To the last is credited the first introduction of covered crucibles to protect the molten glass from the products of burning coal.
"From molten metal to the tempered steel of a blade," Eden replied.
A bottle mould rises and envelops the mass of molten glass.
In such cases the molten rock cannot have been homogeneous, and as it flowed along the ground the different portions of it were drawn out into long parallel streaks.
The earth has an enormous molten core that contains vast amounts of energy.
The latter are made by dipping a small mass of molten colourless glass into an iron cup around the inner wall of which short lengths of white cane have been arranged at regular intervals.
If before this application of the molten glass the metallic leaf, whilst resting on the thin film of blown glass, was etched with a sharp point, patterns, emblems, inscriptions and pictures could be embedded and rendered permanent by the double coating of glass.
The examination of small test-pieces of the glass withdrawn from the crucible by means of an iron rod having shown that the molten mass is free from bubbles, the stirring process may be begun, the object of this manipulation being to render the glass as homogeneous as possible and to secure the absence of veins or striae in the product.
His silver eyes were molten, his rugged jaw line shaded by two days. growth.
You may melt your metals and cast them into the most beautiful moulds you can; they will never excite me like the forms which this molten earth flows out into.
7 Vestiges of the Molten Globe (London, 1875).
The heat is then raised in (relative) absence of air, when the two elements named unite into sulphur-dioxide, while a regulus of molten lead remains.
Imitations of natural stones were made by stirring together in a crucible glasses of different colours, or by incorporating fragments of differently coloured glasses into a mass of molten glass by rolling.
It is like molten glass cooled but not congealed, and the few motes in it are pure and beautiful like the imperfections in glass.
The process consisted in spreading the leaf on a thin film of blown glass and pressing molten glass on to the leaf so that the molten glass cohered with the film of glass through the pores of the metallic leaf.
De Nehou's process of rolling molten glass poured on an iron table rendered the manufacture of very large plates possible.
As the molten metal is run in, the upward thrust on the outside mould, when the level has reached PP', is the weight of metal in the volume generated by the revolution of APQ; and this, by a theorem of Archimedes, has the same volume as the cone ORR', or rya, where y is the depth of metal, the horizontal sections being equal so long as y is less than the radius of the outside FIG.
The duty on flint-glass was imposed on the molten glass in the crucibles and on the unfinished goods.
Thus the dimensions of the largest glass tanks greatly exceed those of the largest steel furnaces; glass furnaces containing up to 250 tons of molten sible to work glass-tanks continuously for many months together; on the other hand, glass is not readily freed from foreign bodies that may become admixed with it, so that the absence of detachable particles is much more essential in glass than in steel melting.
Most metals when molten are capable of dissolving at least small proportions of carbon, which, in general, leads to a deterioration in metallicity, except in the case of iron, which by the addition of small percentages of carbon gains in elasticity and tensile strength with little loss of plasticity.
In this way the crucible is gradually filled with a mass of molten glass, which is, however, [[Table I]].- Optical Properties.
A sufficient weight of molten glass to form a bottle is gathered and placed in a funnel-shaped vessel which serves as a measure, and gives access to the mould which shapes the outside of the neck.
All the earlier attempts in this direction failed on account of the difficulty of bringing the glass to the machines without introducing air-bells, which are always formed in molten glass when it is ladled or poured from one vessel into another.
The famous cameo glass was formed by covering a mass of molten glass with one or more coatings of a differently coloured glass.
The molten sulphur accumulates on the sole, whence it is from time to time run out into a square stone receptacle, from which it is ladled into damp poplar-wood moulds and so brought into the shape of truncated cones weighing 110 to 130 lb each.
Guinand, towards the end of the 18th century, by introducing the process of stirring the molten glass by means of a cylinder of fireclay.
GALVANIZED IRON, sheet iron having its surface covered with a thin coating of zinc. In spite of the name, galvanic action has often no part in the production of galvanized iron, which is prepared by dipping the iron, properly cleaned and pickled in acid, in a bath of molten zinc. The hotter the zinc the thinner the coating, but as a high temperature of the bath is attended with certain objections, it is a common practice to use a moderate temperature and clear off the excess of zinc by passing the plates between rollers.
The common monoclinic variety is obtained by allowing a crust to form over molten sulphur by partially cooling it, and then breaking the crust and pouring off the still liquid portion, whereupon the interior of the vessel will be found coated with long needles of this variety.
Thereupon Ormazd will hold a judicium universale, in the form of a general ordeal, a great test of all mankind by fire and molten metal, and will judge strictly according to justice, punish the wicked, and assign to the good the hoped-for reward.
The leg is formed and a small lump of molten glass is attached to its extremity to form the foot.
Boron dissolves in molten aluminium, and on cooling, transparent, almost colourless crystals are obtained, possessing a lustre, hardness and refractivity near that of the diamond.
Its specific gravity is about 9; it is sparingly soluble in water, but readily dissolves in acids and molten alkalis.
They are next steeped in a bath, first of molten ferruginous, then of pure tin.
18), of stone pillars to the Canaanite Baal, of the Asherah-pole, molten images and the worship of other gods than Yahweh (Ex.
Molten tin is then poured in, a little powdered salammoniac added, and the tin spread over the inside with a bunch of tow.
In Cumberland, Northumberland, Durham and latterly the United States, the reverberatory furnace is used only for roasting the ore, and the oxidized ore is then reduced by fusion in a low, square blastfurnace (a "Scottish hearth furnace") lined with cast iron, as is also the inclined sole-plate which is made to project beyond the furnace, the outside portion (the "work-stone") being provided with grooves guiding any molten metal that may be placed on the "stone" into a cast iron pot; the "tuyere" for the introduction of the wind was, in the earlier types, about half way down the furnace.
The metal is dimorphous: by cooling molten tin at ordinary air temperature tetragonal crystals are obtained, while by cooling at a temperature just below the melting point rhombic forms are produced, When exposed for a sufficient time to very low temperatures (to - 39° C. for 14 hours), tin becomes so brittle that it falls into a grey powder, termed the grey modification, under a pestle; it indeed sometimes crumbles into powder spontaneously.
It has been also suggested that the word might mean a "molten image" from the sense of "pour."
The character of molten sulphur has been mainly elucidated by the researches of A.
de la Bastie's process of " toughening " glass consisted in dipping glass, raised to a temperature slightly below the melting-point, into molten tallow.
Celebrate after a long hike with a hot molten lava cake.
The mere act of coiling an exact weight of molten glass round the end of a rod 4 ft.
A vase decorated with these simple or complex canes is produced by embedding short lengths of the cane on the surface of a mass of molten glass and blowing and fashioning the mass into the required shape.
If the section of the finished tube is to be a triangle, with the enamel and bore at the base, the molten mass is pressed into a V-shaped mould before it is pulled out.
An effort at a more direct mechanical process is embodied in the inventions of Foucault which are at present being developed in Germany and Belgium; in this process the glass is drawn from the molten bath in the shape of flat sheets, by the aid of a bar of iron, previously immersed in the glass, the glass receiving its form by being drawn through slots in large fire-bricks, and being kept in shape by rapid chilling produced by the action of air-blasts.
Molten glass is spread upon a large iron plate of the required shape and dimensions.
Threads of coloured molten glass were spirally coiled round the body, and, whilst still viscid, were dragged into zigzags with a metal hook.
The retorts are charged with molten sulphur from an upper reservoir, which is kept at the requisite temperature by means of the lost heat of the retort fires.
The crucibles or pots used for the production of optical glass very closely resemble those used in the manufacture of flint glass for other purposes; they are " covered " and the molten materials are thus protected from the action of the furnace gases by the interposition of a wall of fireclay, but as crucibles for optical glass are used for only one fusion and are then broken up, they are not made so thick and heavy as those used in flint-glass making, since the latter remain in the furnace for many weeks.
For this purpose a cylinder of fireclay, provided with a square axial hole at the upper end, is heated in a small subsidiary furnace and is then introduced into the molten glass.
Cane is produced from a solid mass of molten glass, tube from a mass hollowed by blowing.
Touches of colour may be added to vessels in course of manufacture by means of seals of molten glass, applied like sealing-wax; or by causing vessels to wrap themselves round with threads or coils of coloured glass.
When the first ball or " gathering 'T has cooled sufficiently, the whole is again dipped into the molten glass and a further layer adheres to the pipe-end, thus forming a larger ball.
In an American process the glass is drawn direct from the molten mass in the tank in a cylindrical form by means of an iron ring previously immersed in the glass, and is kept in shape by means of special devices for cooling it rapidly as it leaves the molten bath.
The funnel is removed, and the plunger, neck-mould and the mass of molten glass attached to the neck are inverted.
Compressed air admitted through the plunger forces the molten glass to take the form of the bottle mould and completes the bottle.
As soon as a blowing iron is in connexion with an air jet, the sections of the mould close upon the molten glass, and the compressed air forces the glass to take the form of the mould.
Alumina itself is so refractory that it cannot be melted save by the oxyhydrogen blowpipe or the electric arc, and except in the molten state it is not susceptible of decomposition by any chemical reagent.
These plates float on the partially molten rocks of the upper mantle.
She stepped closer to him as she had in their dream, gazing up into his molten silver eyes. He'd gone to Hell for Hannah and confronted Death for her. He'd killed demons to protect her and defied his family to find – and keep – her.
The former contains a mixture of semi-solid and molten metal, which is raked out into iron ladles and cast into plates of 66 to 77 lb weight, to be sold as "spelter."
It fuses at 415° C. and under ordinary atmospheric pressure boils at 1040° C. Its vapour density shows that it is monatomic. The molten metal on cooling deposits crystals belonging to the hexagonal system, and freezes into a compact crystalline solid, which may be brittle or ductile according to circumstances.
Zinc is largely used for "galvanizing" iron, sheets of clean iron being immersed in a bath of the molten metal and then removed, so that a coat of zinc remains on the iron, which is thereby protected from atmospheric corrosion.
for the production of calcium carbide) in which a portion of the charge is first actually fused, and then maintained in the molten condition by the current passing through it, while the reaction between further portions of the charge is proceeding.
But they are gradually being filled up there and will Ltimately disappear under the sheets of molten rock that from me to time rush into them from above.
THE GOLDEN CALF, a molten image made by the Israelites when Moses had ascended the Mount of Yahweh to receive the Law (Ex.
Let us suppose that a molten mixture of two substances A and B, which at a sufficiently high temperature form a uniform liquid, and which do not combine to form definite compounds, is slowly cooled until it becomes wholly solid.
Other metals which find application in the metallurgy of gold by virtue of their property of extracting the gold as an alloy are lead, which combines very readily when molten, and which can afterwards be separated by cupellation, and copper, which is separated from the gold by solution in acids or by electrolysis; molten lead also extracts gold from the copper-gold alloys.
Molten alloys containing more than 80% of silver deposit on cooling the alloy AuAgs, little gold remaining in the mother liquor.
The second process depends upon the fact that, if chlorine be led into the molten alloy, the base metals and the silver are converted into chlorides.
The alloy, after the preliminary refining, is granulated by being poured, while molten, in a thin stream into cold water which is kept well agitated.
In the liquation process the ore is heated in inclined cylindrical retorts, and the molten metal is tapped at the lower end; the residues being removed from the upper end.
The fusion process is preferably carried out in crucible furnaces; shaft furnaces are unsatisfactory on account of the disintegrating action of the molten bismuth on the furnace linings.
The lowest layer of the molten mass is principally metallic bismuth, the succeeding layers are a bismuth copper matte, which is subsequently worked up, and a slag.
2 9, p. 2 94), its specific gravity is 9.7 81 43; Roberts and Wrightson give the specific gravity of solid bismuth as 9.82, and of molten bismuth as to 055.
Vapour baths of iron are used in connexion with boiling anthracene (335°), anthraquinone (368°),sulphur(444°),phosphoruspentasulphide(518°); molten lead may also be used.
When the body is in this state the relative positions of the molecules are not permanently fixed, so that the body is no longer of unalterable shape: it has, assumed a plastic or molten condition.
The molten metal is poured into the moulds N, which are carried on wheels running on rails Q.
In foreign mints the molten metal is generally transferred from the crucible to the moulds by dipping crucibles or iron ladles covered with clay.
1, OP. The molten gold, which is of a pale green colour, solidifies at once in the iron moulds, and the bars can be taken out immediately.
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.
The monoxide, K 2 0, may be obtained by strongly heating the product or burning the metal in slightly moist air; by heating the hydroxide with the metal: 2KHO+2K= 2K 2 0+H 2; or by passing pure and almost dry air over the molten metal (Kiihnemann, Chem.
Fine aluminium will not burn below the temperature of molten cast iron, and previous experimenters had resorted to heating their mixtures in a crucible.
For this purpose the thermit is placed in a can on the end of a rod and plunged to the bottom of the molten metal.
Again, in the story of Micah's shrine and the removal of the sacred objects and the Levite priest by the Danites, parallel narratives have been used: the graven and molten images of Judg.
Streams of rainwater, formed by condensation of exhaled steam often mingled with volcanic ashes so as to produce mud, are known as lava d'acqua, whilst the streams of molten matter are called lava di fuoco.
The term lava is applied by geologists to all matter of volcanic origin, which is, or has been, in a molten state.
The magma, or molten lava in the interior of the earth, may be regarded as a mutual solution of various mineral silicates, charged with highly-heated vapour, sometimes to the extent of supersaturation.
242938 (1894)] passes anhydrous ammonia over heated sodium to form sodamide, which is then brought in a molten condition into contact with carbon: NaNH 2 +C = NaNC+H 2.
3 5) as the forerunner and companion of Fortuna, holding in her brazen hand huge nails, a clamp and molten lead, symbolical of fixedness and tenacity.
The first successful idea of using electricity depended on the enormous heating powers of the arc. The infusibility of alumina was no longer prohibitive, for the molten oxide is easily reduced by carbon.
It was soon discovered that the faculty of inducing dissociation possessed by the current might now be utilized with some hope of pecuniary success, but as electrolytic currents are of lower voltage than those required in electric furnaces, molten alumina again became impossible.
It has been found, however, that molten cryolite and the analogous double fluoride represented by the formula Al 2 F 6.2NaF are very efficient solvents of alumina, and that these solutions can be easily electrolysed at about 800° C. by means of a current that completely decomposes the oxide but leaves the haloid salts unaffected.
Molten cryolite dissolves roughly 30% of its weight of pure alumina, so that when ready for treatment the solution contains about the same proportion of what may be termed "available" aluminium as does the fused double chloride of aluminium and sodium.
It can also be reduced metallurgically by the action of molten iron.
The Heroult cell consists of a square iron or steel box lined with carbon rammed and baked into a solid mass; at the bottom is a cast-iron plate connected with the negative pole of the dynamo, but the actual working cathode is undoubtedly the layer of already reduced and molten metal that lies in the bath.
The molten metal has a specific gravity of 2 ï¿½ S4, that of molten cryolite saturated with alumina is 2.3 5, and that of the fluoride Al 2 F 6 2NaF saturated with alumina 1.97.
In the casting of iron, steel and brass, the addition of a trifling proportion (0.005%) removes oxide and renders the molten metal more fluid, causing the finished products to be more homogeneous, free from blow-holes and solid all through.
the molten cast iron as it issues from the blast furnace, or the pigs into which it is cast.
The history of iron may for convenience be divided into three periods: a first in which only the direct extraction of wrought iron from the ore was practised; a second which added to this primitive art the extraction of iron in the form of carburized or cast iron, to be used either as such or for conversion into wrought iron; and a third in which the iron worker used a temperature high enough to melt wrought iron, which he then called molten steel.
For brevity we may call these the periods of wrought iron, of cast iron, and of molten steel, recognizing that in the second and third the earlier processes continued in use.
This is so fusible that it melted, and, running together into a single molten mass, freed itself mechanically from the gangue," as the foreign minerals with which the ore is mixed are called.
With this method of making molten cast iron in the hands of a people already familiar with bronze founding, iron founding, i.e.
the casting of the molten cast iron into shapes which were useful in spite of its brittleness, naturally followed.
If, ignoring temporarily and for simplicity the fact that part of the carbon may exist in the state of graphite, we consider the behaviour of iron in cooling from the molten state, AB and BC give the temperature at which, for any given percentage of carbon, solidification begins, and Aa, aB, and Bc that at which it ends.
These freezing-point curves and transformation curves thus divide the diagram into 8 distinct regions, each with its own specific state or constitution of the metal, the molten state for region 1, a mixture of molten metal and of solid austenite for region 2, austenite alone for region 4 and so on.
Clearly the mushy mixture of solid austenite and molten iron of which the metal in region 2 consists cannot cohere under either the blows or the pressure by means of which welding must be done.
Slag or Cinder, a characteristic component of wrought iron, which usually contains from 0.20 to 2.00% of it, is essentially a silicate of iron (ferrous silicate), and is present in wrought iron simply because this product is made by welding together pasty granules of iron in a molten bath of such slag, without ever melting the resultant mass or otherwise giving the envelopes of slag thus imprisoned a chance to escape completely.
1), let us follow by means of the ordinate QUw the undisturbed slow cooling of molten hyper-eutectiod steel containing 1% of carbon, for simplicity assuming that no graphite forms and that the several transformations occur promptly as they fall due.
As freezing progresses, at each successive temperature reached the frozen austenite has the carbon-content of the point on Aa which that temperature abscissa cuts, and the still molten part or " mother-metal " has the carbon-content horizontally opposite this on the line AB.
This, of course, brings the final composition of the frozen austenite when freezing is complete exactly to that which the molten mass had before freezing began.
To take a second case, molten hypo-eutectoid steel of 0.20% of carbon on freezing from K to x passes in the like manner to the state of solid austenite, -y-iron with this 0.20% of carbon dissolved in it.
The freezing of molten cast iron of 2.50% of carbon goes on selectively like that of these steels which we have been studying, till the enrichment of the molten mother-metal in carbon brings its carbon-contents to B, 4.30%, the eutectic 1 carbon-content, i.e.
At this point selection ceases; the remaining molten metal freezes as a whole, and in freezing splits up into a conglomerate eutectic of (1) austenite of about 2.2% of carbon, and therefore saturated with that element, and (2) cementite; and with this eutectic is mixed the " primary " austenite which froze out as the temperature sank from v to v'.
In it the normal constituents are, for region II., molten metal+primary austenite; for region III., molten metal+primary graphite; for region IV., primary austenite; for region VII., eutectic austenite, eutectic graphite, and a quantity of pro-eutectoid graphite which increases as we pass from the upper to the lower part of the region, together with primary austenite at the left of the eutectic point B' and primary graphite at the right of that point.
1, surrounded as it is by the still molten mother-metal out of which it is growing, form a nearly continuous skeleton of very large flakes, which do break up in a most harmful way the continuity of the mass of cast iron in which they are embedded.
These two things are done simultaneously by heating and melting the ore in contact with coke, charcoal or anthracite, in the iron blast furnace, from which issue intermittently two molten streams, the iron now deoxidized and incidentally carburized by the fuel with which it has been in contact, and the mineral matter, now called " slag."
moist undried, sand, but sometimes of iron covered with a refractory coating to protect it from being melted or overheated by the molten cast iron.
If the pig iron is to follow path 2, the purification which converts it into wrought iron or steel consists chiefly in oxidizing and thereby removing its carbon, phosphorus and other impurities, while it is molten, either by means of the oxygen of atmospheric air blown through it as in the Bessemer process, or by the oxygen of iron ore stirred into it as in the puddling and Bell-Krupp processes, or by both together as in the open hearth process.
Drops of Slag Props of Iron Layer of Molten Slag- -- --:€___ Layer of Molten Iron--- * The ore and lime actually exist here in powder.
lime of the limestone and the ash of the fuel to form a complex molten silicate called the " cinder " or " slag."
Hence from this level down the only solid matter is the coke, in lumps which are burning rapidly and hence shrinking, while between them the molten iron and slag trickle, somewhat as sketched in fig.
As they collect, the molten iron is drawn off at intervals through a hole A (fig.
In fact, the molten iron is heated so far above its melting point that, instead of being run at once into pigs as is usual, it may, without solidifying, be carried even several miles in large clay-lined ladles to the mill where it is to be converted into steel.
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.
Below this level the solid charge descends easily, because it consists of coke alone or nearly alone, and this in turn because the temperature here is so high as to melt not only the iron now deoxidized and brought to the metallic state, but also the gangue of the ore and the limestone, which here unite to form the molten slag, and run freely down between the lumps of coke.
The numerous converting mills which treat pig iron made at a distance will now have the crushing burden of providing in other ways the power which their rivals get from the blast-furnace, in addition to the severe disadvantage under which they already suffer, of wasting the initial heat of the molten cast iron as it runs from the blastfurnace.
N, N, N, Ladles carrying the molten C, Receiving bin for winter stock pile.
Casting the Molten Pig Iron.
- The molten pig iron at many works is still run directly from the furnace into sand or iron moulds arranged in a way which suggests a nursing litter of pigs; hence the name " pig iron."
This pours into them the molten cast iron which it has just received directly from the blast-furnace.
(2) The carburizing incidentally carburizes the brickwork of the furnace, and thus protects it against corrosion by the molten slag.
(3) It protects the molten iron against reoxidation, the greatest stumbling block in the way of the direct processes hitherto.
Thus we have reasons enough why the blast-furnace has displaced all competing processes, without taking into account its further advantage in lending itself easily to working on an enormous scale and with trifling consumption of labour, still further lessened by the general practice of transferring the molten cast iron in enormous ladles into the vessels in which its conversion into steel takes place.
As desulphurizing seems to need the direct and energetic action of carbon on the molten iron itself, and as molten iron absorbs carbon most greedily, it is hard to see how the blast-furnace is to desulphurize without carburizing almost to saturation, i.e.
the molten cast iron direct from the blastfurnace, could be treated in the conversion process.
This " mixer " is a great reservoir into which successive lots of molten cast iron from all the blast-furnaces available are poured, forming a great molten mass of from 200 to 750 tons.
This is kept molten by a flame playing above it, and successive lots of the cast iron thus mixed are drawn off, as they are needed, for conversion into steel by the Bessemer or open-hearth process.
In like manner, if the molten iron in the mixer contains manganese, this metal unites with the sulphur present, and the manganese sulphide, insoluble in the iron, slowly rises to the surface, and as it reaches the air, its sulphur oxidizes to sulphurous acid, which escapes.
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.
Beside this their chief and easy work of oxidizing carbon, silicon and phosphorus, the conversion processes have the harder task of removing sulphur, chiefly by converting it into calcium sulphide, CaS, or manganous sulphide, MnS, which rise to the top of the molten metal and there enter the overlying slag, from which the sulphur may escape by oxidizing to the gaseous compound, sulphurous acid, S02.
In the puddling process molten cast iron is converted into wrought iron, i.e.
As the iron oxide is stirred into the molten metal laboriously by the workman or "puddler " with his hook or "rabble," it oxidizes the silicon to silica and the phosphorus to phosphoric acid, and unites with both these products, forming with them a basic iron silicate rich in phosphorus, called " puddling " or " tap cinder."
into rough 80-16 balls, each like a sponge of metallic iron particles with its pores filled with the still molten cinder.
At Hourpes, in order to save the expense of this remelting, the molten cast iron as it comes from the blast-furnace is poured directly into the puddling furnace, in large charges of about 2200 lb, which are thus about four times as large as those of common puddling furnaces.
In this process molten pig iron with much silicon but little sulphur has its silicon oxidized to silica and thus slagged off, by means of a blast of air playing on the iron through a blanket of burning coke which covers it.
The coke thus at once supplies by its combustion the heat needed for melting the iron and keeping it hot, and by itself dissolving in the molten metal returns carbon to it as fast as this element is burnt out by the blast, so that the " refined " cast iron which results, though still rich in carbon and therefore easy to melt in the puddling process, has relatively little silicon.
- Bessemer Converter, of molten pig iron, which turned down in position to receive sometimes weighs as much and discharge the molten metal.
The oxygen of the blast having been thus taken up by the molten metal, its nitrogen issues from the mouth of the converter as a pale spark-bearing cone.
In making very low-carbon steel this recarburizing proper is not needed; but in any event a considerable quantity of manganese must be added unless the pig iron initially contains much of that metal, in order to remove from the molten steel the oxygen which it has absorbed from the; blast, lest this make it redshort.
If, on the other hand, the carbon-content is to be raised, then carbon and manganese are usually added together in the form of a manganiferous molten pig iron, called spiegeleisen, i.e.
" mirror-iron," from the brilliancy of its facets, and usually containing somewhere about 12% of manganese and 4% of carbon, though the proportion between these two elements has to be adjusted so as to introduce the desired quantity of each into the molten steel.
Part of the carbon of this spiegeleisen unites with the oxygen occluded in the molten iron to form carbonic oxide, and again a bright flame, greenish with manganese, escapes from the converter.
Another way of introducing the carbon is Darby's process of throwing large paper bags filled with anthracite, coke or gas-carbon into the casting ladle as the molten steel is pouring into it.
The two great essential discoveries were first that the rapid passage of air through molten cast iron raised its temperature above the melting point of low-carbon steel, or as it was then called " malleable iron," and second that this low-carbon steel, which Bessemer was the first to make in important quantities, was in fact an extraordinarily valuable substance when made under proper conditions.
In order that the phosphoric acid may be the more fully liberated by the humic acid, &c., of the earth, a little silicious sand is mixed with the still molten slag after it has been poured off from the molten steel.
On account of this difficulty the moulds formerly stood, not on cars, but directly on the floor of a casting pit while receiving the molten steel.
For making castings, especially those which are so thin and intricate that, in order that the molten steel may remain molten long enough to run into the thin parts of the mould, it must be heated initially very far above its melting-point, the Bessemer process has a very great advantage in that it can develop a much higher temperature than is attainable in either of its competitors, the crucible and the openhearth processes.
The open-hearth process consists in making molten steel out of pig or cast iron and " scrap," i.e.
The charge may be melted down on the " open hearth " itself, or, as in the more advanced practice, the pig iron may be brought in the molten state from the blast furnace in which it is made.
Then the furnaceman, controlling the decarburization and purification of the molten charge by his examination of test ingots taken from time to time, gradually oxidizes and so removes the foreign elements, and thus brings the metal simultaneously to approximately the composition needed and to a temperature far enough above its present meltingpoint to permit of its being cast into ingots or other castings.
He then pours or taps the molten charge from the furnace into a large clay-lined casting ladle, giving it the final additions of manganese, usually with carbon and often with silicon, needed to give it exactly the desired composition.
makes the charge more and more infusible; and this progressive rise of the melting-point of the charge must not be allowed to outrun the actual rise of temperature, or in other words the charge must always be kept molten, because once solidified it is very hard to remelt.
Thus the necessary slowness of the heating up of the molten charge would compel us to make the removal of the carbon slow, even if this slowness were not already forced on us by the danger of having the charge froth so much as to run out of the furnace.
Bertrand and Thiel oxidize the carbon of molten cast iron by pouring it into a bath of molten iron which has first been oxygenated, i.e.
The oxygenated metal is prepared by melting cast iron diluted with as much scrap steel as is available, and oxidizing it with the flame and with iron ore as it lies in a thin molten layer, on the hearth of a large open-hearth furnace; the thinness of the layer hastens the oxidation, and the large size of the furnace permits considerable frothing.
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.
After the charge has been fully melted, it is held in the molten state from 30 to 60 minutes.
It is true that Reaumur in 1722 described his method of making molten steel in crucibles, and that the Hindus have for centuries done this on a small scale, though they let the molten steel resolidify in the crucible.
In the Bell-Krupp or "pig-washing" process, invented independently by the famous British iron-master, Sir Lowthian Bell, and Krupp of Essen, advantage is taken of the fact that, at a relatively low temperature, probably a little above 1200° C., the phosphorus and silicon of molten cast iron are quickly oxidized and removed by contact with molten iron oxide, though carbon is thus oxidized but slowly.
By rapidly stirring molten iron oxide into molten pig iron in a furnace shaped like a saucer, slightly inclined and turning around its axis, at a temperature but little above the melting-point of the metal itself, the phosphorus and silicon are removed rapidly, without removing much of the carbon, and by this means an extremely pure cast iron is made.
23) is practically a large closed crucible, Abca, with two carbon electrodes, E and F, " in series " with the bath, H, of molten steel.
A pair of electric arcs play between these electrodes and the molten steel, passing through the layer of slag, G, and generating much heat.
The lining of the crucible may be of either magnesite (MgO) or chromite (FeO Cr203) The whole furnace, electrodes and all, rotates about the line KL for the purpose of pouring out the molten FIG.
24), which contains the molten charge.
The molten metal in the Kjellin trough forms the " secondary " circuit.
The shape which the molten metal under treatment has in the Kjellin furnace, a thin ring of large diameter, is evidently bad, inconvenient for manipulation and with excessive heat-radiating surface.
the molten metal lies chiefly in a large compact mass A, heated at three places on its periphery by the current induced in it there by means of the three coils and cores CCC. The molten metal also extends round each of these three coils, in the narrow channels B.
When the Heroult furnace is used for completing the purification of molten steel begun in the Bessemer or open-hearth process, and this is its most appropriate use, the process carried out in it may be divided into two stages, first dephosphorization, and second deoxidation and desulphurization.
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.
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 comes the deoxidizing and desulphurizing stage, of which the first step is to throw some strongly deoxidizing substance, such as coke or ferro-silicon, upon the molten metal, in order to remove thus the chief part of the oxygen which it has taken up during the oxidation of the phosphorus in the preceding stage.
Coke now charged into this slag first deoxidizes any iron oxide contained in either slag or metal, and next deoxidizes part of the lime of the slag and thus forms calcium, which, uniting with the sulphur present in the molten metal, forms calcium sulphide, CaO+FeS-}-C=CaS+Fe+CO.
When the desulphurization is sufficiently complete, the sulphurbearing slag is removed, the final additions needed to give the metal exactly the composition aimed at are made, and the molten steel is tapped out of the furnace into its moulds.
to melt down very pure iron for the manufacture of the best kinds of steel, such as fine tool and spring steel, and to bring the molten metal simultaneously to the exact composition and temperature at which it should be cast into its moulds.
This furnace may be used also for purifying the molten metal, but it is not so well suited as the arc furnaces for dephosphorizing.
The Roechling-Rodenhauser furnace is unfitted, by the vulnerability of its interior walls, for receiving charges of cold metal to be melted down, but it is used to good advantage for purifying molten basic Bessemer steel sufficiently to fit it for use in the form of railway rails.
We are now in a position to understand why electricity should be used as a source of heat in making molten steel.
Electric furnaces are at an advantage over others as regards the removal of sulphur and of iron oxide from the molten steel, because their atmosphere is free from the sulphur always present in the flame of coal-fired furnaces, and almost free from oxygen, because this element is quickly absorbed by the carbon and silicon of the steel, and in the case of arc furnaces by the carbon of the electrodes themselves, and is replaced only very slowly by leakage, whereas through the Bessemer converter and the open-hearth furnace a torrent of air is always rushing.
why the molten metal can be freed from mechanically suspended slag more perfectly in them than in the Bessemer converter or the open-hearth furnace.
In short the electric furnaces can be used to improve the molten product of the Bessemer converter and open-hearth furnace, essentially because their atmosphere is free from sulphur and oxygen, and because they can therefore remove sulphur, iron oxide and mechanically suspended slag, more thoroughly than is possible in these older furnaces.
- When Bessemer discovered that by simply blowing air through molten cast iron rapidly he could make low-carbon steel, which is essentially wrought iron greatly improved by being freed from its essential defect, its necessarily weakening and embrittling slag, the very expensive and exhausting puddling process seemed doomed, unable to survive the time when men should have familiarized themselves with the use of Bessemer steel, and should have developed the evident possibilities of cheapness of the Bessemer process.
the manufacture of castings of cast iron, consists essentially in pouring the molten cast iron into, moulds, and, as preparatory steps, melting the cast iron itself and preparing the moulds.
In a very few places the molten cast iron as it issues from the blast furnace is cast directly in these moulds, but in general it is allowed to solidify in pigs, and then remelted either in cupola furnaces or in air furnaces.
The iron is then held molten till it has grown hot enough for casting and till enough of its carbon has been burnt away to leave just the carbon-content desired, and it is then tapped out and poured into the moulds.
- Cast iron naturally has a high carbon-content, usually between 3 and 4%, because while molten it absorbs carbon greedily from the coke with which it is in contact in the iron blast furnace in which it is made, and in the cupola furnace in which it is remelted for making most castings.
- Sulphur has the specific harmful effects of shifting the carbon from the state of graphite to that of cementite, and thus of making the metal hard and brittle; of making it thick and sluggish when molten, so that it does not run freely in the moulds; and of making it red short, i.e.
brittle at a red heat, so that it is very liable to be torn by the aeolotachic contraction in cooling from the molten state; and it has no good effects to offset these.
- In an early period of the solidification of a molten steel ingot cast in a cold iron mould we may distinguish three parts: (1) the outer layers, i.e.
the remainder of the solid metal; and (3) the molten lake, i.e.
the part which still is molten.
Because the outer and inner layers are integrally united, this excess of contraction of the inner layers makes them draw outward towards and against the outer layers, and because of their thus drawing outward the molten lake within no longer suffices to fill completely the central space, so that its upper surface begins to sink.
This ebb continues, and, combined with the progressive narrowing of the molten lake as more and more of it solidifies and joins the shore layers, gives rise to the pipe, a cavity like an inverted pear, as shown at C in fig.
Because this pipe is due to the difference in the rates of contraction of interior and exterior, it may be lessened by retarding the cooling of the mass as a whole, and it may be prevented from stretching down deep by retarding the solidification of the upper part of the ingot, as, for instance, by preheating the top of the mould, or by covering the ingot with a mass of burning fuel or of molten slag.
This keeps the upper part of the mass molten, so that it continues to flow down and feed the pipe during the early part of its formation in the lower and quickercooling part of the ingot.
when molten, i.e.
Because the volume of the pipe represents the excess of the contraction of the inner walls and the molten lake jointly over that of the outer walls, between the time when the lake begins to ebb and the time when even the axial metal is too firm to be drawn further open by this contraction, the space occupied by blowholes must, by compensating for part of this excess, lessen the size of the pipe, so that the more FIG.
Blowholes may be lessened or even wholly prevented by adding to the molten metal shortly before it solidifies either silicon or aluminium, or both; even as little as 0.002% of aluminium is usually sufficient.
These additions seem to act in part by deoxidizing the minute quantity of iron oxide and carbonic oxide present, in part by increasing the solvent power of the metal for gas, so that even after freezing it can retain in solution the gas which it had dissolved when molten.
- The solidification of an ingot of steel takes place gradually from without inwards, and each layer in solidifying tends to expel into the still molten interior the impurities which it contains, especially the carbon, phosphorus, and sulphur, which by this process are in part concentrated or segregated in the last-freezing part of the ingot.
There are two distinct ways of making the steel objects actually used in the arts, such as rails, gear wheels, guns, beams, &c., out of the molten steel made by the Bessemer, open hearth, or crucible process, or in an electric furnace.
aeolotachically; and this aeolotachic contraction is very likely to concentrate severe stress on the slowest cooling parts at the time when they are passing from the molten to the solid state, when the steel is mushy, with neither the fluidity of a liquid nor the strength and ductility of a solid, and thus to tear it apart.
- When the outer crust of a large ingot in which a lot of molten steel has been cast has so far cooled that it can be moved without breaking, the temperature of the interior is still far above that suitable for rolling or hammering - so far above that the surplus heat of the interior would more than suffice to reheat the now cool crust to the rolling temperature, if we could only arrest or even greatly retard the further escape of heat from that crust.
This seems to be the case with molten sulphur, which, when heated, becomes dark-coloured and plastic; and also in the case of metals, which obtain or lose magnetic properties without loss of continuous structure.
The system of coinage is also curious: 105 English rupees are melted down, and the alloy extracted, leaving 100 rupees' worth of silver; 295 more English rupees are then melted, and the molten metal mixed with the 100 rupees silver; and out of this 808 Kandahari rupees are coined.
It prohibits the making of molten images (v.
10, II), and omits the prohibition of molten images (xx.
At the instigation of the people Aaron makes a molten calf out of the golden ornaments brought from Egypt; Moses and Joshua, on their return to the camp, find the people holding festival in honour of the occasion; Moses in his anger breaks the tables of the covenant which he is carrying: he then demolishes the golden calf, and administers a severe rebuke to Aaron.
They prohibit (1) the worship of other gods, (2) the making of molten images; they ordain (3) the observance of the feast of unleavened bread, (4) the feast of weeks, (5) the feast of ingathering at the end of the year, and (6) the seventhday rest; to Yahweh belong (7) the firstlings, and (8) the firstfruits of the land; they forbid also (9) the offering of the blood of sacrifice with leaven, (io) the leaving-over of the fat of a feast until the morning, and (r1) the seething of a kid in its mother's milk.
Thallic oxide, T1203, is obtained as a dark reddish powder, insoluble in water and alkalis, by plunging molten thallium into oxygen, or by electrolysing water, using a thallium anode.
It also dissolves quite readily in some molten metals, especially silver.
Its eruptions are not on a grand scale, but small outbursts of lava and explosions of steam occur at frequent intervals, and at longer intervals more violent explosions in which the molten rock is thrown 2000 ft.
Casting also is complicated by the shrinkage which occurs in cooling down from the molten state, and in some alloys by the formation of eutectics, and the liquation of some constituents.
Before finishing, the molten mass must be kept at a quiet FIG.
CREDITON, a market town in the South Molten parliamentary division of Devonshire, England, 8 m.
Having crossed the Euphrates he hastened to make himself master of Parthia; but he was defeated at Carrhae (53 B.C.) and taken prisoner by Surenas, the Parthian general, who put him to death by pouring molten gold down his throat.
The molten metal is sea-green in colour, and at higher temperatures (in the electric arc) it vaporizes and burns with a green flame.
Molten copper absorbs carbon monoxide, hydrogen and sulphur dioxide; it also appears to decompose hydrocarbons (methane, ethane), absorbing the hydrogen and the carbon separating out.
The gases are also expelled from the molten metal by lead, carbon dioxide, or water vapour.
This is effected by stirring the molten metal with a pole of green wood (" poling "); the products which arise from the combustion and distillation of the wood reduce the oxide to metal, and if the operation be properly conducted " tough-pitch " copper, soft, malleable and exhibiting a lustrous silky fracture, is obtained.
The surface of the molten metal is protected from oxidation by a layer of anthracite or charcoal.
Rosette " copper is obtained as thin plates of a characteristic dark-red colour, by pouring water upon the surface of the molten metal, and removing the crust formed.
The matte also, in all economically planned works, is conveyed, still molten, by electric cranes from the furnace to the converters.
The trientoxide, Cu 3 0, is obtained when cupric oxide is heated to 1500 0 -2000° C. It forms yellowish-red crystals, which scratch glass, and are unaffected by all acids except hydrofluoric; it also dissolves in molten potash.
When molten, silver occludes the oxygen of the atmosphere, absorbing 20 times its own volume of the gas; the oxygen, however, is not permanently retained, for on cooling it is expelled with great violence; this phenomenon is known as the "spitting" of silver.
It is prevented by preserving the molten metal from contact with air by covering the surface with non-oxidizing agents, or by traces of copper, bismuth or zinc.
Most interesting among these are the Henry Mountains, formed by the intrusion of molten igneous rock between the layers of sediments, causing the overlying layers to arch up into dome mountains.
The crude phosphorus is purified by melting under water and then filtering through animal black and afterwards through chamois leather, or by treating it, when molten, with chromic acid or a mixture of potassium bichromate and sulphuric acid; this causes the impurities to rise to the surface as a scum which can be skimmed off.
It is usually sent on the market in the form of sticks, which were at one time prepared by sucking the molten material up glass tubes; but the dangers to the workmen and other disadvantages of this method have led to its replacement by a continuous process, in which the phosphorus leaves the melting-pot for a pipe surrounded by water, in which it solidifies and can be removed as a continuous rod.
Molten phosphorus is a viscid, oily, highly refractive liquid, which may be supercooled to 32° before solidification.
- Ferrous sulphide, FeS, results from the direct union of its elements, best by stirring molten sulphur with a white-hot iron rod, when the sulphide drops to the bottom of the crucible.
These he carried on for two years before he evolved the essential idea of his proc.:ss, which is the decarbonization of cast iron by forcing a blast of air through the mass of metal when in the molten condition.
In 1843 a German bee-keeper, Krechner by name, conceived the idea of first dipping fine linen into molten wax, then pressing the sheets so made between rollers, and thus forming a waxen midrib on which the bees would build their combs.
by repeated dippings of damped boards in molten wax (kept in liquid condition in tanks immersed in hot water) until the sheet was of suitable thickness for the purpose.
Less tender plants can be treated by the analogous method of maceration, which consists in extracting the odoriferous substances by macerating the flowers in hot oil or molten fat.
Such parts as may be subjected to extreme heat and the fretting action of molten material, as the tuyere and slag breasts of blast furnaces, and the fire bridges and bed plates of reverberatory furnaces, are often made in cast iron with double walls, a current of water or air being kept circulating through the intermediate space.
Darkyn was standing beside a molten tear in the earth, flanked by seven demons that stood one and a half times the size of Gabriel, the largest man Wynn knew.
She stepped closer to him as she had in their dream, gazing up into his molten silver eyes. He'd gone to Hell for Hannah and confronted Death for her. He'd killed demons to protect her and defied his family to find â€“ and keep â€“ her.
If I squeeze it a jet of molten bramley apple is going to squirt out.
Both carbon and alloy steels are produced in electric arc furnaces and scrap rather than molten metal is used as the base material.
The skilled Egyptian glass blower takes a small bubble of molten glass.
bludgeons heavily loaded with molten lead.
Then the furnaces fire up to prepare the molten bronze - a mix with 22 or 23% tin is used.
Titanium Titanium metal made by electrolysis of titanium dioxide in molten calcium chloride.
The extraction of sodium from molten sodium chloride using the ' Down's Cell ' .
cobalt oxide to the molten glass.
The magnetic field of the Earth is generated in its molten iron core.
The local salt chemistry creates molten slags which, in turn, cause enhanced scale growth and localized corrosion.
Its paint is so creamy it's like molten wax.
crucible furnace A smelting furnace incorporating a ceramic bowl in which the molten product is caught or retained.
electric furnaced alloy steels are produced in electric arc furnaces and scrap rather than molten metal is used as the base material.
Metal transfer The transfer of metal across the arc from a consumable electrode to the molten pool.
The electrolytic extraction of sodium Sodium, like many reactive metals, can be extracted by electrolysis of its molten chloride.
electrolysis of a molten metallic fluoride (perhaps potassium fluoride KF?
encaustic painting - creative artwork with molten wax paint colors.
To ensure that the composition of the alloy is correct, samples of the molten metal are routinely checked by X-ray fluorescence spectrometry.
Fluorine for the manufacturing process was generated on-site by electrolysis of a molten metallic fluoride (perhaps potassium fluoride KF?
fluorine for the manufacturing process was generated on-site by electrolysis of a molten metallic fluoride (perhaps potassium fluoride KF?
I couldn't resist the hot chocolate fondant with its soft, dark, molten interior.
It's a very clever variant on the warm chocolate fondant with the molten choc oozing out of the sponge.
After the last molten flow came nothing but sulfurous fumes from a pressurized underworld.
Tea light holders made from molten recycled glass are our latest product offering.
greenstone belt - an elongated group of specific rocks derived from molten lava intruded into pre-existing rock or extruded onto surface.
Later Wendy cooked ham & peaches followed by pears in reluctant molten Mars Bar sauce.
Steel Most of the molten iron from a Blast Furnace is used to make one of a number of types of steel.
We decided these were formed by molten lava building up around trees, which burnt away.
The molten rock, called magma, has reached the surface of Mount Pinatubo.
The Japanese islands have been formed from the molten magma released by the melting Philippines Plate.
magnetic field of the earth is generated in its molten iron core.
Blessed, 8, from Zimbabwe, a country in southern Africa, knows all about molten metal.
Pouring a molten metal into a metal mold with enhanced cooling produces finer grains.
molten lava building up around trees, which burnt away.
molten magma released by the melting Philippines Plate.
molten solder over to the joint!
molten slag to escape.
molten sodium chloride using the ' Down's Cell ' .
molten metal falling into water.
There is evidence for volcanic type activity suggesting a once molten core.
Hot pewter poured into a cool mold solidifies around the contact with the mold, allowing the still molten core to be poured out.
Beneath the plates is a layer of partly molten rock.
First the solder on the pads melts and wets the pad and the ball surface; then the whole ball becomes molten.
LAVA FLOWS These are flows of extremely hot molten rocks extruded by the volcano.
Consider for example, the electrolysis of the molten salt, NaCl.
Pig iron is refined in a converter and then poured into molten iron silicate slag.
A hole is dug into the ground making a channel to allow molten slag to escape.
Room temperature ionic liquids are liquids which consist solely of ions, e.g. molten sodium chloride.
It employs a continuously generated wave of molten solder to form the joints.
We also encouraged the molten glue to penetrate by bouncing a plastic car window squeegee on the surface like a drain plunger.
sulphurng molten sulfur in either air or pure oxygen leads to a reaction, which produces a pale blue colored flame.
thermoplastics in the molten state (under development ).
It is most commonly applied by dipping the item into a large tank of molten zinc.
Molten anhydrous zinc chloride gives zinc (+) and chlorine (- ), equations 1 and 2.
The resulting surface is usually duller and less lustrous than that obtained by the use of molten zinc. Another method of forming a coating of zinc, known as "sherardizing," was invented by Sherard CowperColes, who found that metals embedded in zinc dust (a product obtained in zinc manufacture and consisting of metallic zinc mixed with a certain amount of zinc oxide) and heated to temperatures well below the melting point of zinc, become coated with a layer of that metal.
It forms grey coloured octahedra of specific gravity 5.49 6 at 20Ã‚° C., melting at 900Ã‚° C.; it burns at a red heat, is insoluble in hydrochloric acid, but dissolves in aqua regia, and is also soluble in molten alkalis.
The second method is analogous to the calcarone method of liquation: the ore is placed in a limekiln-like furnace over a mass of kindled fuel to start a partial combustion of the mineral, and the process is so regulated that, by the heat generated, the unburnt part is decomposed with elimination of sulphur, which collects in the molten state on an inverted roof-shaped sole below the furnace and is thence conducted into a cistern.
20, 451, 757) regards molten sulphur as a mixture of two isomers SA and Sµ in dynamic equilibrium, SA being light in colour and mobile, and S, dark and viscous.
The metal is dimorphous: by cooling molten tin at ordinary air temperature tetragonal crystals are obtained, while by cooling at a temperature just below the melting point rhombic forms are produced, When exposed for a sufficient time to very low temperatures (to - 39Ã‚° C. for 14 hours), tin becomes so brittle that it falls into a grey powder, termed the grey modification, under a pestle; it indeed sometimes crumbles into powder spontaneously.
Faraday independently recognized the necessity for mechanical agitation of the molten glass in order to ensure homogeneity, and to facilitate his manipulations he worked with dense lead borate glasses which are very fusible, but have proved too unstable for ordinary optical purposes.
The canes adhere to the molten glass, and the mass is first twisted and then drawn out into fine cane, which contains white threads arranged in endless spirals.
The gatherer dips the butt of the pipe into the molten " metal " and withdraws upon it a small ball of viscous glass, which he allows to cool in the air while constantly rotating it so as to keep the mass as nearly spherical in shape as he can.
The bottle maker heats the fractured neck of the bottle, binds a band of molten glass round the end of it and simultaneously shapes the inside and the outside of the neck by using the tool shown in fig.
In the case of the machine patented by Michael Owens of Toledo, U.S.A., for making tumblers, lamp-chimneys, and other goods of similar character, the manual operations required are (r) gathering the molten glass at the end of a blowing iron; (2) placing the blowing iron with the glass attached to it in the machine; (3) removing the blowing iron with the blown vessel attached.
The glass for pressed ware must be colourless, and, when molten, must be sufficiently fluid to adapt itself readily to the intricacies of the moulds, which are often exceedingly complex.
Most metals when molten are capable of dissolving at least small proportions of carbon, which, in general, leads to a deterioration in metallicity, except in the case of iron, which by the addition of small percentages of carbon gains in elasticity and tensile strength with little loss of plasticity (see Iron).
It fuses at 415Ã‚° C. and under ordinary atmospheric pressure boils at 1040Ã‚° C. Its vapour density shows that it is monatomic. The molten metal on cooling deposits crystals belonging to the hexagonal system, and freezes into a compact crystalline solid, which may be brittle or ductile according to circumstances.
232Ã‚° Sn A Sir William Chandler Roberts-Austen has shown that in the case of molten alloys the conduction of electricity is apparently metallic, no transfer of matter attending the passage of the current.
Cowper Coles has suggested aluminium cathodes; Andreoli has recommended cathodes of iron and anodes of lead coated with lead peroxide, the gold being removed from the iron cathodes by a brief immersion in molten lead; in the Pelatan-Cerici process the gold is amalgamated at a mercury cathode (see also below).
Vapour baths of iron are used in connexion with boiling anthracene (335Ã‚°), anthraquinone (368Ã‚°),sulphur(444Ã‚°),phosphoruspentasulphide(518Ã‚°); molten lead may also be used.
It has been found, however, that molten cryolite and the analogous double fluoride represented by the formula Al 2 F 6.2NaF are very efficient solvents of alumina, and that these solutions can be easily electrolysed at about 800Ã‚° C. by means of a current that completely decomposes the oxide but leaves the haloid salts unaffected.
The molten metal has a specific gravity of 2 Ã¯¿½ S4, that of molten cryolite saturated with alumina is 2.3 5, and that of the fluoride Al 2 F 6 2NaF saturated with alumina 1.97.
In the Bessemer or " pneumatic" process, which indeed might be called the " fuel-less " process, molten pig iron is converted into steel by having its carbon, silicon and manganese, and often its phosphorus and sulphur, oxidized and thus removed by air forced through it in so many fine streams and hence so rapidly that the heat generated by the oxidation of these impurities suffices in and by itself, unaided by burning any other fuel, not only to keep the iron molten, but even to raise its temperature from a point initially but little above the melting point of cast iron, say 1150 to 1250Ã‚° C., to one well above the melting point of the resultant steel, say i soo C. The " Bessemer converter " or " vessel " (fig.
In the Bell-Krupp or "pig-washing" process, invented independently by the famous British iron-master, Sir Lowthian Bell, and Krupp of Essen, advantage is taken of the fact that, at a relatively low temperature, probably a little above 1200Ã‚° C., the phosphorus and silicon of molten cast iron are quickly oxidized and removed by contact with molten iron oxide, though carbon is thus oxidized but slowly.
The " tread " or circumferential part of the mould itself is made of iron, because this, by conducting the heat away from the casting rapidly, makes it cool quickly, and thus causes most of the carbon here to form cementite, and thus in turn makes the tread of the wheel intensely hard; while those parts of the mould which come in contact with the central parts of the wheel are made of sand, which conducts the heat away from the molten metal so slowly that it solidifies slowly, with the result that most of its carbon forms graphite, and here the metal is soft and shock-resisting.
sq., has been explained by the theory that the relative quiet due to the gentleness of the convection currents in a slowly cooling mass favours the formation of far outshooting pine-tree crystals, and that the tangled branches of these crystals landlock much of the littoral molten mother metal, and thus mechanically impede that centreward diffusion and convection of the impurities which is the essence of segregation.
Moissan has produced the diamond artificially, by allowing dissolved carbon to crystallize out at a high temperature and pressure from molten iron, coupled with the occurrence in meteoric iron, has led Sir William Crookes and others to conclude that the mineral may have been derived from deep-seated iron containing carbon in solution (see the article GEM, Artificial).
(4) The Acker-Douglas process electrolyses sodium chloride in the molten state, employing a cathode consisting of molten lead.
" Bean-shot " copper is obtained by throwing the molten metal into hot water; if cold water be used, " feathered-shot " copper is formed.
The trientoxide, Cu 3 0, is obtained when cupric oxide is heated to 1500 0 -2000Ã‚° C. It forms yellowish-red crystals, which scratch glass, and are unaffected by all acids except hydrofluoric; it also dissolves in molten potash.
Molten phosphorus is a viscid, oily, highly refractive liquid, which may be supercooled to 32Ã‚° before solidification.
Burning molten sulfur in either air or pure oxygen leads to a reaction, which produces a pale blue colored flame.
ISO/DIS 16790: Plastics - Determination of drawing characteristics of thermoplastics in the molten state (under development).
Molten anhydrous zinc chloride gives zinc (+) and chlorine (-), equations 1 and 2.
Amorphous panels are made of a thin film of molten silicon spread across plates of stainless steel.
Candy Mess: If you are unfamiliar with recipes or techniques, you may end up with a molten mess instead of the candy in the recipe.
This recycling method is very labor-intensive as the molten glass with color already added, is poured into a pancake on a metal table and then pressed with a cookie cutter-like form to create the squares.
Once it becomes molten, the craftsmen hand-ladle the mixture into iron molds.
The technique of hand forming glass beads is known as lamp or flame working and rods of glass are heated in the flame of a torch until molten and then formed into shapes.
The rich blues and greens of glass give the impression of the sea and the fluid shapes formed by the molten glass create wonderful and unusual shapes.
This glistening G-string features a contoured pouch that actually looks like molten metal!
Although people should also remember that while there is no naked flame, a warmer does heat up wax until it is molten and as such this should be carefully situated so that it can not be knocked or spilled.
Pyramid Games features games like "Professor Fizzwizzle and the Molten Mystery", a Shareware game, but you can own a registered version for a fee as well.
They are made by heating the glass until it becomes a long string of molten glass and then wrapping it around a slim steel rod.
Blown-glass beads: A tube is covered with molten glass and the bead maker blows into the tube and turns it over a heat source to make the bead the required size and shape.
Wound glass beads: A metal wire is used to wind the molten glass around.
Heat the coated end of your wire just until it changes color, then heat a glass rod until it makes a molten ball of glass.
Molten lava cakes use a smooth, rich chocolate filling served warm.
Type of Cake: While classic sponge cakes are popular, cheesecakes, cookie cakes, and molten chocolate cakes are other sweet variations.
The word usage examples above have been gathered from various sources to reflect current and historial usage. They do not represent the opinions of YourDictionary.com.