THE PENNY CYCLOPÆDIA OF THE SOCIETY FOR THE DIFFUSION OF USEFUL KNOWLEDGE. VOLUME XXIII. STEARIC ACID--TAGUS. LONDON: CHARLES KNIGHT AND Co., 22, LUDGATE STREET. MDCCCXLII. Price Seven Shillings and Sixpence, bound in cloth. COMMITTEE. Chairman-The Right Hon. LORD BROUGHAM, F.R.S., Member of the National Institute of France. William Allen, Esq., F.R. and R.A.S. Captain Beaufort, R.N., F. R. and R.A.S. George Burrows, M.D. Peter Stafford Carey, Esq., A.M. John Conolly, M.D. William Coulson, Esq. The Right Rev. the Bishop of St. David's, D.D. J. F. Davis, Esq., F.R.S. Sir Henry De la Beche, F.R.S. The Right Hon. Lord Denman, Samuel Duckworth, Esq. The Right Rev. the Bishop of Durham, D.D. T. F. Ellis, Esq., A.M., F.R.A.S. John Elliotson, M.D.. F.R.S. The Right Hon. George Evans. John Forbes, M.D. and F.R.S. Sir I. L. Goldsmid, Bart., F.R. and R.A.S. Treasurer-JOHN WOOD, Esq. Francis Henry Glodsmid, Esq. B. Gompertz, Esq., F.R. and R.A.S. J. T. Graves, Esq., A.M., F.R.S. G. B. Greenough. Esq., F.R. and L.S. Sir Edmund Head, Bart., A.M. M. D. Hill, Esq, Q.C. Rowland Hill, Esq., P.R.A.S. Right Hon. Sir J. C. Hobhouse, Bart., M.P. David Jardine, Esq., A.M. Henry B. Ker, Esq. Thomas Hewitt Key, Esq.. A.M. James Loch, Esq., M.P., F.G.S. Mr. Sergeant Manning. R. I. Murchison, Esq.. F.R.S., F.G.S. W. S. O'Brien, Esq., M.P. Richard Quain. Esq. P. M. Roget, M.D. Sec. R.S., F.R.A.S. Sir Martin Archer Shee, P. R.A., F.R.S. Sir George T. Staunton, Bart., M.P. A. T. Thomson, M.D. F.L.S. Thomas Vardon, Esq. Jacob Waley, Esq.. B.A. Jas. Walker, Esq., F.R.S., Pr. Inɛt., Civ. Eng. H. Waymouth, Esq. Thos. Webster, Esq., A.M. Right Hon. Lord Wrottesley, A.M., F.R.A.S. J. A. Yates, Esq. Bridport-James Williams, Esq. J. B. Estlin, Esq., F.L..S., Secretary. C. H. Cameron, Esq. Cambridge-Rev. Leonard Jenyne, M.A., F. L.S. Rev. John Lodge, M.A. Rev. Prot. Sedgwick, M.A., F.R.S. & G.S. Carlisle-Thomas Barnes, M.D., F.R.S.E. William Roberts, Esq. Chester-Henry Potts, Esq. Cockermouth-Rev. J. Whitridge. Corfu John Crawford, Esq. Coventry-C. Bray, Esq Denbigh-Thomas Evans, Esq. Derby-Joseph Strutt, Esq. Edward Strutt, Esq.. M.P. Devonport and Stonehouse-John Cole, Esq. John Norman, Esq. Lt. Col. C. Hamilton Smith, F.R.S. LOCAL COMMITTEES, Etruria-Josiah Wedgwood, Esq. John Milford, Esq. (Coaver.) Alexander McGrigor, Esq Hitcham, Suffolk Rev. Professor Henslow, Henry Browne. Esq. Liverpool Loc. As.-J. Mulleneuz, Esq. Manchester Loc. As.-G. W. Wood, Esq., Sir Benjamin Heywood, Bt., Treasurer. T. N. Winstanley, Esq., Hon. Sec. T. Sopwith, Esq., F.G.S. Newport, Isle of Wight-Ab. Clarke, Esq. R. G. Kirkpatrick, Esq. Ripon Rev H.P. Hamilton, M.A., F.R.S.,G.S. Ruthin-Rev. the Warden of Humphreys Jones, Esq Ryde, I. of Wight-Sir Rd. Simeon, Bt. Sheffeld- H. Abraham, Esq. Shepton Mallet-G. F. Burroughs, Esq. South Petherton-John Nicholetts, Esq. Henry Coppock, Esq., Secretary. John Rundle, Esq., M.P. THOMAS COATES, Esq., Secretary, No. 59, Lincoln's lan Fields. London: Printed by VILLIAM CLOWES and SONS, Stamford Street. THE PENNY CYCLOPÆDIA OF THE SOCIETY FOR THE DIFFUSION OF USEFUL KNOWLEDGE. STE STEARIC ACID. This substance is procured from stearin [STEARIN], which is a compound of stearic acid and a peculiar sweet substance called glycerin, which is treated of under the head of SOAP. When stearin is saponified by potash, stearate of potash is procured; and when warm dilute hydrochloric acid is added to the solution, the stearate is decomposed, chloride of potassium remains in solution, and the stearic acid is precipitated. The properties of this acid are, that it has the form of brilliant white scaly crystals; it is inodorous, tasteless, insoluble in water, soluble in its own weight of æther and in hot alcohol, and the solution reddens litmus-paper; but its acid action is feeble, for it expels carbonic acid from the alkaline carbonates only at a boiling heat. It melts at about 158° Fahrenheit, and on cooling it forms a crystalline mass; it is volatile, and may be distilled unaltered in close vessels. In the air it burns like wax. Its composition is somewhat differently stated by authors, but no one statement differs much from In the state of crystals it contains two equivalents of water 18, or nearly 34 per cent. It forms compounds with the alkalis, earths, and metallic oxides, which are called stearates. Stearate of Ammonia.-Stearic acid absorbs ammoniacal gas; the resulting compound is white, inodorous, and has an alkaline taste. It is dissolved by boiling water, and the solution, on cooling, deposits pearly crystals of stearate of ammonia. Di-stearate of Potash is formed by boiling equal weights of the acid and alkali dissolved in five times their weight of water. It forms a white granular compound, which is opaque, and may be purified by solution in boiling alcohol; as the solution cools, the salt separates in white brilliant scales. This compound may also be procured by treating potash soap with alcohol. Di-stearate of Soda and stearate of soda may be obtained by processes similar to those described for the stearates of potash; they are less soluble than the salts of potash, and enter into the composition of hard soaps. Stearate of Lime, Stearate of Barytes, and Stearate of Lead, are all white insoluble powders, and are not applied to any useful purpose. Stearic Acid, besides its use in the manufacture of soap, is now very largely employed in the making of candles. STEARIN (from Greap, fat) is the harder portion of animal fats; olein, or elain, being the softer one. To obtain stearin in a pure state, mutton-suet is to be melted with ten times its weight of æther in a water bath; as the solution cools, crystals of stearin are deposited, which, after washing with cold æther, are to be strongly pressed. The properties of stearin are, that it has a pearly lustre, is soft to the touch, but not greasy; it melts at about 140° to 145° Fahrenheit; and, on cooling, solidifies into a mass, like wax, which is not crystalline in its texture, and is reducible to powder. Stearin is insoluble in water, but is dissolved both by hot alcohol and æther, from which it most entirely separates on cooling; it possesses weak acid properties, and may be combined with potash; it is the chief and most important ingredient of the harder kinds of fat, and the harder they are the more they contain. Stearin is separable into two different principles, namely stearic acid and glycerin, as has already been noticed in the preceding article; it appears to be a bi-stearate of glycerin, consisting of Two equivalents of stearic acid 1028 83 18 Six equivalents of carbon Seven equivalents of hydrogen Five equivalents of oxygen 36 7 40 STEARON is obtained by the partial decomposition of stearic acid; when distilled with lime, carbonic acid is formed, and the stearon produced at the same time is volatilized, and condenses in the state of a volatile liquid: it appears to consist of Sixty-six equivalents of carbon 396 66 8 166791 So that it seems to be stearic acid deprived of two equivalents of carbonic acid. STEAROPTEN. Volatile oils, as obtained by distillation from plants, appear, like expressed oils, to consist of two substances; one solid, which has received the name of stearopten, and the other liquid, called elaopten: the former generally crystallizes when the oil has been long kept. Camphor is the most remarkable substance of the class of stearoptens. It is obtained by distillation with water, and in the plant is mixed with camphor-oil, from the gradual oxidation of which it appears to be produced. STEATITE, Soapstone, Speckstein, Talc-Steatite. This mineral, which is principally a hydrated silicate of magnesia, is met with massive in amorphous masses, which sometimes contain crystals of this substance of the form of quartz and calcareous spar, and which are probably pseudomorphous. Structure compact. Fracture uneven, splintery. Soft, and has a greasy feel. Colour yellowish, greenish, and greyish-white. Streak shining. Dull. Translucent on the edges. Specific gravity 2·604 to 2·632. Before the blowpipe it is infusible either alone or with additions. It occurs plentifully in Baireuth, Saxony; in Cornwall, in Scotland, and many other parts of the world. According to Klaproth it consists of STEEL. Iron possesses many qualities which render it applicable to innumerable purposes in the arts: but there are some uses for which it is not sufficiently hard, and this defect is supplied by converting it into steel. | estimated at 12,000 to 15,000 tons, of which at least 9000 come from Sweden. The usual operation in large steel-works is first to cut the bar-iron into certain lengths, leaving room in the vessels for the expansion of the iron, which amounts to The closed vessels in which the bars are heated are usually twelve feet in length, and divided into two pots or troughs, on the bottom of which the workman strews charcoal to the thickness of about an inch, and upou this he places on their flat side a layer of bars; then about three-fourths of an inch more of charcoal is added, and upon this he places another layer of bars, and so on till the troughs are filled; these are then covered with a ferruginous earth coming from the grinding-stones, called wheels warf, to the thickness of about eight inches. All the apertures of the furnace are then closed with loose bricks and plastered over with fire-clay. The fire is then lighted, and in four days and nights the furnace is at its full heat, at which it is kept for several days, according to the degree of hardness required. In order to be able to test the progress of the carbonization, a hole is left in one of the pots near the centre, and three or four bars are placed in the furnace in such a manner that the ends come through this opening, and after the sixth day one is pulled out. If the iron be then not sufficiently carbonized, the heating is continued from two to four days longer: a bar is drawn every two days, and when the iron is completely converted, the fire is heaped up with smallcoal, and the furnace is left to burn out, and it requires from this period fourteen days' time to cool sufficiently to allow a person to go in and discharge the steel. It is of the greatest importance that the pots or troughs be kept completely air-tight; the smallest crack will open when the furnace is hot, and admit the air: this of course frustrates the object of the operation, and any steel which has thus suffered is placed aside to be reconverted. It is of the greatest importance to give the iron the exact quantity of carbon required and no more. 1st. For couch-springs.-The iron must not be converted to the centre. At Eisenärzt in Styria the manufacture of steel has been carried on ever since the eighth century, and yet the exact nature of the operation is perhaps even now imperfectly 2nd. For common cutlery, single and sheer steel, and for understood. It is generally admitted that steel is an inti-purposes where steel has to be welded to itself or to iron, the mate compound of iron and charcoal, for soft iron contains a considerable portion of charcoal, and it is by no means clear that the quantity is increased in the process of steelmaking, and therefore we must conclude that some more intimate union is effected between them when iron is converted into steel. Whatever the theory may be, we shall now describe the mode in which the operation is conducted in this country, and principally at Sheffield. In the first place it is to be observed that hitherto Swedish and Russian bar-iron have been exclusively employed in the manufacture of the best steel; the preference given to this iron is decided, though from what cause it arises has not been satisfactorily made out. We may however remark that the foreign iron used is made from magnetic iron-ore with charcoal, while British iron is obtained mostly from the impure carbonate of iron, called argillaceous iron ore, or from hæmatite, which is a peroxide of iron, and both of these are reduced by employing coal or coke prepared from it. Bar-Steel is made,with few exceptions, from the Swedish and Russian iron, the bars of which are marked hoop 1 (1), gl (2), and double bullet (3); these, which are the best kinds, fetch from 31. to 357. per ton. Iron of lower quality is also used, such as (4), which is a Russian iron, and c and crown (5), d and crown (6), which are Swedish irons; these cost the importer about 207. per ton; whilst there is a medium quality at about 257. per ton, viz. w and crowns (7), b and W W WW. Y OOCC ND CDW B 5 6 7 8 1 2 3 crown (8); these also are Swedish. These steer irons are imported almost exclusively by English merchants residing in Hull; the limited quantity of the fine iron allowed to be produced from the mines of Danemora in Sweden accounts in some degree for the high price at which they are sold. The quantity of iron, of the various qualities stated, which is imported into this country for the manufacture of steel is A patent has lately been obtained by Mr. Charles Sanderson for making iron fit for conversion into steel; from some instruments made from the steel o produced, now in the possession of the writer of this article, he is inclined to think favourably of the process. conversion should be low, and gradually disseminated 4th. For files and all instruments where resistance or fine cutting-edges are required, the conversion should be hard, and the iron fully carbonized throughout the bar, and the fracture should present small facets. No definite rules can be laid down, nor can any distinct instructions be given to enable the uninitiated to judge of the temper or degree of hardness of a bar of steel; but by habit workmen soon acquire the means of distinguishing between the different degrees of hardness of two pieces of steel. This knowledge of the degree of temper is of great importance to the steel-maker, for though he is enabled to adapt the temper (hardness) of the steel to the wants of the manufacturer, a file, made from soft steel which would be valuable for welding purposes, would be useless in the arts, and a coach-spring made from steel hard enough to make a file could not be applied to its intended purpose. A converting furnace contains generally fifteen tons of iron; and there are some large enough to hold eighteen to twenty tons. The bar-steel, when discharged from the furnace, is partially covered with small raised portions of the metal; and from the resemblance of these to blisters, the steel is called blistered steel. It has been supposed that these blisters arise from the expansion of carbonic oxide gas, formed and confined during the process of cementation; this however is not the case, for they evidently arise from the unsoundness of the iron, which is not throughout perfectly welded. It has been found by the experiment of placing a bar of Swedish and one of Staffordshire bar-iron in the same furnace, that the former was much blistered, while the latter had scarcely any blisters larger than a pea. It must however be admitted that the cause of the blistering in one case, and its slight production in the other, are circumstances difficult of explanation. At one time it was common for the steel-maker to receive orders for steel well blistered. This arose from a mistaken idea regarding the perfection of the steel, it being supposed that the more it was blistered, the more it was carbonized, and consequently that its quality was indicated thereby; now however manufacturers are better informed, and steel so blistered is complained of. scribed as a steel-grey; it is susceptible of receiving a verv high polish, and this is greater as the grain is finer. The density of steel before hammering or hardening varies from Bar-steel as it comes from the converting furnace is used 773 to 784. Dr. Thomson found the density of good blisfor various purposes without refining; those parts which tered steel to be 7-823; by heating it to redness and sudden are free from flaws and blisters are broken out and ham- immersion in cold water, the density was reduced to 7·747: mered or rolled to the sizes required by the manufacturer a piece of soft cast-steel similarly treated was reduced in for files, edge-tools, table knives and forks, and coach-density from 7·8227 to 7.7532. It follows therefore that springs, and a great variety of common agricultural im- when steel is hardened its volume is increased. When steel plements. It is also manufactured into what is called is heated to redness and slowly cooled, it is scarcely harder single and double sheer steel; for this purpose the con- than iron; but by very rapid cooling it becomes hard, and verted bar is selected of equal degree of hardness, and so brittle as to be readily broken. The fracture of steel is broken into pieces of about two feet in length; these are usually fine grained; in ductility and malleability it is taken to the forge, heated to a full cherry red, and ham- much inferior to iron, but exceeds it greatly in elasticity and mered into bars two inches by three-quarters of an inch in sonorousness. It may be subjected to a full red heat, or thickness; six of these pieces are put together and kept 2786° Fahr., without melting, and is therefore less fusible firmly so by a hoop, which is fixed at the end of a handle, than cast-iron, but much more so than wrought-iron. Pieces thusof steel which have not been cast may be readily welded together or with iron; but after casting the operation is more difficult. Steel does not acquire magnetic polarity so readily as iron, but retains it much longer; by exposure however to a moderate degree of heat this power is lost. In order to give to steel the different degrees of hardness required for the various purposes to which it is applied, it is subjected to the process of what is called tempering. It has been mentioned that steel is hardened by heating and sudden cooling; and it is found that the higher the temperature to which it is raised, and the more sudden the cooling, the greater is the hardness: thus when immersed in mercury the hardness is greatest, on account of the good conducting power of the metal, and its consequent ready abstraction of heat. After this comes acidulated water, salt water, common water, and lastly oily or fatty bodies. It is found that, according to the degree to which steel is tempered, it assumes various colours, and formerly these colours served as guides to the workman; now however a thermometer, with a bath of mercury or of oil, is employed, and the operation is performed with a much greater degree of certainty. they are then placed in a hollow fire urged by a soft blast, and heated gradually up to a full welding heat, during which the workman covers the surface with clay beaten very fine; this runs over the surface, and to some extent prevents oxidation. When fully heated, they are placed under the hammer, carefully welded together and drawn into a bar of about two inches square at the same heat; the other end is then put into the fire and welded in the same way; this is termed single sheer steel. It is made double by nicking the bar in the middle and doubling it together, giving a second welding heat and drawing it out as before to a bar of about two inches square; it is then hammered, tilted, or rolled to the size required; by this process bur steel becomes more homogeneous, of a finer texture, and any instrument made of it will receive and retain a finer edge; the steel is also rendered much tougher, which is supposed to arise from the abstraction of a small portion of carbon, and the mechanical elongation of the fibre by these doublings, &c. Manufacture of Cast Steel.-The fabrication of cast steel is comparatively a recent invention. it was first made by Mr. Huntsman, at Attercliff, near Sheffield, in 1770, since which time the manufacture of it has very much increased, and it is daily superseding the use of bar or shear steel, on account of the equality of its temper, and the superior quality as well as beauty of the articles which are made of it. The process adopted is that of taking bar steel converted to a certain degree of hardness and breaking it into pieces of about a pound each; a crucible charged with these is placed in the melting-furnace, similar to that used by brass-founders. The cellar is usually arched, and the stacks are about 40 feet high; the furnaces are 20 inches long by 16 inches wide, and 3 feet deep. The most intense heat is kept up for two hours and a half or three hours, coke being used as fuel. When the furnace requires feeding, the workman takes the opportunity of lifting the lid of each crucible and judging how long the charge of each will be before it is completely melted: all the crucibles are usually ready about the same time; they are taken out of the furnace, and the liquid steel is poured into ingots of the shape and size required: the crucibles are immediately returned into the furnace; and when the contents of all have been poured into the moulds, the crucibles are again charged: they are used three times, and then rejected as useless. The ingots are taken to the forge-tilt or rolling-mill, and hammered into bars or rolled into sheets, as may be required. The celebrated wootz, or Indian steel, is cast-steel; but it is frequently so imperfect as to resemble cast-iron rather than cast-steel. It is however made of iron obtained, as the Swedish is, from the magnetic ore. Wootz is made by the natives from malleable iron, packed in small bits with wood in crucibles, which are then covered with some green leaves and clay: about two dozen of these crucibles are packed in one furnace; they are covered with fuel, and a blast given for about two hours and a half, which terminates the operation. When the crucibles are cold, they are broken, and small cakes of steel are obtained in the form in which it comes to England. Having stated the mode in which steel is prepared, we shall now give an account of its properties and composition, and a concise view of the theories of its formation. The properties of steel are, that it is of a lighter grey coiour than iron, and which is so characteristic as to be de Into this bath the articles to be tempered are put, with the bulb of the thermometer graduated up to the boilingpoint of mercury. The annexed are the tempering heats, colours, and uses of steel of different degrees of hard ness: 430° Fah., 450° 4700 490° 510° 530° 550° 560° 600° very faint yellow; for lancets. pale straw; razors and surgeons' instruments. full yellow; penknives. brown; scissors and chissels for cutting old iron. brown with purple spots; axes and plane-irons. purple; table-knives and large shears. bright blue; swords, watch-springs, truss-springs, and bell-springs. full blue; small fine saws, daggers, &c. full blue, verging on black; this is the softest of all the gradations, and the steel is fit only for hand and pit saws. The degree at which the respective colours and corresponding hardness are produced being thus known, the workman has only to heat the bath and its contents up to the required point. The degree of hardness attainable by steel depends upon the temperature to which it is raised, and the coldness or conducting power of the liquid into which it is immersed ; so that, as observed by Mr. Brande, if very cold water cannot be procured, the steel die or other article must be heated proportionably high; a dull red heat into water at 34°, a cherry-red into water at 50°, an orange heat into water at 80°, a dull white heat into water at 100°, produce nearly the same effects: a red heat and water at 45° is the most desirable for the hardening; and although by subsequent tempering the die may, if necessary, be brought down or softened, it is always safest to give it due hardness by the first operation. In some cases steel is sufficiently hardened before any change of colour is produced. Capt. Kater found that 212°, or the heat of boiling water, was the exact point at which the knife-edges attached to a pendulum were properly tempered. The colour produced on the surface of the steel is supposed to be derived from slight oxidizement; and it is stated in corroboration of this opinion, that when steel is heated and suffered to cool under mercury or oil, none of the colours appear; nor do they when it is heated in hydrogen or azotic gases: the cause however of the |