XIII. Introductory research on the Induction of magnetism by electrical currents

1856 ◽  
Vol 146 ◽  
pp. 287-295
Keyword(s):  
Copper Wire ◽  
The Other ◽  
Electrical Currents ◽  
Molecular Changes ◽  
General Law ◽  
Linear Dimensions ◽  
The Subject ◽  
Different Dimensions ◽  
Different Diameters ◽  
Experimental Researches

The researches of Jacobi and Lenz led them some years ago to the announcement as a law, that when two bars of iron of different diameters but equal to one another in length and surrounded with coils of wire of the same length carry equal streams of electricity, the magnetism developed in the bars is proportional to their respective diameters. Experiments which I made about the same time threw doubts on my mind as to the general accuracy of the above proposition, for I found that the magnetism induced in straight bars of a variety of dimensions varying from ⅓ to 1 inch in diameter, and from 7 inches to one yard in length, was nearly proportional to the length of the wire and the intensity of the current it conveyed, irrespectively of the shape or magnitude of the bars. The valuable experimental researches which have recently been made by Weber, Robinson, Müller, Dub and others, refer chiefly to the attraction of the keeper or submagnet, and are not calculated to confirm or disprove either of the above propositions; and the correct view is probably that of Professor Thomson, who considers both of them as corollaries (applying to the particular conditions under which the experiments were made) of the general law, that “similar bars of different dimensions, similarly rolled with lengths of wire proportional to the squares of their linear dimensions and carrying equal currents, cause equal forces at points similarly situated with reference to them*.” I have been induced to undertake some further experiments with an endeavour to elucidate the subject, and also to open the way to the investigation of the molecular changes which occur during magnetization. I procured four iron bars one yard long and of the respective diameters and 1/6, ¼, ½ and 1 inch, their weights being 1736, 3802, 14560, and 55060 grs. Each bar was wound with 56 feet of copper wire 1/40th of an inch in diameter covered with silk, the number of convolutions being 1020, 712, 388, and 207 respectively. The smallest bar was closely covered throughout its entire length, but on account of the larger surface of the other bars the coils had to be distributed upon them as evenly as possible. Four other bars were also procured of the same diameters as the above. They were however twice as long, weighing 3500, 7624, 29944, and 108574 grs., and were wrapped with double the length of wire, forming 2060, 1435, 768, and 418 convolutions respectively.

scholarly journals Experimental researches in electricity

1837 ◽  
Vol 3 ◽  
pp. 91-93
Keyword(s):  
Electric Current ◽  
Copper Wire ◽  
The Other ◽  
Great Length ◽  
Electrical Currents ◽  
Electric Current Passing ◽  
Electrical Condition ◽  
The Moment ◽  
Electrical Induction ◽  
Experimental Researches

This paper is divided into four parts: the first being on the Induction of Electric Currents; the second, on the Evolution of Electricity from Magnetism; the third, on a new Electrical Condition of Matter; and the fourth, on Arago’s Magnetic Phænomena. The author defines electrical induction to be the power which electrical currents possess of inducing any particular state upon matter in their immediate neighbourhood. A great length of copper wire, 1-20th of an inch in diameter, was wound round a cylinder of wood so as to compose two helices, the coils of which were intermixed, but prevented from touching each other by interposed threads of twine and calico. One helix was connected with a voltaic battery, and the other with a galvanometer. No effect was perceived on the latter, with a battery of 10 plates; a slight effect only with one of 100 plates; and a distinct deflection of the needle of the galvanometer occurred when the contact was made with a battery of 120 plates. While the contact was preserved, the needle returned to its natural position, and was unaffected by the electric current passing through the wire connected with the battery; but on breaking the connexion, the needle of the galvanometer was again deflected, but in a direction contrary to that of its former deflection. Hence it is inferred that the electric current sent by the battery through one wire, induced a similar current through the other wire, but only at the moment the contact was made; and a current in the contrary direction when the passage of the electricity was suddenly interrupted. These transitory currents, resembling waves, were found to be capable of magnetizing needles placed within the helix. Collateral currents, either in the same or in opposite directions, exert no permanent inductive power on each other.

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.

scholarly journals On the expediency of assigning specific names to such functions of simple elements as represent definite physical properties; with the suggestion of a new term in mechanics; illustrated by an investigation of the machine moved by recoil, and also by some observations on the steam engine

1833 ◽  
Vol 2 ◽  
pp. 299-300
Keyword(s):  
Physical Properties ◽  
Effective Action ◽  
The Other ◽  
Steam Engine ◽  
Similar Function ◽  
Centre Of Gravity ◽  
Elastic Bodies ◽  
General Law ◽  
The Subject ◽  
The Common

The author commences this paper by stating the necessity of distinguishing by separate appellations all such functions as measure the intensity of physical properties, which he considers rendered obvious by a reference to the controversy respecting motion. The subject of this controversy, he observes, was the measure of motion itself, it being contended on one hand that the motion of a body is always proportional to its weight multiplied by its velocity; this opinion being supported by reference to the properties of the common centre of gravity of systems, &c.; while on the other hand the affections of elastic bodies in collision, and the general law of the conservation of living or active forces, were adduced in support of the latter measure. No sooner, however, were the terms “momentum” and “impetus” introduced into the science of mechanics, than the opinions of the contending parties were reconciled by the removal of every ground of dispute. In the Bakerian lecture on the force of percussion, read to this Society in 1806, he observes, it is remarked, that neither impetus nor momentum are usually correct measures of the effective action of machines. The criterion of this is the force exerted, multiplied by the space through which it acts, and this measure numerically expressed has been denominated duty by Mr. Watt; and the raising of one pound one foot high has been by him made the dynamic unit; according to which estimate, the duty performed by one bushel of coals, of 84 pounds, has been found to vary from 30 to 50 millions of such units, according to the nature of the engine, and the mode of combustion. To the measure or function represented by the force applied, multiplied by the space through which it acts, the author, however, proposes to give the name efficiency, retaining the word duty for a similar function, indicative of the work performed; and by a comparison of these two functions, viz. the efficiency expended on, and the duty performed by, any machine, an exact measure of its intrinsic work will be obtained.

scholarly journals XXI. Experimental researches on atomic weights

1833 ◽  
Vol 123 ◽  
pp. 523-544 ◽  
Keyword(s):  
First Principles ◽  
Atomic Weight ◽  
Point Of View ◽  
Relative Accuracy ◽  
The Other ◽  
Present Communication ◽  
Present Essay ◽  
The Subject ◽  
Important Object ◽  
Experimental Researches

The present communication may be viewed as the continuation of an Essay on the Composition of the Chloride of Barium, which was honoured with a place in the Philosophical Transactions for the year 1829. In resuming the subject after such a long interval, I feel it right to apologize to the Society for the unfinished state in which that Essay has hitherto been left,—an omission far from voluntary, and entirely due to circumstances not subject to my own controul. In one point of view, however, the delay has been advantageous: it has afforded an opportunity to chemists to verify or correct the results contained in my first Essay, and has enabled me to repeat and extend my researches. The object which I proposed to myself in commencing the present inquiry, was to re-examine some of those estimates which chemists have occasion to use continually as elements in their calculations, and to confide in as the foundation of their doctrines. With this view I undertook to determine the relative accuracy of the atomic weights which the British and Continental chemists respectively employ; and several circumstances induced me to begin by analysing the chloride of barium. Dr. Thomson, on whose experiments the British chemists relied, had obtained so many of his results by means of the chloride of barium, that any material error in the constitution of that compound would necessarily vitiate a large part of his table of equivalents; and if, on the other hand, the estimate of Dr. Thomson proved to be correct, an important error would be chargeable against Berzelius, whose numbers are very generally adopted on the Continent. The result of the inquiry is now well known: the source of fallacy, pointed out in my first communication, has been admitted by Dr. Thomson in the new edition of his System of Chemistry, and he has accordingly changed the equivalent of barium from 70 to 68. The inevitable consequence of this change must be apparent to every one who is acquainted with the method of analysis so frequently resorted to by Dr. Thomson. Many of the experiments described in his First Principles of Chemistry are now at irreconcilable variance with each other, and, if relied upon at all, subvert the conclusions which they once appeared to establish. Nor can those parts of his work which are not subject to this criticism be safely applied to the purposes of science. His view, for instance, of the composition of the compounds of oxygen with phosphorus, arsenic, and antimony, has been lately abandoned by himself; and in the course of the present Essay I shall have occasion to prove, that the atomic weights which he has employed for silver and chlorine are likewise inadmissible. His analysis of sulphate of zinc, which was made, to use Dr. Thomson’s own words, “the foundation on which he endeavoured to rear the whole subsequent doctrine of the atomic weight of bodies,” is peculiarly objectionable. Besides being vitiated by his error in the equivalent of barium, the oxide of zinc was determined by a method which involved an error in principle, and was in practice so complex as to be unfit for the extremely important object which it was intended to serve.

scholarly journals IV. An account of two cases, in which ovules, or their remains, were discovered in the fallopian tubes of unimpregnated women who had died during the period of menstruation

1852 ◽  
Vol 142 ◽  
pp. 57-64 ◽  
Keyword(s):  
Fallopian Tube ◽  
Seminal Fluid ◽  
Direct Action ◽  
The Other ◽  
Fallopian Tubes ◽  
Human Female ◽  
Human Species ◽  
Graafian Follicle ◽  
The Subject ◽  
Experimental Researches

The observations that have been made at various times, during the last thirty years, by Messrs. Power, Lee, Barry, Wharton Jones, Girdwood, and others in this country, together with the experimental researches of MM. Valentin, Gendrin, Wagner, Bischoff, Pouchet and Raciborski on the Continent, have, I think, clearly proved that the phenomena manifested during the period of the catamenia in women, are closely connected with those observed during the time of heat or rut in quadrupeds; and that both of these phenomena are dependent on one cause, namely, the maturation of ovules. But while this hypothesis has been very generally admitted, there is, I believe, a tendency in the minds of many physiologists of the present day, to doubt whether the ovules so matured are ever extruded from the ovary and carried into the Fallopian tubes, without the stimulus of impregnation, or, at any rate, without the congress of the male. In support of this view, or rather of these doubts, an appeal is often made to the fact, that an ovule has never yet been detected in either of the Fallopian tubes of a virgin, who has died during the period of the catamenia, notwithstanding that many subjects have been examined, that most careful search has been instituted, and that appearances have frequently been noticed indicating the recent rupture of a Graafian follicle. In point of fact, it is imagined by those who entertain such doubts, that the fecundation of the germ takes place while it is within the Graafian follicle, and consequently, that if the ovule fails to be the subject of impregnation it never quits the ovary, but perishes within its formative vesicle. On the other hand, the researches of Bischoff have led him to enunciate a law, the purport of which is the very reverse of the preceding; for he says, that “the ovules formed in the ovaries of females of the human species and of mammiferous animals, undergo a periodical maturation, quite independently of the male seminal fluid. At these periods, known as those of heat or the rut in animals, and menstruation in the human female, the ovules which have become mature, disengage themselves from the ovary and are extruded. If the union of the sexes takes place, the ovule is fecundated by the direct action of the semen upon it. If no union of the sexes occurs, the ovule is nevertheless extruded from the ovary, and enters the Fallopian tube, but there perishes.” The law, as thus expressed, is in conformity with the opinions entertained by Drs. Robert Lee, Paterson, Girdwood, Gendrin, Pouchet, Raciborski, Mr. Wharton Jones, and many other authorities of the present time. It is also in accordance with the more ancient doctrines of Malpighi, Sir Everard Home, and Dr. Power. Nevertheless, as the truth of this law, in its application to the human female, appears to be still open to the evidence of positive proof, I have thought it desirable to publish a report of the two following cases.

scholarly journals XVIII. On the development of Carcinus mænas

1857 ◽  
Vol 8 ◽  
pp. 544-546
Keyword(s):  
Carcinus Maenas ◽  
Posterior Segment ◽  
The Other ◽  
Adult Type ◽  
General Law ◽  
Other Hand ◽  
Perfect Form ◽  
History Of ◽  
The Subject ◽  
Larval Condition

The author, after noticing the history of the subject, and the opposition which the assertion, “that the Zoë of naturalists is the larva of a common crab,” received, traces the progress of the development of the animal from the Zæa to the adult, and endeavours to demonstrate, that from the youngest to the most perfect form, the changes are the result of no sudden transformation, but produced by a gradual series of alterations contemporary with every succeeding moult; that the Zæa is connected with the Megalopa , and the latter with the adult by many intermediate gradations, each in itself scarcely appreciable, and progressively approximating nearer and nearer the more perfect stages. The author asserts that the development is earliest and most complete anteriorly; that when first born, the seventh or posterior segment of the head, one or more of the posterior segments of the pereion (thorax), and the penultimate of the pleon (abdomen) are wanting in the brachyurous Decapods; but that this general law loses somewhat of its force in the descending scale of development; and as it becomes less persistent, the animal approximates in the larval condition nearer to the form of the adult type; while on the other hand, the same appears to be a constant law of the depreciation in adult forms, as exhibited in the more or less aberrant Amphipoda, such as Cyrtophium, Dulichia , &c.

Report on experimental researches in electricity:- Third series

1837 ◽  
Vol 3 ◽  
pp. 191-194
Keyword(s):  
Corrosive Sublimate ◽  
Chemical Decomposition ◽  
General Law ◽  
Principal Points ◽  
The Subject ◽  
Reasonable Ground ◽  
Experimental Researches ◽  
Magnetic Needle ◽  
Different Sources ◽  
Decomposition Of Water

In order to prove the identity of electricities derived from different sources, the author in this communication, after viewing the phenomena exhibited by electricity, shows, that although some effects are most readily derived from a particular source, yet none are peculiar to such source. The principal points in which ordinary and voltaic electricity have been considered to differ, are the inefficiency of ordinary electricity to produce chemical decomposition, or to affect a magnetic needle like voltaic electricity. The experiments of Wollaston were made early in the application of electricity to chemical decomposition, before the general law of the transfer of the elements to the poles of the battery had been indicated; yet his 4th experiment, in which electricity from the machine was passed through a solution of sulphate of copper, and his 5th, where it was passed through a solution of corrosive sublimate, have the true characteristic of decomposition by voltaic electricity: and it is surprising that those who advocate a distinction between these electricities should have ventured to overlook these experiments, when they bring forward the experiment of the decomposition of water, as deficient in this characteristic of the transfer of the elements. This circumstance, however, induced Mr. Faraday not merely to repeat Wollaston’s 4th experiment, which he did with complete success, but to adopt different arrangements and by these, with ordinary electricity, he obtained, in various instances, chemical decompositions having all the characters of decomposition by voltaic electricity. Whatever doubt, therefore, may have been thrown upon this part of the subject, he has entirely removed it. The author has also removed the doubts which it appears had been entertained respecting the conclusion of M.Colladon, in consequence of the failure of his experiments in the hands of others. By a particular arrangement connected with the glass inclosing the galvanometer, and by retarding the passage of the electricity through its wires, by means similar to those by which gunpowder is roost successfully exploded by an electric discharge, which he also employed to effect chemical decomposition, Mr. Faraday succeeded in causing the needle to deviate, both by the discharge of a battery, and by electricity passing directly from the conductor of the machine. In justice to M. Colladon, we must remark, that the account which he gives of his experiments affords no reasonable ground for doubting the accuracy of his conclusions: the details are clear, and the numerous results unequivocal. We may also notice, that, in the same memoir, M. Colladon gives an account of some very interesting experiments, made with a similar arrangement, on the magnetical effects of atmospherical electricity, by which its power of causing deviations of the needle is satisfactorily established.

scholarly journals Experimental researches in voltaic electricity

1837 ◽  
Vol 3 ◽  
pp. 98-101
Keyword(s):  
Copper Wire ◽  
Electric Circuit ◽  
Dissimilar Metals ◽  
Square Root ◽  
Liquid Part ◽  
Magnetic Action ◽  
Electro Magnetic ◽  
Different Diameters ◽  
Experimental Researches ◽  
Dilute Nitric Acid

The author adduces many facts in refutation of the theory by which Volta endeavoured to explain the development of electricity in galvanic circles. He shows that the contact of dissimilar metals is not necessary for producing that effect, for galvanic action may be obtained by employing only one metal, if the two ends of the same copper wire be coiled into helices of different diameters, and immersed into dilute nitric acid. The experiments of Mr. Parrot of St. Petersburgh are cited as leading to results totally different to those on which Volta rested the foundations of this theory. The author points out several important marks of distinction between voltaic and common electricity, and denies that the latter is capable of passing into the former. He shows by an experiment that the free electricity developed by heat is independent of that developed by galvanic action. Chemical decompositions are effected in a totally different manner by voltaic and by ordinary electricity; for in the former case the two elements of the decomposed substance are found disengaged at the opposite poles, but in the latter they are developed at the same point, and appear more as the effect of a cleavage of the molecules by the mechanical agency of electricity. The author conceives that in a galvanic circle of zinc and copper with interposed water, the superior attraction of the zinc for oxygen produces an arrangement of the molecules of the water such that the particles of oxygen entering into the composition of each are all turned towards the zinc. This definite arrangement produces in its turn, by production on the neutral electric fluid contained in the metal, a corresponding definite arrangement of the two electricities along the whole electric circuit. Hence electro-magnetic effects may be obtained without any chemical decomposition; this latter effect taking place only when the attraction of the metal for one of the elements of the fluid is greater than that between the two elements of the fluid: and upon this principle the author conceives that the phænomena of the secondary piles of Ritter, and those observed by M. de la Rive, may be explained. By adopting the theory of the successive decomposition and recomposition of each particle of fluid in the line of action, we avoid the necessity of supposing the transference of the disengaged element through the intervening mass of fluid. Whatever circumstance favours the decomposition of the water, will also increase the power of the voltaic arrangement. Conformably to these views we find that all liquids whose component parts go to the same pole are non-conductors of voltaic electricity. A given section of a liquid is capable of conducting only a limited quantity of electric influence. It was also found by experiment that when sulphuric acid was employed, the quantity of electro-magnetic action in the connecting wire is exactly proportional to the quantity of water decomposed in the liquid part of the circuit. This quantity is, within certain limits, inversely proportional to the square root of the distance between the plates.

IV. Experimental researches in electricity.—Third series

1833 ◽  
Vol 123 ◽  
pp. 23-54 ◽  
Keyword(s):  
Royal Society ◽  
The Other ◽  
Chemical Action ◽  
Chemical Decomposition ◽  
General Impression ◽  
Electricity And Magnetism ◽  
The Subject ◽  
Humphry Davy ◽  
Experimental Researches ◽  
Different Sources

265. The progress of the electrical researches which I have had the honour to present to the Royal Society, brought me to a point at which it was essential for the further prosecution of my inquiries that no doubt should remain of the identity or distinction of electricities excited by different means. It is perfectly true that Cavendish, Wollaston, Colladon and others, have in turn removed some of the greatest objections to the acknowledgement of the identity of common, animal and voltaic electricity, and I believe that philosophers generally consider these electricities as really the same. But on the other hand it is also true, that the accuracy of Wollaston’s experiments has been denied, and that one of them, which really is no proof of chemical decomposition by common electricity (309. 327.), has been that selected by several experimenters as the test of chemical action (336. 346.). It is a fact, too, that many philosophers are still drawing distinctions between the electricities from different sources; or at least doubting whether their identity is proved. Sir Humphry Davy, for instance, in his paper on the Torpedo, thought it probable that animal electricity would be found of a peculiar kind; and referring to that, in association with common electricity, voltaic electricity and magnetism, has said, “Distinctions might be established in pursuing the various modifications or properties of electricity in these different forms, &c.” Indeed I need only refer to the last volume of the Philosophical Transactions to show that the question is by no means considered as settled. 266. Notwithstanding, therefore, the general impression of the identity of electricities, it is evident that the proofs have not been sufficiently clear and distinct to obtain approbation from all those who were competent to consider the subject; and the question seemed to me very much in the condition of that which Sir H. Davy solved so beautifully,—namely, whether voltaic electricity in all cases merely eliminated, or did not in some actually produce, the acid and alkali found after its action upon water. The same necessity that urged him to decide the doubtful point, which interfered with the extension of his views, and destroyed the strictness of his reasoning, has obliged me to ascertain the identity or difference of common and voltaic electricity. I have satisfied myself that they are identical, and I hope the proofs I have to offer, and the results flowing from them, will be found worthy the attention of the Royal Society.

scholarly journals Experimental researches in electricity—Second series

1837 ◽  
Vol 3 ◽  
pp. 95-97
Keyword(s):  
Electrical Machines ◽  
Electric Currents ◽  
Electrical Currents ◽  
The Earth ◽  
The Subject ◽  
The Moment ◽  
Magnetic Poles ◽  
Experimental Researches ◽  
Contrary Direction

The success of the author in exhibiting the evolution of electricity by induction from ordinary magnets, led him to conclude that similar effects might be obtained from the magnetism of the earth, and even to an extent that might render it available in the construction of new electrical machines. These expectations have been fully realized; and the researches which establish the influence of terrestrial induction in giving rise to electrical currents, form the subject of this second paper. Whenever a hollow helix, the terminal wires of which were connected with those of a galvanometer, and which inclosed a cylinder of soft iron, was held with its axis in the line of the magnetic dip, and suddenly inverted, the evolution of electric currents was immediately rendered sensible by the deflection of the needle of the galvanometer; a deflection in the contrary direction being produced the moment the helix was again inverted, so as to recover its first position. The same effect resulted from the simple introduction of the iron cylinder into, or its removal out of, the helix; evidently in consequence of the magnetism acquired by position with relation to the magnetic poles of the earth. When a cylindric magnet was substituted for the soft iron, the same phænomena, obviously ascribable to terrestrial induction, were in either case observed. Similar but more feeble indications of the same effect were obtained by inverting the helix alone, without its association with any ferruginous body whatever.

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