III. Experimental researches in electricity. ─Twenty-fifth series

1851 ◽  
Vol 141 ◽  
pp. 29-84 ◽  
Keyword(s):  
Magnetic Force ◽  
Central Line ◽  
General View ◽  
Axial Line ◽  
Electric Induction ◽  
Other Substances ◽  
Iron Nickel ◽  
The Subject ◽  
Experimental Researches ◽  
As If

2797. The remarkable results given in a former series of these researches (2757. &c.) respecting the powerful tendency of certain gaseous substances to proceed either to or from the central line of magnetic force, according to their relation to other substances present at the same time, and yet the absence of all condensation or expansion of these bodies (2756.) which might be supposed to be consequent on such an amount of attractive or repulsive force as would be thought needful to produce this tendency and determination to particular places, have, upon consideration, led me to the idea, that if bodies possess different degrees of conducting power for magnetism, that difference may account for all the phenomena; and, further, that if such an idea be considered, it may assist in developing the nature of magnetic force. I shall therefore venture to think and speak freely on this matter for a while, for the purpose of drawing others into a consideration of the subject; though I run the risk, in doing so, of falling into error through imperfect experiments and reasoning. As yet, however, I only state the case hypothetically, and use the phrase conducting power as a general expression of the capability which bodies may possess of affecting the transmission of magnetic force; implying nothing as to how the process of conduction is carried on. Thus limited in sense, the phrase may be very useful, enabling us to take, for a time, a connected, consistent and general view of a large class of phenomena; may serve as a standard of meaning amongst them, and yet need not necessarily involve any error, inasmuch as whatever may be the principles and condition of conduction, the phenomena dependent on it must consist among themselves. 2798. If a medium having a certain conducting power occupy the magnetic field, and then a portion of another medium or substance be placed in the field having a greater conducting power, the latter will tend to draw up towards the place of greatest force, displacing the former. Such at least is the case with bodies that are freely magnetic, as iron, nickel, cobalt and their combinations (2357. 2363. 2367. &c.), and such a result is in analogy with the phenomena produced by electric induction. If a portion of still higher conducting power be brought into play, it will approach the axial line and displace that which had just gone there; so that a body having a certain amount of conducting power, will appear as if attracted in a medium of weaker power, and as if repelled in a medium of stronger power by this differential kind of action (2367. 2414.).

scholarly journals VIII. The Bakerian Lecture.—Experimental of laws of magneto-electric induction in different masses of the same metal, and of Intensity in different metals

1833 ◽  
Vol 123 ◽  
pp. 95-142 ◽  
Keyword(s):  
Great Difficulty ◽  
The Other ◽  
Present Purpose ◽  
Electric Induction ◽  
Other Substances ◽  
The Subject ◽  
The Absolute ◽  
Experimental Researches

Mr. Faraday's highly interesting papers, entitled “Experimental Researches in Electricity,” having been referred to me, to report on, by the President and Council of this Society, I necessarily entered minutely into all the experiments and conclusions of the author, and the more so that I had had the advantage of witnessing many of the most important of these experiments. It is foreign to my present purpose to descant upon the value of Mr. Faraday’s discovery, or the merits of his communication ; the President and Council have marked their opinion of these by the award of the Copley Medal: but I may be permitted to state, that no one can concur more cordially than I do in the propriety of that award. Agreeing as I did generally with the author, both in the views which he took of the subject, and in the conclusions which he drew from his experiments, there was one, however, which I felt great difficulty in adopting, viz. “That when metals of different kinds are equally subject, in every circumstance, to magneto-electric induction, they exhibit exactly equal powers with respect to the currents which either are formed, or tend to form, in them :" and that “the same is probably the case in all other substances.” Although the experiments might appear to indicate that this was possibly the case, I did not consider them to be conclusive. The most conclusive experiment, that of two spirals, one of copper and the other of iron, transmitting opposite currents, was quite consistent with the absolute equality of the currents excited in copper and iron; but, at the same time, the apparent equality of the currents might be due to their inequality being counteracted by a corresponding inequality in the facility of transmission.

V. Experimental researches in magnetism and electricity

1867 ◽  
Vol 157 ◽  
pp. 89-107 ◽  
Keyword(s):  
High Pressure ◽  
Quantitative Relation ◽  
Feed Water ◽  
Dynamic Force ◽  
Electric Induction ◽  
Similar Character ◽  
The Subject ◽  
The One ◽  
Experimental Researches ◽  
The Universe

1. The principle of the conservation of force, as I apprehend it, is the definite quantitative relation existing between all the phenomena of the universe whatsoever, both in direction and amount, whether such phenomena be considered in the relation of cause and effect, or as antecedent and consequent events. 2. In the particular application of this principle to the advancement of physical science, and also to the invention of new engines and machinery to meet the progressive requirements of society, problems not unfrequently present themselves which involve the consideration of static and dynamic force, from several different aspects; and the solution of these problems often brings out results which are as surprising as they are paradoxical. Of such cases, in which the idea of paradox alluded to is involved, may be mentioned the one contained in the 36th Proposition of Newton’s 'Principia' (Book 2, Cor. 2), and in D. Bernoulli’s 'Hydrodynamica,' p. 279; in which the repulsive force of a jet of Water issuing from a hole in the bottom or side of a vessel with a velocity which a body would acquire in falling freely from the surface, is equal to the weight of a column of water of which the base is equal to the section of the contracted vein and about twice the height of the column which produces the flowing pressure; the static force of reaction being thus double that which, without experiment, had been predicted. An instance in which the quantity of dynamic force is increased paradoxically may be seen in that curious and useful piece of apparatus the injector, by means of which a boiler containing steam of high pressure is able to feed itself with water through a hole in its shell, though this hole is open to the atmosphere; or the steam from a low-pressure boiler is enabled to drive the feed-water through a hole (also open to the atmosphere) into a high-pressure boiler. Although, when rightly interpreted, these examples of paradox, as well as many others of a similar character, are in strict accordance with the principle of conservation, yet they are at the same time contrary to the inferences which are generally drawn from analogical reasonings, and to some of those maxims of science which are framed for the instruction of the unlearned. As the examples cited are only adduced for the purpose of illustrating some analogous phenomena observed in connexion with certain combinations of static and dynamic force in molecular mechanics which form the subject of the present research, it is not my intention to enter into the rationale of either of them, but to direct attention to some new and paradoxical phenomena arising out of Faraday’s important discovery of magneto-electric induction, the close consideration of which has resulted in the discovery of a means of producing dynamic electricity in quantities unattainable by any apparatus hitherto constructed.

scholarly journals I. On magneto-electric induction in liquids and gases.—Part I. production of induced currents in electrolytes

1878 ◽  
Vol 26 (179-184) ◽  
pp. 40-43
Keyword(s):  
Sulphuric Acid ◽  
Magnetic Force ◽  
Primary Circuit ◽  
Rubber Tube ◽  
Secondary Circuit ◽  
Negative Results ◽  
Electric Induction ◽  
The Subject ◽  
Induced Currents ◽  
Solid Conductors

This paper contains an account of an experimental inquiry into the production of induced currents in liquids by magneto-electric induction. Faraday examined one such case of induction, in which a conducting liquid was used as a secondary circuit. He coiled round the armature of an electromagnet an india-rubber tube filled with dilute sulphuric acid, and found, on making and breaking the primary circuit, the induced currents generated in it, as in the case of metallic conductors; but he could not obtain any effect when brine, sulphuric acid, or other solutions were rotated in basins over a magnet, or enclosed in tubes and passed between the poles. He failed also to detect any magneto-electric current in water flowing across the earth’s lines of magnetic force (viz. in the river Thames). Since the reason for these negative results is not at once obvious, it seemed desirable to repeat and extend them to other cases, so that, if possible, the analogy of electrolytic with solid conductors might, in respect to magneto-electric induction, be completed. In addition, the subject involves the interesting question of the magneto-electric phenomena accompanying the flow of ocean-currents and other large masses of water.

scholarly journals Experimental researches in electricity

1851 ◽  
Vol 5 ◽  
pp. 592-595 ◽  
Keyword(s):  
Law Of Nature ◽  
Other Substances ◽  
The Subject ◽  
Experimental Researches ◽  
Distinct Idea

The following is the order in which the several divisions of the subject treated of in this section of the author’s researches in electricity succeed one another:—1. Apparatus required. 2. Action of magnets on heavy glass. 3. Action of magnets on other substances acting magnetically on light. 4. Action of magnets on the metals generally. 5. Action of magnets on the magnetic metals and their compounds. 6. Action of magnets on air and gases. 7. General considerations. In giving an account of the contents of this paper, any attempt to follow the track of the author in the precise order in which he relates the consecutive steps of his progress in this new path of discovery, would fail of accomplishing its object; for, by adhering to such a course, it would scarcely be possible to comprise within the requisite limits of an abstract the substance of a memoir extending, as the present one does, to so great a length, and of which so large a portion is occupied with minute and circumstantial details of experiments; or to succeed in conveying any clear and distinct idea of the extraordinary law of nature brought to light by the author, and of the important conclusions which he has deduced.

Experimental determination of the laws of magneto-electric induction in different masses of the same metal, and of its intensity in different metals

1837 ◽  
Vol 3 ◽  
pp. 177-178
Keyword(s):  
Experimental Determination ◽  
Royal Society ◽  
Iron Wire ◽  
Electric Excitation ◽  
Electric Induction ◽  
Other Substances ◽  
The Difference ◽  
Experimental Researches

The reading of Mr. Christie’s paper was resumed and concluded. Mr. Faraday, in his valuable papers entitled “Experimental Researches in Electricity,” has advanced the proposition, that “when metals of different kinds are equally subject, in every circumstance, to magneto-electric induction, they exhibit exactly equal powers with respect to the currents which either are formed or tend to form in them;” and “that the same is probably the case in all other substances.” The author not being satisfied with the conclusiveness of the experiments adduced in support of this proposition,— in order to determine its correctness, subjected different metals directly to the same degree of magneto-electric excitation, in such a manner, that the currents excited in them should be in opposite directions (as was the case in Mr. Faraday’s experiment), and also that these opposing currents should have the same facility of transmission; so that the difference of their intensities, if any existed, might admit of measurement. He then minutely describes the apparatus he contrived with this view, and which consisted of helices of copper and of iron wire, covered with silk, each making sixty-five turns, but in opposite directions, and crossing each other alternately, and surrounding a cylinder of soft iron, which was rendered magnetic by the application of the large magnet belonging to the Royal Society, which the Council had placed at his disposal while engaged in these researches. The result of the experiment showed that the force of the currents from the copper helix considerably exceeded that from the iron helix, and appeared to be even more than double. By a modification of the apparatus, he found that the intensities of the currents in the two wires were very accurately proportional to their conducting powers; and hence the uniformity of the results obtained by Mr. Faraday is easily explicable.

scholarly journals II. Experimental researches in electricity. ─twenty-fifth series

1851 ◽  
Vol 141 ◽  
pp. 7-28 ◽  
Keyword(s):  
Mode Of Action ◽  
Magnetic Force ◽  
Experimental Examination ◽  
Modes Of Action ◽  
The Subject ◽  
Experimental Researches

2718. Three can be no doubt that the magnetic force, the diamagnetic force, and the magneoptic or magnecrystallic force, will, when thoroughly understood, be found to unite or exist under one form of power, and be essentially the same. Hence the great interest which exists in the development of any one of these modes of action; for differing so greatly as they do in very peculiar points, it is hardly possible that any one of them should be advanced in its illustration or comprehension, without a corresponding advance in the knowledge of the others. Stimulated by such a feeling, I have been engaged with Plücker, Weber, Reisch and others, in endeavouring to make out, with some degree of precision, the mode of action of diamagnetic as well as magnecrystallic bodies; and the recent investigation (2640, &c.) and endeavour to confirm the idea of polarity in bismuth and diamagnetic bodies, the reverse of that in a magnet or in iron bodies, was one of the results of that conviction and desire. 2719. Having failed however to establish the existence of such an antipolarity, and having shown, as I think, that the phenomena which were supposed to be due to it are in fact dependent upon other conditions and causes, I was induced, in the search after something precise as to the nature of diamagnetic bodies, to examine another idea which had arisen in consequence of the development of magnetic and diamagnetic phenomena amongst gaseous substances: this thought, with some of the results which have grown out of it during its experimental examination, I purpose making the subject of the present paper.

scholarly journals The formation and constitution of crystals of lead salts containing water-soluble colloid

1935 ◽  
Vol 235 (749) ◽  
pp. 125-164 ◽  
Keyword(s):  
Selective Adsorption ◽  
Water Soluble ◽  
Lead Salts ◽  
The Subject ◽  
As If ◽  
Saturated Solutions

The influence of small amounts of dissolved foreign substances on the growth of crystals from saturated solutions has been the subject of much investigation. Usually the added substances have been electrolytes. Dyestuffs have not been neglected, but with some few exceptions comparatively little attention has been given to the effect of non-ionized water-soluble electrolytes such as gelatine or dextrine. As a rule, the presence of the foreign substances is found to cause the crystals to assume a different habit. Whenever this occurs the absorption must have occurred on certain crystal-faces in preference to others, but, although the added material is active by virtue of its close attachment to such faces, it is rarely found to be incorporated into the solid to any great extent. The growing crystals appear to reject the impurity—thrusting it outwards as the growth advances. The action of water-soluble colloids on the halides and certain other salts of lead is exceptional in several ways. Although when such colloids are present in small concentrations one can generally observe a modification of habit, at higher concentrations there may be little selective adsorption, and the result may be a rounded crystal on which no plane faces at all can be distinguished, as if the forces by which atoms are attracted to the structure had been equalized in every direction.

scholarly journals XIII. Experimental researches in electricity. — fourteenth series

1838 ◽  
Vol 128 ◽  
pp. 265-282 ◽  
Keyword(s):  
Electric Force ◽  
Single Experiment ◽  
Experimental Researches ◽  
As If

1667. The theory of induction set forth and illustrated in the three preceding series of experimental researches does not assume anything new as to the nature of the electric force or forces, but only as to their distribution. The effects may depend upon the association of one electric fluid with the particles of matter, as in the theory of Franklin, Epinus, Cavendish, and Mossotti; or they may depend upon the association of two electric fluids, as in the theory of Dufay and Poisson; or they may not depend upon anything which can properly be called the electric fluid, but on vibrations or other affections of the matter in which they appear. The theory is unaffected by such differences in the mode of viewing the nature of the forces; and though it professes to perform the important office of stating how the powers are arranged (at least in inductive phenomena), it does not, as far as I can yet perceive, supply a single experiment which can be considered as a distinguishing test of the truth of these various views. 1668. But, to ascertain how the forces are arranged, to trace them in their various relations to the particles of matter, to determine their general laws, and also the specific differences which occur under these laws, is as important as, if not more so than, to know whether the forces reside in a fluid or not; and with the hope of assisting in this research, I shall offer some further developments, theoretical and experimental, of the conditions under which I suppose the particles of matter are placed when exhibiting inductive phenomena.

scholarly journals I.—The Metamorphosis of the Lizard Gabbros

1886 ◽  
Vol 3 (11) ◽  
pp. 481-489 ◽  
Author(s):  
J. J. H. Teall
Keyword(s):  
Mechanical Energy ◽  
Earth Pressure ◽  
Careful Consideration ◽  
Point Of View ◽  
Igneous Rocks ◽  
General Point ◽  
Present Moment ◽  
General View ◽  
Original Rock ◽  
The Subject

If we take a general view of the present position of geological science, we are struck by the fact that, although there is substantial agreement amongst geologists on matters relating to the origin of the rocks usually designated as aqueous and igneous, the greatest diversity of opinion prevails with regard to the circumstances under which the so-called metamorphic rocks have been produced. Every fragment of evidence calculated to throw light on the origin of these rocks, therefore, deserves the most careful consideration. Of recent years special attention has been directed to the effects of mechanical energy in modifying the mineralogical and structural characters of rocks originally formed by aqueous and igneous agencies; and a suspicion has been aroused that it is in this direction that we must look for a solution of many of the problems connected with the origin of the crystalline schists. A visit to the Lizard Peninsula of Cornwall during the present summer has convinced me of the immense importance of this view so far as that district is concerned. That portion of the peninsula which lies south of a line drawn from Porthalla on the east to Polurrian Cove on the west is formed.partly of igneous rocks—such as gabbro, greenstone, serpentine, and granite—and partly of crystalline schists. The igneous rocks, in certain places, become foliated and sohistose and sometimes show a definite banding due to a variation in the relative proportions of the different constituents. In other words they present characters which are usually regarded as distinctive of the crystalline schists. There is, moreover, evidence to show that these characters are mainly the result of a yielding to earth-pressure subsequent to the consolidation of the original rock. At the present moment, having just returned from the district, I am unable to treat the subject from a general point of view with any prospect of success; but it has occurred to me that some details with regard to one of the rocks may not be without interest to members of the Association.

XVII. On the aberrations of compound lenses and object-glasses

1821 ◽  
Vol 111 ◽  
pp. 222-267 ◽  
Keyword(s):  
Mathematical Theory ◽  
The Subject ◽  
Experimental Researches ◽  
Analytical Skill

It has not unfrequently of late been made a subject of re­proach to mathematicians who have occupied themselves with the theory of the refracting telescope, that the practical be­nefit derived from their speculations has been by no means commensurate to the expenditure of analytical skill and labour they have called for, and that from all the abstruse researches of Clairaut, Euler, D'Alembert, and other celebrated geometers, nothing hitherto has resulted beyond a mass of complicated formulæ, which, though confessedly exact in theory, have never yet been made the basis of con­struction for a single good instrument, and remain therefore totally inapplicable, or at least unapplied, in practice. The simplest considerations, indeed, suffice for the correction of that part of the aberration which arises from the different refrangibility of the differently coloured rays; and accord­ingly, this part of the mathematical theory of refracting telescopes was soon brought to perfection, and has received no important accession since the original invention of the achromatic object-glass. Indeed the theoretical considera­tions advanced on this part of the subject by Euler and D'Alembert have even had a tendency to retard its advancement, by appearing to establish relations among the relative refractive powers of media on rays of different colours which later experimental researches have exploded.

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