« 이전계속 »
colours, Indian-ink, &c." Such a paper. Sir, as this would be of coosiderable service to me, and I should b" obliged to any of your correspondents to give me the above demanded information. I am, Sir, Your obedient servant.
Mr. Editor,—I sometimes indulge in speculations on chemistry, but am not a practical chemist, and I may therefore commit gross errors in my dreams, in which, perhaps, some of your friends who are constantly in their laboratories, may set me right. I would ask—Is there not strong reason to suppose that the great antagonist principle,—if I may use this term for two substances that appear to have a great love for each other,—of oxygen is of a metallic nature? Is not hydrogen an antagonist principle of oxygen? Does not hydrogen exist in great plenty in the upper regions of the atmosphere? Is it not supposed that when there, it is sometimes inflamed by electricity, and forms, those fire-balls or meteors which areseenintheatmosphere? Andare not these fire-balls, or meteorolites, or whatever they may be called, when found in the earth, known to contain a particular metal, which is scarcely found any where else? Now, Sir, supposing all these questions answered in the affirmative, I would go on, and venture to ask, If it is not possible, as I believe has been conjectured by Sir Humphrey Davy, that hydrogen is of a metallic nature, and forms the basis, in some shape or other, of all the metals on the globe? If it is not, Sir, in short, what the alchymists so long sought after, the mother metal, "by which all other metals, if we knew how to use it, might be turned into gold? Excuse these questions, Sir; they may, perhaps, exercise the ingenuity of y'our youthful readers, as they have sometimes amused An Old Man In His Arm Chair.
TO REVIVE OLD WRITING. Boil gall-nuts ia wiDe, then with a sponge dipped in the liquid wipe over the Hues of theold writing, and all the letters will again appear distinctly visible. This should not b© attempted with documents the originals of which must be preserved, as it has a tendency to destroy the material, but only with such as are to be copied when legible.
Montis, and a former Correspondent, J. W. of Stockport, are informed, that roe find, on referring to the original of M. Dubuc's experiments, that the substance he used was not chlorate, but muriate of lime, or as it is now called by chemists, chloride of calcium; and it may be obtained by dissolving carbonate of lime in muriatic acid.
We beg to refer C. C. to Nos. III., IV. and V. of our Work; and tee shall be ready, after he has read the Articles in them on the subject to which he alludes, to give him, as far as lies in our power, any further and more specific information he may require.
J. Of. mill observe, by our Number ihisiveek, that the first pari of his Letter is in a great measure unnecessary. The suggestions as to the morle of conducting the Society are worthy of consideration; and we have, there/ore, taken the liberty of inserting this part only of his communication. If he wants the remainder of his Letter he uilljind it at the Publishers'.
The Article allMed to by our friend, A Chemist, will be inserted when the Plate is prepared.
The Letter o/'LuziTANUS, with his handsome offer to the Chemical Society, came too late for insertion this week. It will appear in our next Number.
Morphine Iodine also in our next. The request of A.M. shall be attended to; and in future Tee shall distinguish the proposer of the Chemical Society by A. M. and not A. W.
%* Communications (post paid) to be addressed to the Editor at the Publishers'.
London: Published by John Knight and Henry Lacey, 24, Paternosterrow.-^-Printed by 11. Bcnsley, Boltcourt, Fleet-street.
the last article; and as the one or two little plates we had selected to illustrate the. process were not then ready, we give them in the present Number. We shall now describe some different kinds of steel and different modes of making
It has been already stated that chemists consider wrought or hammered iron as the pure substance, steel as iron combined with'carbon, and cast iron as only differing from Steel by containing a still greater quantity of oarbon. The first mode of making steel is that which we alluded to in the last Number as being carried on in Cumberland, where, by a proper regulation of the heat, it is made from the ore.
Natural steel, however, as it is called, is made from cast iron, which is exposed to a violent heat in a furnace. Part of the carbon is then supposed to combine with the oxygen, and fly off as carbonic acid gas, while the remainder, in combination with the pure iron, constitutes it steel. This Steel is rather of an inferior quality, it is. softer than the other sorts, and being obtained by a Jess expensive process, is sold at a less price. Sled of cementation, the mode of making which was first discovered or at least first practised to any extent in Britain, is made by placing bars'of pure iron and charcoal powder alternately in large earthen troughs or crucibles, the mouths ef which are carefully closed tip with clay. These troughs are about nine feet long, and are made of a sort of Sand-stone which is not acted on by the fire. They are put into a furnace and kept for eight or ten days exposed to a considerable degree of heat, when the iron is found to be converted into steel. During this process, it gains in Weight from four to twelve ounces per hundred weight. The former proportion makes mild, the second very hard steel. If the 'heat is pushed so far as to make the steel melt, in the act of melting it will combine with a greater quantity of carbon and become cast iron. The quality of the steel thus formed depends, in some measure, on the nature of the iron employed to make it. In this state it is called blistered steel, from the bars having sometimes on their surface little blisters, as if an elastic fluid had been confined in different places. It is afterwards worked into smaller bars, and is then called tilted steel, from the name of the hammer with Which the operation is carried on. When afterwards broken to pieces, welded repeatedly, and then drawn into bars, it is called German or thear steel. It has a fine grain, is equal, harder, and more elastic than natural steel. The most valuable, the most compact in its texture, and susceptible of the most brilliant polish, is cast steel. This is used for all the finer sorts of cutting instruments, such as razors, surgeons' instruments, &c. The method of making this was discovered at Sheffield, where it still continues to be made in the greatest perfection, about 1750, by Mr. Huntsman. He is said to have added charcoal and pounded glass to blistered steel, and to have fused it in a close crucible j but as the process was long kept secret, and as it is now known that it may be made without either charcoal or glass, it is probable this was a mistake in the description. Cast steel i« only blistered steel fused in a crucible; and to obtain it of the requisite degree of hardness, it is only necessary to select blister
steel which is proportionably hard or soft. Cast steel cannot, like blistered steel, be welded to iron: because, when brought to a sufficient heat for that purpose, it falls to pieces under the blows of the hammer like a piece of sand-stoiie. There is some difficulty to explain this. If charcoal were added to the blistered steel, to make cast steel, it might be supposed that the combination of this substance caused it, and made the steel approach the state of cast iron; but, on the contrary, none is added, and some is burnt off in the process of melting. It has, indeed, been supposed, that in cast iron the carbon is only mechanically combined with the iron, while it is chemically united with it in steel. This supposition we hold to be inadmissible, and therefore the fact is at present not explained. Whether some other substances obtained from the crucibles enter into combination with the steel or not, we will not venture to give an opi* nion; but some experiments made in France, by M. Boussingault; and others made, in England by Messrs. Faraday and Stodart, would seem to show that other substances besides carbon are capable of imparting to iron the properties of steel. Indeed the French authors have gone so far as to suggest that carbon may, in all cases, be replaced by silica; and some recently discovered analogies between these two substances gives some feasibility to this suggestion. It may be, therefore, that the siliceous crucibles in which the operation is carried on may supply the proper quantity of the siliceous material, which Is, in fact, so minute as not to be detected without very delicate instruments and a very close investigation. At all events, all the facts connected with the conversion of iron into steel are not yet thoroughly explained, and we have given our readers the above outline rather as an account of the opinions at present entertained on the subject, than as being ourselves perfectly convinced that every step of the process is theoretically understood.
We cannot conclude this article without referring to the acknowledged superiority which the manufacture of iron in our country, take it altogether, has over the same manufacture in every other part of the world. The bar iron of Sweden, and the steel made in India, called woolz, and perhaps some few instruments made in France, are better than any things of the same kind manufactured in England; but, with these exceptions, the iron manufacture of Britain has no equal. It has attained its present excellence, like the cotton manufacture, without any special encouragement from the government, and without being subjected to its watchful care. No exciseman determines, by his gauge, the quantity of materials and of labour to be put into a knife or piece of calico, nor are there any specific regulations prescribing how a furnace shall be heated or a spinning-mule erected. 13ut many of the manufactures in our country, and almost all the manufactures of the Continent are carried on according to some rules laid down by government. The consequence has been, in all cases, that the manufacture least regulated and least encouraged by the government, when the circumstances of a country have been adapted to it, has been the most flourishing. It is found not only that the patronage of the public, which is never long bestowed but on objects of general utility, is the best of all encouragements, but also that this patronage is sufficient to produce the greatest possible improvement in the arts, and to check the production of spurious and base commodities. When a government sets about patronizing and Tegulating a manufacture, it does so according to some theoretical principle, and, in arbitrary governments, merely to gratify the caprice of the sovereign. Whatever is of use is, in nine cases out of ten, already patronized by the public purchasing it; and conse
quently, in nine cases out of ten, the patronage of the government is bestowed on something which is not useful to the public. As a rule, the public never buys other than useful commodities, and governments never patronize the production of any commodities which are not already sufficiently patronized, or which are nearly useless, or so costly as not to be worth the labour of producing them.
The iron manufacture throughout Germany and France is either directly under the control of the government, or greatly the object of its patronage. ' They appoint committees of scientific men to investigate its progress, to point out new methods, and to reward the skilful. The consequence of all this has been, that the manufacture in both countries is very sadly behind hand. They cast medallions, and statues, and ornaments equal to us, but they do not make even these superior. The encouragement of the public, directed in the first instance to procurings good scissors, knives, and other trilling instruments, is found to be capable of effecting far greater improvements in the arts than the patronage of governments; and we are quite confident, that there is not on the whole continent of Europe so stupendous a monument of skill in the manufacture of iron asthe bridge over the Thames. We have been induced to make these few remarks, because we observe there is scarcely a single publication which does not call for the regulation and encouragement by government of some certain manufactures. Are the colours of the dyer fugitive, ignorant persons demand that the artisan shall, by sorne penal enactment, be compelled to make them fixed. Are knives made of iron and called steel, a law is instantly required to punish the seller. Does a man, eager for trade, entice the unwary to his shop and give them bad goods at a high price, this js an evil which can only be remedied, it is immediately said, by a legislative enactment, Now, on the