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Mechanics magazine
- Bandzählung
- N.S. 5=74.1861
- Erscheinungsdatum
- 1861
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- Englisch
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- A146
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- Universitätsbibliothek Chemnitz
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- Universitätsbibliothek Chemnitz
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Mechanics magazine
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Band N.S. 5=74.1861
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- Titelblatt Titelblatt -
- Register Index I
- Ausgabe January 4, 1861 1
- Ausgabe January 11, 1861 19
- Ausgabe January 18, 1861 33
- Ausgabe January 25, 1861 49
- Ausgabe February 1, 1861 69
- Ausgabe February 8, 1861 85
- Ausgabe [February 15, 1861] -
- Ausgabe February 22, 1861 121
- Ausgabe March 1, 1861 137
- Ausgabe March 8, 1861 153
- Ausgabe March 15, 1861 173
- Ausgabe March 22, 1861 189
- Ausgabe March 29, 1861 211
- Ausgabe April 5, 1861 227
- Ausgabe April 12, 1861 243
- Ausgabe April 19, 1861 259
- Ausgabe April 26, 1861 281
- Ausgabe May 3, 1861 297
- Ausgabe May 10, 1861 313
- Ausgabe May 17, 1861 329
- Ausgabe May 24, 1861 345
- Ausgabe May 31, 1861 361
- Ausgabe June 7, 1861 377
- Ausgabe June 14, 1861 393
- Ausgabe June 21, 1861 409
- Ausgabe June 28, 1861 425
- Ausgabe No. 106 I
- Ausgabe No. 107 I
- Ausgabe No. 108 I
- Ausgabe No. 109 I
- Ausgabe No. 110 I
- Ausgabe No. 111 I
- Ausgabe No. 112 I
- Ausgabe No. 113 I
- Ausgabe No. 114 I
- Ausgabe No. 115 I
- Ausgabe No. 116 I
- Ausgabe No. 117 I
- Ausgabe No. 118 I
- Ausgabe No. 119 I
- Ausgabe No. 120 I
- Ausgabe No. 121 I
- Ausgabe No. 122 I
- Ausgabe No. 123 I
- Ausgabe No. 124 I
- Ausgabe No. 125 I
- Ausgabe No. 126 I
- Ausgabe No. 127 I
- Ausgabe No. 128 I
- Ausgabe No. 129 I
- Ausgabe No. 130 I
- Ausgabe No. 131 I
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THE MECHANICS’ MAGAZINE. LONDON, FRIDAY, JANUARY\\, 1861. THE CONDENSATION OF STEAM. Those of our readers who followed us carefully through the series of articles on Mr. C. Wye Williams’s new work on Steam,* which we re cently gave, will have discovered for themselves that the novel and fascinating doctrines which he has propounded must possess important bear ings upon the existing theory of steam conden sation. This is unquestionably the fact. Mr. Williams’s views of condensation are of so startling a nature, that we propose to state them here as nearly as possible in his own language. The Encyclopaedia Britannica says :—“ The “ term condensation is commonly applied to the “ conversion of vapour into water in the process “of distillation. The way in which vapour “ commonly condenses, is by the application of “some cold substance. On touching it, the “ vapour parts with its heat, and, doing so, it “immediately loses the proper characteristics “of vapour, and becomes water.” We have here, Mr. Williams admits, a correct description both of the cause and process of condensation, or the reconversion of vapour into the state of a liquid. He therefore applies it to the con denser of the steam engine. The steam, by virtue of its elasticity, rushes into the con denser, he says, as it does into the worm pf the still, but what “ cold substance” does it there encounter ? This is the all-important point of the inquiry. The universally-received theory is, that meeting a body of cold water, it imparts its heat to the latter, and is thereby instantly condensed, or reconverted into the liquid state. But one of the objects of the new treatise is to show that this theory is altogether fallacious, and that water is not a substance to which vapour can give out its heat. “ It will, doubt- “ less, hereafter be a matter of special wonder,” the author thinks, “ how long we have eonfid- “ingly adopted a theory without inquiry, in “ the face of the many anomalies which it “ presents arising from the assumption of water “ being on the one hand an absorber of heat, “ and on the other a non-conductor of heat.” In common with others, he formerly considered that heat was absolutely absorbed by the water, which still retained its liquid form, and that the vacuum produced in the cylinder was rightly attributed to the steam giving out its heat to the water. It was only under an irre sistible conviction, arising out of numerous experimental proofs, he says, that “ the error “ under which we have been so long labouring” became apparent. If water could convert vapour into the liquid state, by abstracting its heat, the inevitable result must be, Mr. Williams contends, that vapour could never be formed, or, at least, have any dynamic effect. The moment the first atom of the liquid was converted into one of vapour by the heat, it would as instantaneously be re converted by the mass of water surrounding it. It appears impossible to reject this inference. Thus, no continuance could exist, and no body of vapour could be formed. That the vapour is not reconverted into water, or annihilated as soon as formed, is at once established by its rising out of the water with all its properties and characteristics unimpaired, and, so to speak, appearing in propria persona. It has already been shown that when water is placed in * OnHeatin its Relations to Water and Steam; embracing New Viewsof Vaporization, Condensation, and Explosions. By C. Wye Williams, A.I.C.E., &c., &e. London : Long man, Green, Longman, and Roberts, i860. a glass beaker, with a gas burner under it, and a glass saucer or large dial (also containing water) is placed on the former, the rising vapour will exercise its power, and increase the so-called temperature of the water in the saucer, from the first minute after the heat has been applied to the bSaker. In limine then we are com pelled to admit that the heat has not been retained in the water, but has passed away in vapour. We think it will be difficult to prove this reasoning unsound. Let us, however, see what is Mr. Williams’s view of what really takes place when vapour is thrown into what may correctly be called an atmosphere of water. Each atom is at once compressed, or reduced in influence, and prevented exercising its full ex pansive power by the combined densities of the two media—the water and the air : no diminu tion, however, of the temperature of the vapour atoms follows. They merely remain, with their compressed volumes in the water, until they escape into the atmosphere, or, by contact with some cold substance, lose their heat, and are then reconverted into the liquid form. If this view be correct, then water, or, indeed, any liquid, cannot be considered as a substance to which heat can be imparted. In a word, heat cannot be received and retained by liquid par ticles, each of which is susceptible of an instan taneous change in its own statical, or electrical condition, by the accession of heat. As well might we expect that atoms of ice could receive and absorb heat, and have their temperatures raised, yet still retain their crystallized form and status of ice, as that those of water could receive it, and retain their status of liquidity. Air is an elastic fluid, and a recipient of heat, since its status cannot be altered by it, there being no fourth state into which it might enter by a further accession of heat. Besides, being also a conductor of heat, it is capable of re ceiving and imparting it to others, from atom to atom. In this way the vapour in the atmo sphere, when brought into contact with a body of colder air, and more or less of the vapour atoms (according to the amount of atomic contact realised between them), gives out its heat to those of the air, returns to the liquid form, and produces the effect of visible clouds. When, also, wo consider the extreme miscibility of elastic fluids, or aeriform matter, and the extent of surface for mutual contact presented by the aggregation of the myriads of atoms which compose bodies of air and vapour, we can readily account for the rapid condensation of the vapour atoms in the atmosphere, when brought into connexion or collision with cur rents of colder air. To these currents may be attributed all atmospheric changes of tempera ture and humidity, from clouds, fogs, and rain, up to the more rapid discharges accompanying electric disturbance. “ If, also, we look to the “ change in the electric condition of each of “ these vapour atoms, on losing the property of “ repulsion concurrently with the Toss of heat, " and thus ■Becoming negatively electrified, we “ have a key to the great quantity and intensity “ of the electric fluid that will bo set at “ liberty.” The Encyclopedia, Britannica continues— “ If heat be withdrawn from steam or vapour, “ it no longer remains in the vaporous state, but “ resumes a liquid form. In this state it undor- “ goes a great diminution of bulk ;—a large “ volume of steam forming only a few drops of “ liquid. Hence the process by which the “ vapour passes from the aeriform to the liquid “ state is called condensation.” Here the return to the state of liquid is correctly attributed to its loss of heat, while it leaves the main question still untouched, namely, by what means this heat has been abstracted, and to what has it been transferred ? On the ordinary theory it is assumed that the cold water has absorbed the heat, thus reducing it to the state of liquid. In a word, “ annihi lating it” as vapour. This error must, Mr. Williams argues, be abandoned before we are in a position to proceed ; for, until the true re cipient of the heat be determined, we must remain in the dark as to the principle on which condensation is effected, and the best means of producing it in the steam-engine. The unsatisfactory state of the question, as to the best system of condensation, is suffi ciently shown, as Mr. Williams ingeniously ob serves, by the number of patents which continue to be taken out on the subject, and the increas ing interest exhibited in discussing the respec tive merits of what are termed surface condensers. Hall’s well-known system was a true surface condensation—identical with that of the still, and would have been as unobjectionable in practice as in principle, but for certain mecha nical difficulties which (he thinks) were found irremediable in its application. The rapidity with which vapour parts with its heat (he also observes) is truly remarkable, though not suffi ciently attended to in practice, while it furnishes a strong confirmation of the view taken by him— namely, that of the vapour being a mere aggre gate of atoms, each of which has its unit of heat in combination, all being capable of part ing simultaneously with these respective units ; for whatever may be the myriads of such atoms, the result would be equally instantaneous; hence the importance of the extended surface, or units of surface, for contact. Faraday, in reference to the process of con densation, and the reconversion of vapour into liquids, thus refers to the action of the still “ The vapour having reached the worm, is there “ to be condensed ; the worm is, therefore, put “ into a tub, and surrounded with cold water, “ the low temperature of which (the worm) “ causes the substance to lose its elastic form, “ and flow out in the liquid state.” Here the heat is correctly shown to be transferred to the metallic refrigerator by true surface condensa tion. But when steam is ejected into a body of cold water, the heat is not (according to Mr. Williams’s theory) taken from it, as in the case of the still. The steam is merely diffused through the water, its atoms becoming arranged at distances proportional to the quantity or bulk of water present. We also find its several atoms reduced in volume, in the ratio of the density of the liquid medium into which it is passed, whether that bo water, alcohol, sulphuric acid, or any other liquid. In all cases the indi cated temperature shows a rapid homogeneity in the mass. If then, with Professor Silliman, we consider this homogeneity to be the result of the mutual repellent principle among its particles, the whole becomes at once intelligible. Watt’s theory boing- eo -universally-adopted, is quoted by Mr. Williams in his own words. Writing in the third person (as instruction to his counsel in reference to the opposition his patent experienced), under the head of “A Plain “ Story,” he has thus given the history of his groat discovery, and the use and effect of the separate vessel—the condenser. Ho laid it down that— “ To make a perfect engine it was necessary “ that the cylinder should bo always as hot as “ the steam which entered it, and that the steam “ should be cooled down to below 100 degs., in “ order to exert its full power.” This reference to 100 degs., which, nevertheless, seems incon sistent with a perfect vacuum, was probably occasioned by finding that that was, practically, the lowest temperature he was able to obtain, lie then concludes:—“ The gain would lie
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