springs, containing abundant carbonate of lime in solution, produced deposits of travertine at various points.
Limestone appears in various places, and in the north-east a light grey marble is quarried for lime.
The mineral products of the district also include lignite, copper, manganese, vitriol, lime, gypsum, volcanic stones (used for millstones) and slates.
These plateaus, with an average elevation of Boo to 1000 ft., are mostly covered with forests of oak, beech and lime, and are deeply cut by river valleys, some being narrow and craggy, and others broad, with gentle slopes and marshy bottoms. Narrow ravines intersect them in all directions, and they often assume, especially in the east, the character of wild, impassable, woody and marshy tracts.
The lime appears in groves only in the east (Memel, Pripet, Lublin).
The district abounds in coal, lime and ironstone.
At Llangollen are linen and woollen manufactures, and near are collieries, lime and iron works.
The industrial establishments comprise cotton-mills, print-works, paper-mills, foundries, and brick and lime works.
Of other minerals (with the exceptions of coal, iron and salt treated below) nickel and antimony are found in the upper Harz; cobalt in the hilly districts of Hesse and the Saxon Erzgebirge; arsenic in the Riesengebirge; quicksilver in the Sauerland and in the spurs of the Saarbrucken coal hills; graphite in Bavaria; porcelain clay in Saxony and Silesia; amber along the whole Baltic coast; and lime and gypsum in almost all parts.
Besides chemical manufactures, there are chalk, lime, cement and brick works and a shipbuilding yard.
The by-products of the citrus-essences, citrate of lime, &c. are also of some importance.
C. i is on the earliest dwellings of man; C. 2 on systems of Thales, Heraclitus, Democritus, &c.; c. 3 on bricks; c. 4 on sand; c. 5 on lime; c. 6 on pozzolana; c. 7 on kinds of stone for building; c. 8 on methods of constructing walls in stone, brick, concrete and marble, and on the materials for stucco; c. 9 on timber, time for felling it, seasoning, &c.; and c. to on the fir trees of the Apennines.
Many of the Egyptian rocks in the desert areas and at the cataracts are coated with a highly polished film, of almost microscopic thinness, consisting chiefly of oxides of iron and manganese with salts of magnesia and lime.
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.
At specific gravity 1.2461 a Up to the time then that the water became concentrated to specific gravity 1.218 only 0.150 of deposit had formed, and that chiefly composed of lime and iron, but between specific gravity I 218 and 1.313 there is deposited a mixture of Of this about 95% is sodium chloride.
Sometimes, to get rid of these impurities, the brine is treated in a large tub-`(bessoir) with lime; on settling it becomes clear and colourless, but the dissolved lime forms a skin on its surface in the pan, retards the evaporation and impedes the crystallization.
Some species belonging to the families Squamariaceae and Corallinaceae grow attached through their whole length and breadth, and are often encrusted with lime.
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.
This slakes violently with water, giving slaked lime, which can be made into a smooth paste with water and mixed with sand to form common mortar.
The setting of the mortar is due to the drying of the lime (a purely physical phenomenon, no chemical action occurring between the lime and the sand).
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.
Mortar made from pure or "fat" lime cannot withstand the action of water, and is only used for work done above water-level.
If, however, such "fat" lime is mixed in the presence of water, not with sand but with silica in an active form, i.e.
The mixture of the lime and active silica or silicate is a pozzuolanic cement.
The simplest of all pozzuolanic cements would be a mixture of pure lime and hydrated silica, but though the latter is prepared artificially for various purposes, it is too expensive to be used as a cement material.
The slag, which must contain a high percentage of lime, is granulated by being run while fused into abundance of water.
This potential energy becomes kinetic when the slag is brought into contact with lime in the presence of water, and causes the formation of a true hydraulic silicate of lime.
The usual proportions are three of slag to one of slaked lime by weight.
They are not usually manufactured by the careful grinding together of the pozzuolana and the lime, but are mixed roughly, a great excess of pozzuolana being employed.
This excess does no harm, for that part which fails to unite with the lime serves as a diluent, much as does sand in mortar.
Good hydraulic mortars may be made from lime mixed with furnace ashes or burnt clay as the pozzuolanic constituent.
Cements of the Portland type differ in kind from those of the pozzuolanic class; they are not mechanical mixtures of lime and active silica ready to unite under suitable conditions, but consist of definite chemical compounds of lime and silica and lime and alumina, which, when mixed with water, combine therewith, forming crystalline substances of great mechanical strength, and capable of adhering firmly to clean inert material, such as stone and sand.
The commonest of such substances in England are chalk and clay, but where local conditions demand it, limestone, marl, shale, slag or any similar material may be used, provided that the correct proportions of lime, silica and alumina are maintained.
Next in antiquity to hydraulic lime is Roman cement, prepared by heating an indurated marl occurring naturally in nodules.
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.
Although Portland cement is later in date than either Roman cement or hydraulic lime, yet on account of its greater industrial importance, and of the fact that, being an artificial product, it is of approximately uniform composition and properties, it may conveniently be treated of first.
The kilns commonly employed are "chamber kilns," circular structures not unlike an ordinary running lime kiln, but having the top closed and connected at the side with a wide flue in which the slurry is exposed to the hot products of combustion from the kiln.
A possible alternative is to burn the limestone first and mix the resulting lime with clay, the mixture being burned as before.
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 material must be picked out, as such underburnt stuff contains free lime or unsaturated lime compounds.
Thus the silica may range from 19 to 27%, the alumina and ferric oxide jointly from 7 to 14%, the lime from 60 to 67%.
All such variations are permissible provided that the quantity of silica and alumina is sufficient to saturate the whole of the lime and to leave none of it in a "free" condition, likely to cause the cement to expand after setting.
Other things being equal, the higher the percentage of lime within the limits indicated above the stronger is the cement, but such highly limed cement is less easy to burn than cement containing about 62% of lime; and unless the burning is thorough and the raw materials are intimately mixed, the cement is apt to be unsound.
The function of the ferric oxide present in ordinary cement is little more than that of a flux to aid the union of silica, alumina and lime in the clinker; its role in the setting of the cement is altogether secondary.
It will be observed that in the hydration of tricalcium silicate, the main constituent of Portland cement, a large portion of the lime appears as calcium hydroxide, i.e.
Hydraulic Lime is a cement of the Portland as distinct from the pozzuolanic class.
The most typical hydraulic lime is that known as Chaux du Theil, made from a limestone found at Ardeche in France.
It contains but little alumina and oxide of iron, which are the constituents generally necessary to bring about the union of silica and lime to form a cement, but in spite of this the silica is so finely divided and so well distributed that it unites readily with the lime when the limestone is burned at a sufficiently high temperature.
In France this slaking is conducted systematically by the makers, the freshly burned lime being sprinkled with water and stored in large bins where slaking proceeds slowly and regularly until the whole of the surplus uncom bined lime is slaked and rendered harmless, while the cementitious compounds, notably tricalcium silicate, remain untouched.
In English practice hydraulic lime is slaked by the user.
The product may then be regarded as a cement of the Portland class mixed with slaked lime.