Experimental Researches in Electricity, Volume 1

Part 1

EXPERIMENTAL RESEARCHES IN ELECTRICITY

MICHAEL FARADAY, D.C.L. F.R.S.

Fullerian Profesor of Chemistry in the Royal Institution. Corresponding Member, etc. of the Royal and Imperial Academies of Science of Paris, Petersburgh, Florence, Copenhagen, Berlin, Gottingen, Modena, Stockholm, Palermo, etc. etc.

In Two Volumes

VOL. I.

Second Edition

Reprinted from the PHILOSOPHICAL TRANSACTIONS of 1831-1838.

London: Richard and John Edward Taylor, Printers and Publishers to the University of London, Red Lion Court, Fleet Street

1849

PREFACE

I have been induced by various circumstances to collect in One Volume the Fourteen Series of Experimental Researches in Electricity, which have appeared in the Philosophical Transactions during the last seven years: the chief reason has been the desire to supply at a moderate price the whole of these papers, with an Index, to those who may desire to have them.

The readers of the volume will, I hope, do me the justice to remember that it was not written as a whole, but in parts; the earlier portions rarely having any known relation at the time to those which might follow. If I had rewritten the work, I perhaps might have considerably varied the form, but should not have altered much of the real matter: it would not, however, then have been considered a faithful reprint or statement of the course and results of the whole investigation, which only I desired to supply.

I may be allowed to express my great satisfaction at finding, that the different parts, written at intervals during seven years, harmonize so well as they do. There would have been nothing particular in this, if the parts had related only to matters well-ascertained before any of them were written:--but as each professes to contain something of original discovery, or of correction of received views, it does surprise even my partiality, that they should have the degree of consistency and apparent general accuracy which they seem to me to present.

I have made some alterations in the text, but they have been altogether of a typographical or grammatical character; and even where greatest, have been intended to explain the sense, not to alter it. I have often added Notes at the bottom of the page, as to paragraphs 59, 360, 439, 521, 552, 555, 598, 657, 883, for the correction of errors, and also the purpose of illustration: but these are all distinguished from the Original Notes of the Researches by the date of Dec. 1838.

The date of a scientific paper containing any pretensions to discovery is frequently a matter of serious importance, and it is a great misfortune that there are many most valuable communications, essential to the history and progress of science, with respect to which this point cannot now be ascertained. This arises from the circumstance of the papers having no dates attached to them individually, and of the journals in which they appear having such as are inaccurate, i.e. dates of a period earlier than that of publication. I may refer to the note at the end of the First Series, as an illustration of the kind of confusion thus produced. These circumstances have induced me to affix a date at the top of every other page, and I have thought myself justified in using that placed by the Secretary of the Royal Society on each paper as it was received. An author has no right, perhaps, to claim an earlier one, unless it has received confirmation by some public act or officer.

Before concluding these lines I would beg leave to make a reference or two; first, to my own Papers on Electro-magnetic Rotations in the Quarterly Journal of Science, 1822. xii. 74. 186. 283. 416, and also to my Letter on Magneto-electric Induction in the Annales de Chimie, li. p. 404. These might, as to the matter, very properly have appeared in this volume, but they would have interfered with it as a simple reprint of the "Experimental Researches" of the Philosophical Transactions.

Then I wish to refer, in relation to the Fourth Series on a new law of Electric Conduction, to Franklin's experiments on the non-conduction of ice, which have been very properly separated and set forth by Professor Bache (Journal of the Franklin Institute, 1836. xvii. 183.). These, which I did not at all remember as to the extent of the effect, though they in no way anticipate the expression of the law I state as to the general effect of liquefaction on electrolytes, still should never be forgotten when speaking of that law as applicable to the case of water.

There are two papers which I am anxious to refer to, as corrections or criticisms of parts of the Experimental Researches. The first of these is one by Jacobi (Philosophical Magazine, 1838. xiii. 401.), relative to the possible production of a spark on completing the junction of the two metals of a single pair of plates (915.). It is an excellent paper, and though I have not repeated the experiments, the description of them convinces me that I must have been in error. The second is by that excellent philosopher, Marianini (Memoria della Societa Italiana di Modena, xxi. 205), and is a critical and experimental examination of Series viii, and of the question whether metallic contact is or is not productive of a part of the electricity of the voltaic pile. I see no reason as yet to alter the opinion I have given; but the paper is so very valuable, comes to the question so directly, and the point itself is of such great importance, that I intend at the first opportunity renewing the inquiry, and, if I can, rendering the proofs either on the one side or the other undeniable to all.

Other parts of these researches have received the honour of critical attention from various philosophers, to all of whom I am obliged, and some of whose corrections I have acknowledged in the foot notes. There are, no doubt, occasions on which I have not felt the force of the remarks, but time and the progress of science will best settle such cases; and, although I cannot honestly say that I wish to be found in error, yet I do fervently hope that the progress of science in the hands of its many zealous present cultivators will be such, as by giving us new and other developments, and laws more and more general in their applications, will even make me think that what is written and illustrated in these experimental researches, belongs to the by-gone parts of science.

MICHAEL FARADAY.

Royal Institution, March, 1839.

CONTENTS.

Par. Series I. §. 1. Induction of electric currents 6 §. 2. Evolution of electricity from magnetism 27 §. 3. New electrical state or condition of matter 60 §. 4. Explication of Arago's magnetic phenomena 81 Series II. §. 5. Terrestrial magneto-electric induction 140 §. 6. Force and direction of magneto-electric induction generally 193 Series III. §. 7. Identity of electricities from different sources 265 ---- ---- i Voltaic electricity 268 ---- ---- ii Ordinary electricity 284 ---- ---- iii Magneto-electricity 343 ---- ---- iv Thermo-electricity 349 ---- ---- v Animal electricity 351 §. 8. Relation by measure of common and voltaic electricity 361 ---- Note respecting Ampère's inductive results after 379 Series IV. §. 9. New law of electric conduction 380 §. 10. On conducting power generally 418 Series V. §. 11. Electro-chemical decomposition 450 ---- ¶ 1. New conditions of electro-chemical decomposition 453 ---- ¶ 2. Influence of water in such decomposition 472 ---- ¶ 3. Theory of electro-chemical decomposition 477 Series VI. §. 12. Power of platina, &c. to induce combination 564 Series VII. §. 11.* Electro-chemical decomposition continued (nomenclature) 661 ---- ¶ 4. Some general conditions of Electro-chemical decomposition 669 ---- ¶ 5. Volta-electrometer 704 ---- ¶ 6. Primary and secondary results 742 ---- ¶ 7. Definite nature and extent of electro-chemical forces 783 ---- ---- Electro-chemical equivalents 822 §. 13. Absolute quantity of Electricity in the molecules of matter 852 Series VIII. §. 14. Electricity of the voltaic pile 875 ---- ¶ 1. Simple voltaic circles 875 ---- ¶ 2. Electrolytic intensity 966 ---- ¶ 3. Associated voltaic circles; or battery 989 ---- ¶ 4. Resistance of an electrolyte to decomposition 1007 ---- ¶ 5. General remarks on the active battery 1034 Series IX. §. 15. Induction of a current on itself 1048 ---- Inductive action of currents generally 1101 Series X. §. 16. Improved voltaic battery 1119 §. 17. Practical results with the voltaic battery 1136 Series XI. §. 18. On static induction 1161 ---- ¶ 1. Induction an action of contiguous particles 1161 ---- ¶ 2. Absolute charge of matter 1169 ---- ¶ 3. Electrometer and inductive apparatus 1179 ---- ¶ 4. Induction in curved lines 1215 ---- ---- Conduction by glass, lac, sulphur, &c. 1283 ---- ¶ 5. Specific inductive capacity 1252 ---- ¶ 6. General results as to the nature of induction 1295 ---- ---- Differential inductometer 1307 Series XII. ---- ¶ 7. Conduction or conductive discharge 1320 ---- ¶ 8. Electrolytic discharge 1343 ---- ¶ 9. Disruptive discharge 1359 ---- ---- ---- Insulation 1362 ---- ---- ---- as spark 1406 ---- ---- ---- as brush 1425 ---- ---- ---- positive and negative 1465 Series XIII. ---- ---- ---- as glow 1526 ---- ---- ---- dark 1544 ---- ¶ 10. Convection; or carrying discharge 1562 ---- ¶ 11. Relation of a vacuum to electrical phenomena 1613 §. 19. Nature of the electric current 1617 ---- ---- its transverse forces 1653 Series XIV. §. 20. Nature of the electric force or forces 1667 §. 21. Relation of the electric and magnetic forces 1709 §. 22. Note on electrical excitation 1737 Index Notes

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