Chapter XXVIII: Part II: pp. 254–256, 279, for some of his other correspondence (5)

The subject of the eighth and last section of Reinhold’s Dissertations, as Wilkinson expresses it, consists of the exposition of the hypotheses of different authors on the galvanic fluid. These hypotheses he brings into two classes, as they relate to the seat which is assigned to the cause of the phenomena. The first of these classes belongs to the animal which is to be galvanized, and the second to the substance applied to its body, or to the arc. As the galvanic phenomena are ascribed by several physiologists to electricity, Reinhold makes a new division, relatively to the opinion of those who assert that the galvanic and electric fluids are the same, and of those who are persuaded that the former differs from the latter. Under the first head or division he ranges Galvani, Aldini, Valli, Carradori, Volta, in the early time of the discovery; then Schmuck, Voigt, and Hufeland; while under the second come Fowler and Humboldt. Of the latter division he makes subdivisions, in the first of which he comprehends Volta, Pfaff, Wells, Yelin and Monro, the second embracing Creve and Fabbroni. The other authors, not having openly avowed their opinion, he passes over in silence.

Reinhold is likewise the author of “Versuche um die eigentliche,” etc. (Gilb. “Annal.,” X, 1802, pp. 301–355), “Untersuchungen über die natur.,” etc. (Gilb. “Annal.,” X, 1802, pp. 450–481, and XII, 1803, pp. 34–48); “Galvanisch-elektrische Versuche,” etc. (Gilb. “Annal.,” XI, 1802, pp. 375–387); “Geschichte des Galvanismus,” Leipzig, 1803; “Versuch einer skizzirten,” etc. (Reil. “Archiv.,” VIII, 1807–1808, pp. 305–354); “Ueber Davy’s Versuche” (Gilb. “Annal.,” XXVIII, 1808, pp. 484–485).

REFERENCES.--Schlegel, “De Galvanismo”; Figuier, “Exp. et Hist.
des Principales Découvertes,” Vol. IV. pp. 310, 433; J. W.
Ritter, “Beweis ... in dem Thierreich ...” Weimar, 1796; G. R.
Treviranus, “Einfluss ... thier, Reizbarkeit,” Leipzig, 1801,
and Gilbert’s “Annalen,” Vol. VIII for the latter year.

=A.D. 1798.=--Perkins (Benjamin D.), is given an English patent for a process enabling him to cure aches, pains and diseases in the human body by drawing electrified metals over the parts affected. His metallic tractors, originally introduced from America and consisting of an alloy of different metals, awakened much curiosity both in England and on the Continent, and were successfully used by Dr. Haygarth and others, as related in the article “Somnambulism,” of the “Encyclopædia Britannica.”

In the Repert. II. ii. 179, it is said that one of the tractors was made of zinc, copper and gold, and the other of iron, platina and silver. M. V. Burq, in his “Métallo-thérapie,” makes a review of the successful cures of nervous complaints effected by metallic applications.

REFERENCES.--_Jour. de Phys._, Vol. XLIX. p. 232; Mr.
Langworthy, “View of the Perkinian Electricity,” 1798; T. G.
Fessenden, “Poetical petition against ... the Perkinistic
Institution ...” London, 1803; B. D. Perkins, “The Influence
of Metallic Tractors on the Human Body ...” London, 1798–1799;
“Bibl. Britan.,” Vol. XXI, 1802, pp. 49–89; “Recherches sur le
Perkinisme,” etc. (“Annales de la Soc. de Méd. de Montpellier,”
Vol. XXIX. p. 274); “Sur les tracteurs de Perkins” (“Mém. des
Soc. Savantes et Lit.,” Vol. II. p. 237); P. Sue, aîné, “Hist.
du Galv.,” IV. p. 286 and “Hist du Perkinisme,” Paris, 1805; J.
D. Reuss, “De re electrica,” Vol. XII. p. 20; J. Krziwaneck, “De
electricitate ...” Prag., 1839.

=A.D. 1798.=--In a long letter written to Thomas Jefferson, President of the American Philosophical Society, and read before the latter body on the 4th of May 1798, the Rev. James Madison, then President of William and Mary College, details several experiments made by him to ascertain the effect of a magnet upon the Torricellian vacuum, and to explain the phenomena exhibited by magnets in proximity to iron filings.

He says: “Many ingenious men have supposed that the arrangement of the filings clearly indicated the passage of a magnetic fluid or effluvia in curved lines from one pole to another of a different denomination,” but that the experiments which he relates prove the attractive force of the magnets, at either pole, to be the real cause of the phenomena which the filings exhibit, and that the action of the magnet upon the filings, when they approach within a certain distance, renders them magnetic. In every magnet, says he, there is at least one line, called the equator, from which, in the direction of both poles, the attractive power increases so that the filings will “incline toward them, forming angles which appear to be such as the resolution of two forces, one lateral and the other polar, would necessarily produce.”

Thomas Jefferson, above named, succeeded Benjamin Franklin as United States Minister Plenipotentiary to Paris, 1784–1789, became Vice-President of the United States in 1796, and was sworn in as the successor of John Adams to the Presidency on the 4th of March 1801. The Rev. James Madison, D.D., second cousin of the fourth President of the United States bearing the same name, became President of William and Mary College in 1777, and was consecrated first Bishop of Virginia by the Archbishop of Canterbury in Lambeth Palace, Sept. 19, 1790.

REFERENCES.--“Transactions of the Am. Phil. Soc.,” Vol. IV for
1799, O.S. No. 39, pp. 323–328.

=A.D. 1798.=--Monge (Gaspar), Comte de Peluse, a very able French scientist, called “the inventor of descriptive geometry,” and from whom, it is said, that science received greater accessions than had before been given it since the days of Euclid and Archimedes, erects a telegraph upon the “Palais des Tuileries” in Paris. Of this, however, no reliable details are on record.

He also makes many experiments on the effects of optics and electricity, and, likewise, many useful observations on the production of water by inflammable air, independently of those carried on by Lord Cavendish.

REFERENCES.--Biography in Charles Dupin’s “Essai Historique,”
etc., and in “English Cycl.,” Vol. IV. pp. 296, 297; Memoir at
p. 175 of Vol. LV, _Phil. Mag._ for 1820; G. Monge, “Sur l’effet
des étincelles ...” Paris, 1786, and “Précis des leçons,” Paris,
1805; _Sci. Am. Supp._, No. 621, p. 9916, and the note at foot
of p. 701 of “Fifth Dissert.” eighth ed. of “Encyclopædia
Britannica,” Vol. I; as well as “Mém. de l’Acad. des Sciences,”
1786.

=A.D. 1798.=--Berton (Henri Montan), a prominent French composer and Professor of Harmony at the Paris “Conservatoire de Musique,” also a member of the “Académie des Beaux-Arts,” devises a novel electric telegraph which is merely alluded to, under the heading of “Note historique sur le télégraphe électrique,” at p. 80 of the seventh volume of the _Comptes Rendus_ for July 1838, as well as in Julia Fontenelle’s “Manuel de l’électricité.”

=A.D. 1799.=--Fabbroni--Fabroni--(Giovanni Valentino M.), Professor of Chemistry at Florence, communicates to the _Journal de Physique_ (9th series, Tome VI, Cahier de Brumaire, An. VIII), an amplification of his able memoir, “Sur l’action chimique,” etc. (“Dell’azione chimica ...”), which was first presented by him during 1792 to the Florentine Academy and duly analyzed by Brugnatelli in his “Giornale physico-medico.” Therein is made the first known suggestion as to the chemical origin of voltaic electricity, inquiring whether the phenomenon of galvanism is not solely due to chemical affinities of which electricity may be one of the concomitant effects, and also ascribing the violent convulsions in a frog to a chemical change which is produced by the contact of one of the metals with some liquid matter on the animal’s body, the latter decomposing and allowing its oxygen to combine with the metal.

REFERENCES.--“Elogio ... A. Lombardi” (“Mem. Soc. Ital.,” Vol.
XX); _Cornhill Magazine_, Vol. II for 1860, p. 68; “Biog.
Univ.,” Vol. XIII. p. 311; “Encycl. Met.,” “Galvanism,”
Vol. IV. p. 215; _Journal de Physique_, Vol. XLIX. p. 348;
“Chambers’ Ency.,” 1868, Vol. IV. p. 593; “Mem. Soc. Ital.,”
Vol. XX. pp. 1 and 26; P. Sue, aîné, “Histoire du Galvanisme,”
Paris, An. X-1802, Vol. I. pp. 229–232; _Phil. Mag._, Vol.
V. p. 270; _Nicholson’s Journal_, quarto, Vol. IV. p. 120;
Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 49;
Young’s “Lectures,” Vol. I. p. 752; W. Sturgeon, “Scientific
Researches,” Bury, 1850, p. 156; “Giornale di fisica” for 1810;
“Giornale dell’ Ital. Lettera ...” IX. p. 97; “Atti della Reg.
Soc. Economica di Firenze,” XX. p. 26; Brugnatelli, _Annali
di chimica_, II. p. 316 and XXI. p. 277; C. Henri Boissier,
“Mémoire sur la décomp. de l’eau, etc.,” Paris, 1801 (_Journal
de Physique_, Prairial, An. IX).

=A.D. 1799.=--Jadelot (J. F. N.), French physician, translates Humboldt’s work on “Galvanism,” wherein he reviews the investigations of the great German scientist and treats of the application of the Galvanic fluid in medical practice. The observations of a friend of Humboldt, Dr. C. J. C. Grapengieser, are especially detailed and a complete account is given of all the noted physicians who have recorded experiments in the same line.

REFERENCES.--For the medical applications of Galvanism: _Journal
de Physique_, Vol. LII. pp. 391, 467; Gilbert’s “Annalen,” XI.
354, 488 and XII. 230, 450; “An. of Sc. Disc.” for 1865, p. 123;
Larrey, 1793, 1840; L. Desmortiers, 1801; Legrave, 1803; F. J.
Double, 1803; J. Nauche, 1803; “Galv. Soc.” (_Phil. Mag._, Vol.
XV. p. 281); Laverine, 1803; Mongiardini and Lando, 1803; F.
Rossi, 1803–1827; J. Schaub, 1802–1805; B. Burkhardt, 1802; M.
Butet, 1801; J. Le Roy d’Etiolle, “Sur l’emploi du Galv....”;
P. L. Geiger, 1802–1803; J. D. Reuss in “De Re Electrica”; M.
Buccio, 1812; La Beaume, 1820–1848; P. A. Castberg (Sue, “Hist.
du Galv.,” IV. 264); Fabré-Palaprat and La Beaume, 1828; Rafn’s
“Nyt. Bibl.,” IV; C. C. Person, 1830–1853; S. G. Marianini,
1841; C. Usiglio, 1844; F. Hollick, 1847; G. Stambio, 1847; Du
Fresnel, 1847; H. de Lacy, 1849; M. Récamier, J. Massé, 1851;
R. M. Lawrance, Robt. Barnes, and Crimotel de Tolloy, 1853; M.
Middeldorpf, 1854; R. Remak, 1856, 1860, 1865; J. Seiler, 1860;
V. Von Bruns, 1870.

=A.D. 1799.=--Humboldt (Friedrich Heinrich Alexander, Baron Von) (1769–1859), native of Berlin, is the author of “Cosmos” so frequently alluded to in these pages, and, in the words of one of his biographers, “will be remembered in future times as perhaps, all in all, the greatest descriptive naturalist of his age, the man whose observations have been most numerous and of the widest range, and the creator of several new branches of natural sciences.”

The French translation of his work on “Galvanism” (“Expériences sur le Galvanisme ... traduit de l’allemand par J. F. N. Jadelot”) appeared in Paris during the year 1799, before which date, Noad remarks, no one had applied the galvanic arc, as he did, to so many animals in various parts of their bodies. Among other results, he discovered the action of the electric current upon the pulsation of the heart, the secretions from wounds, etc., and he proved upon himself that its action was not limited to the sole instants of the commencement and end of its passage.

In the first volume of his very interesting work on “Galvanism” (pp. 166–174, 261–310, 407–434) Wilkinson reviews the above-named publication which M. Vassalli-Eandi, in 1799, pronounced “the most complete that has hitherto appeared.” The following sectional extracts are mainly taken from Mr. Wilkinson’s book, Chap. IX. part ii. Humboldt’s first experiments were made with the aid of M. Venturi, Professor of Natural Philosophy at Modena, and they were followed quite assiduously for a while, but it was not until he learned of the important observations made by Fowler, Hunter and Pfaff on animal electricity and irritability, that he was spurred on to still further extended investigations, which were carried on more particularly in presence of Jurine, Pictet, Scarpa, Tralles and Volta. Humboldt’s work is divided into ten sections, as follows:

Sect. I treats of the relation between galvanic irritation and incitability.

Sect. II deals with the galvanic irritation produced without a coating, or metallic or charcoal substances (repeating the investigations of M. Cotugno, which led to the experiments of Vassalli during 1789).

Sect. III treats of the excitement produced by a simple metallic substance, or by homogeneous metallic parts (detailing the experiments of Aldini, Galvani, Berlinghieri, Lind, Pfaff and Volta).

Sect. IV discourses on heterogeneous metals. During his experiments in this line, which were aided by his elder brother, chance led him to a very interesting discovery. He found that the coatings of the nerve and muscle being homogeneous, the contractions may be produced when the degree of excitability is extremely feeble, provided the coatings of this nature are united by exciting substances, among which there is a heterogeneous one, having one of its surfaces covered by a fluid in a state of vapour. This observation, which was originally made at the commencement of 1796, surprised Humboldt so much that he instantly communicated it to Sömmering, Blumenbach, Hertz and Goethe. He had not as yet found recorded in the published works on galvanism any experiment the result of which had the smallest analogy with his discovery; and it was not until after the publication of the works of Pfaff on animal electricity that he became acquainted with any one similar to his own. There were, however, some differences, as he proves by several passages cited from the above author.

Sect. V relates to the classification of active substances into _exciters_ and _conductors_ of the galvanic fluid.

Sect. VI treats of experiments on the comparative effects of animal and vegetable substances employed in the galvanic chain.

Sect. VII describes, in a tabular form, the conducting substances, and those by which the galvanic fluid is insulated. In the employment of very long conductors, it was not possible for Humboldt to remark any interval between the instant when the muscle contracts and the moment the contact of the conductor takes place, the muscle and nerve being from two hundred to three hundred feet distant from each other. This announces a celerity of twelve hundred feet per second. The effect would be the same, should the conductors even be from ten thousand to twenty thousand feet in length. Thus Haller, in his physiology, ascribes to the nervous fluid a swiftness sufficient to enable it to run over a space of nine thousand feet a second. The calculation of Sauvages is carried to thirty-two thousand four hundred feet in the same space of time; and what is still infinitely more surprising, its celerity is estimated by the author of the essays on the mechanism of the muscles at five hundred and seventy-six millions of feet (upward of one hundred thousand miles) in the above space of a second of time. It ought here to be noticed that the great differences in these calculations arise from the different kinds of experiments on which they are founded.

Sect. VIII proves that the nerve which is intended to excite contractions in a muscle should be organically united with it, and it deals with the effects of galvanism upon vegetables, aquatic worms, insects and fishes.

Sect. IX describes the effects of galvanism upon amphibious animals, referring to the observations of Nollet, Rosel, Haller, Spallanzani, P. Michaelis and Herembstads.

Sect. X treats of the all-important effects of galvanism upon man, and makes allusion to the experiments of Hunter, Pfaff, Fowler, Munro, Robison, Hecker, Carradori, Achard, Grapengieser, Schmuck, Ludwig, Creve, Webster and Volta. In speaking of the observations made by the last named upon the tongue, he observes that some idea of them had been given thirty years before, in Sulzer’s work entitled “The New Theory of Pleasures,” published in 1767; and that if, at the above period, the consideration of the superficial situation of the nerves of the tongue had led to the artificial discovery of a nerve, the important discovery of metallic irritation would have been made in the time of Haller, Franklin, Trembley, Camper, and Buffon. How great a progress would not this revelation have made if the above philosophers had transmitted to us, thirty years ago, the theory and experiments which we leave to our successors?

Volta having singled out the differences, in point of savour, which result from galvanic experiments on the tongue according to the nature and disposition of the coatings, Humboldt repeated these experiments and added to them several of his own, with a nearly similar result. His different trials, however, having failed to produce any contraction of the tongue, appear to have established the truth of the ancient assertion of Galen, confirmed by Scarpa, namely, that the nerve with which the tongue is supplied by the third branch of the fifth pair is exclusively devoted to the sense of tasting, and that the ninth pair are exclusively destined for the motion of the tongue. This has been evidently proved by the galvanic experiments on the nerve in question.

The termination, in the pituitous membrane, of the nerves belonging to the organ of smelling, which originate in the first pair and in the first two branches of the fifth, together with the observation of the innumerable phenomena of sympathy between the organs of sight and those of smell and taste, had led to a presumption that, by galvanizing the nostrils, the smell would be affected. This supposition has not, however, been confirmed by any experiment.

The eleventh chapter of Wilkinson’s work contains the analysis of the report drawn up by Mr. J. N. Hallé in behalf of the commission appointed by the French National Institute. This commission, which was organized to look into (_examiner et vérifier_) the different galvanic experiments which had been made and to ascertain their effects and results, was composed of such distinguished French physiologists as Coulomb, Fourcroy, Vauquelin, Charles, Sabathier, Hallé, Pelletan and Guyton de Morveau, who were afterward joined by both Humboldt and the celebrated Prof. Venturi, of Modena.

Humboldt’s observations respecting the application of galvanism to medicine are embodied in his well-known letter to M. Loder, inserted in “La Bibliothèque Germanique,” Vol. IV, Messidor, An. VIII. p. 301, and are likewise detailed by Wilkinson (Chap. XIII) where references are made, more particularly, to the experiments of Hufeland, Behrends, Creve, Hymly, Pfaff and Anschell.

Between the years 1799 and 1804 Von Humboldt made observations upon the magnetic intensity of the earth, of which an account will be found in Vol. XV of the _Annalen der Physik_. These were made upon the American Continent during the course of his well-known journey, the equal of which latter, says Petersen, has not been seen since the days when Alexander the Great fitted out an extensive scientific expedition for Aristotle.

Humboldt’s observations in the same line were continued for many years, notably between 1805 and 1806, in company with Gay-Lussac during a tour which they made together through France, Switzerland, Italy and Germany, as related in the first volume of the _Mémoires de la Société d’Arcueil_.

Some idea can be formed of the extent of Humboldt’s share in the magnetical labours of the first half of the century by perusing the last chapters of his “Cosmos” and the third volume of his “Relation Historique.” At p. 615 of the last-named work, he himself says: “The observations on the variation of terrestrial magnetism, to which I have devoted myself for thirty-two years, by means of instruments which admit of comparison with one another, in America, Europe and Asia, embrace an area extending over 188 degrees of longitude from the frontier of Chinese Dzoungarie to the West of the South Sea, bathing the coasts of Mexico and Peru, and reaching from 60 degrees North latitude to 12 degrees South latitude. I regard the discovery of the law of the decrement of magnetic force from the pole to the equator as the most important result of my American voyage.”

Humboldt was the first who made especial observations of those irregular perturbations to which he applied the name of “magnetic-storms,” and the effects of which he originally observed at Berlin in 1806. These are treated of in his “Cosmos,” London, 1858, Vol. V. pp. 135, etc., wherein he states that, when the ordinary horary movement of the needle is interrupted by a magnetic-storm, the perturbation manifests itself often simultaneously, in the strictest sense of the word, over land and sea, covering hundreds and thousands of miles, or propagates itself gradually, in short intervals of time, in every direction over the earth’s surface. In this same work (“Cosmos,” Sabine’s translation, Vol. I. p. 180), he contributes a graphic description of the concurrent and successive phases of a complete aurora borealis, reference to which is made by Noad (“Manual,” etc., pp. 228, 229, 235), who, likewise, gives (pp. 612–615) an account of the establishment of magnetic stations at different points, for simultaneous observations, upon a plan originally laid out by Humboldt.

As early as 1806, this great naturalist had published at Erfurt his “Inquiry Concerning Electrical Fishes.” While at Naples with Gay-Lussac, during the previous year, they had examined the properties of the _torpedo_, and had observed more particularly that the animal must be irritated previous to the shock, preceding which latter a convulsive movement of the pectoral fins is noticeable, and that electrical action is prevented by the least injury done to the brain of the fish; also, that a person accustomed to electrical discharges could with difficulty support the shock of a vigorous torpedo only fourteen inches long; that the discharge can be felt with a single finger placed upon the electrical organs, and that an insulated person will not receive the shock if the fish is touched with a key or other conducting body (_Phil. Mag._, Vol. XXII. p. 356; _Annales de Chimie_, No. 166; “Encycl. Brit.,” 1855, Vol. VIII. p. 573). Humboldt’s account of the mode of capturing gymnoti is detailed at pp. 575, 576 of the last-named work, as well as at pp. 472–474 of Noad’s “Manual of Electricity,” London, 1859.

At request of the King of Prussia, Humboldt returned from Paris to his native city in 1827, and it was during the winter of 1827–1828 that he began in Berlin his lectures on “Cosmos, or Physical Universe.” This is the title of his chief work, which has universally been recognized one of the greatest productions ever published, and one which Ritter pronounced as being the culminating point both in the history of science and in the annals of civilization.

REFERENCES.--Klenke, “Alex. Von Humboldt, ein biographisches
Denkmal,” 1851: “Alex. Von Humboldt ... von Wittwer,” Leipzig,
1861; “Life of Alex. Von Humboldt,” translated by J. and C.
Lassell, 2 Vols., London, 1873; “Meyer’s Konversations-Lexikon,”
Leipzig und Wien, 1895, Vol. IX. pp. 44–47; Delambre’s
eulogium on Humboldt will be found at p. 15, Vol. XV of
“Edinburgh Review”; Gren’s “Neues Journal der Physik,” Vol.
IV; _Annales de Chimie_, Vol. XXII; _An. Chim. et Physique_,
Vol. XI; Poggendorff’s “Annalen,” Vols. XV, XXXVII; “Société
Philomathique,” Tome I. p. 92; “Opus. Scelti,” XXI. p. 126;
Knight’s “Mech. Dict.,” Vol. II. p. 1874; _Phil. Mag._, Vol. VI
(1800), pp. 246, 250; “Cat. of Sc. Papers of Roy. Soc.,” Vol.
III. pp. 462–467; Vol. VI. p. 692; Vol. VII. pp. 1035–1036;
_Sc. Am. Supp._, No. 457, pp. 7301, 7302; Noad, “Manual,” pp.
425, 528, 529, 612; Harris, “Rudim. Magn.,” Part III. p. 103;
Walker, “Ter. and Cos. Magn.,” 1866, p. 81; Humboldt, “Aphorismi
ex doctrina ...” 1793; “Voyage, etc., dans les années,
1799–1804”; “Report of Seventh Meeting of British Association,”
Vol. VI, London, 1838, pp. 1, 5 and 7, and the remainder of
Major Sabine’s able article upon “Magnetic Intensity,” in the
same volume; “Report of the Meeting of the French Academy of
Sciences” of May 21, 1849, for extract of a letter from Emile
H. Du Bois-Reymond, sent by Humboldt, and treating of the
Electricity of the Human Frame (“L’Institut,” Mai 23, 1849);
S. H. Christie and Sir G. B. Airy, “Report upon a Letter ...”
London, 1836; C. H. Pfaff, “Mém. sur les expér. de Humboldt ...”
1799; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp. 168,
1580–1581.

=A.D. 1800.=--William Nicholson, editor of the journal bearing his name, as well as an able chemist, and Sir Anthony (then Mr.) Carlisle, an English surgeon, while carrying on a series of chemical experiments, discover that, by means of the voltaic pile, water is decomposed into its constituents of oxygen and hydrogen. Their pile consisted of seventeen silver half-crown pieces alternated with equal discs of copper and cloth soaked in a weak solution of ordinary salt, and, having used a little water to make good the contact of the conducting wire with a plate to which the electricity was to be transmitted, Carlisle observed that gas was being set free in the water, while Nicholson recognized the odour of hydrogen proceeding from it. The better to observe this result they afterward (May 2, 1800) employed a small glass tube, which, after being filled with water, was stopped at both ends with corks through which passed two brass wires extending a little distance into the water. When platinum wires were used, gas bubbles appeared from both wires, and the two gases, hydrogen from the negative and oxygen from the positive end, were found to be nearly in the proportion to constitute water. (See account of above in Pepper’s “Electricity,” p. 312, as well as at pp. 193 and 194 of Fahie’s “History of Telegraphy to 1837,” and at pp. 339 and 340 of Vol. I of Lardner’s “Lectures.”)

During the year 1781 William Nicholson had published the first edition of “An Introduction to Natural Philosophy.” In the second section of the third book of the latter work he treats of magnetism, the methods of communicating it, and the variation of the compass. The loadstone, he says, “is a ponderous ore of iron, usually of a dirty black colour and hard enough to emit sparks with steel. It is found in most parts of the world, and possesses a natural magnetism acquired most probably from its situation or position with respect to the earth.” In the third section of the same third book he discourses upon electrical matter, electrical jars, electrical instruments, and devotes much space to the explanation of experiments and facts touching natural and atmospheric electricity, balls of fire, of the _ignis fatuus_, or _will-with-the-wisp_, of waterspouts, earthquakes, etc., alluding to most of the then well-known observations thereon recorded by different scientists.

To Nicholson is due the invention of a revolving doubler, an improvement upon that of Abraham Bennet, which is described and illustrated in the “Encyclopædia Britannica,” as well as in No. 647, p. 10327, of the _Sci. Am. Supplement_ (Read at A.D. 1794, also _Phil. Trans._, Vol. LXXVIII. p. 1, for M. Cavallo’s remarks upon the defects in Bennet’s doubler).

The above-named discovery of Nicholson and Carlisle, which, Mr. Davy says (_Phil. Trans._ for 1826, p. 386) was the true origin of all that had been previously done in electro-chemical science, together with Hisinger and Berzelius’ decomposition of salts, and the successful decomposition of ammonia, nitric acid, etc., made by the distinguished English chemical philosopher, Dr. William Henry (_Nicholson’s Journal_, Vol. IV. pp. 30, 209, 223 and 245; “Encyclopædia Metropolitana,” Vol. IV. pp. 221 and 611; Hutton’s abridgment of _Phil. Trans._, Vol. X. pp. 505, 599), as well as Davy’s decomposition of the earths and alkalies, creates at the commencement of another century, as we have already observed, an entirely new epoch in the history of chemistry.

REFERENCES.--Nicholson’s letter to the Royal Society, read June
5, 1788, entitled “A description of an instrument which, by
the turning of a winch, produces the two states of electricity
without friction or communication with the earth” (influence or
induction machine!); _Nicholson’s Journal_, 1800, Vol. IV. p.
179; Despretz, “Physique,” 1827, p. 432; _Mechanics’ Magazine_,
Nov. 9, 1839; biography in “English Cyclopedia,” Vol. II. p.
82; Tomlinson, “Cyclopedia of Arts,” etc., 1862, Vol. I. p.
566; “Memoir of Joseph Henry,” 1880, p. 78; Highton, “The
Electric Telegraph,” p. 28; Noad, “Manual,” p. 353; “Encycl.
Brit.,” 1855, Vol. XXI. p. 628; _Phil. Trans._, Vol. LXXIX.
p. 265; _Philosophical Magazine_, Vol. VII. p. 337, and XLV.
p. 396; C. H. Wilkinson, “Elements of Galvanism,” 1804, Vol.
II. pp. 21, 22, 46, 68, 375, etc.; “Bibl. Brit.,” Vol. XIX. p.
274; “Sciences et Arts,” Part I. p. 274, and Part II. p. 339,
for Volta’s answer to Nicholson. For various treatises on,
and methods of, effecting the decomposition of water, consult
Adam W. Von Hauch (_Mons’ Jour. de Chimie_, Vol. I. p. 109);
G. Carradori (_Journal de Physique_, An. XII. p. 20, “Nuova
Scel. d’Op.,” quarto, Vol. I. p. 29, Paris and Milan, 1804);
W. Wilson (_Phil. Mag._, Vol. XXII. p. 260); Cioni e Petrini
(Brugnatelli’s _An. di Chim._, Vol. II. p. 322, 1805); M. Van
Marum’s letter to Nauche (_Jour. du Galvan._, Eleventh Book,
p. 187; _Gilb. Ann._, XI. p. 220); J. C. I. A. Creve, as at
Ronalds’ “Catalogue,” p. 119; “Bibl. Britan.,” An. VIII. vol.
xv. p. 23 and An. IX. vol. xvi. p. 23; J. C. Cuthbertson (_Phil.
Mag._, Vol. XXIV. p. 170, 1806); Jos. Mollet’s Memoirs published
at Aix and Lyons, 1821, 1823, as well as in the Reports of the
Lyons Academy, 1823, 1825, and in the _Comptes Rendus_ for
1823; Mr. Leeson (_Sturgeon’s Annals_, Vol. IV. p. 238, 1839;
Robert Hare, _Trans. Am. Phil. Soc._, N.S., Vol. VI. p. 339; L.
Palmieri and P. Linari-Santi, “Telluro-Elettricismo,” 1844; M.
Merget’s theses, read before the Paris Academy, Aug. 30, 1849;
A. Connel, _Phil. Mag._, 4th Ser., for June 1854, p. 426); Dr.
Edward Ash, “On the action of Metals ... upon water,” in letter
to Humboldt, April 10, 1796.

=A.D. 1800.=--Grout (Jonathan, Jr.), of Belchertown, Mass., takes out, October 24, the first telegraph patent in the United States. It was for a contrivance which he operated between Martha’s Vineyard and Boston, about ninety miles’ distance, from hilltop to hilltop, and which was sighted by telescopes (“Telegraph in America,” J. D. Reid, 1887, p. 5; also “Growth of Industrial Art,” Washington, 1888, p. 55).

=A.D. 1800.=--Cruikshanks (William), of Woolwich, England, confirms Nicholson and Carlisle’s experiments, and, in his further prosecution of them, employs a pile consisting of from forty to a hundred pairs of zinc and silver plates, as well as a tube holding silver terminals or electrodes, in place of the platinum electrodes, which they were first to make use of.

He discovers that hydrogen is always evolved from the silver or copper end of the voltaic pile and oxygen from the other; that, under like circumstances, metals can be “completely revived” from their solutions; that pure oxygen is freed when a wire of non-oxidable metal, like gold, is connected with the zinc plate, and that fluids that contain no oxygen cannot transmit the voltaic current. These results were verified by Lieut. Col. Henry Haldane, whose many observations upon the series of metals best suited to the production of voltaic electricity and their respective powers in connection therewith are related at pp. 242 and 313, Vol. IV of _Nicholson’s Journal_ for Sept. and Oct. 1800.

Cruikshanks was also the first to discover, in 1800, that when passing the electric current through water tinged with lithmus, the wire connected with the zinc end of the pile imparted a red tinge to the fluid contiguous to it, and that by using water coloured with Brazil wood, the wire connected with the silver end of the pile produced a deeper shade of colour in the surrounding fluid, whence it appeared that an acid was formed in the former case, and an alkali in the latter. Fahie, who thus mentions the fact, justly remarks that upon this discovery are dependent the electro-chemical telegraphs proposed by Bakewell, Caselli, Bonelli, D’Arlincourt, Sawyer and others.

Cruikshanks is the inventor of the galvanic trough, an improvement upon the voltaic pile, made by soldering together rectangular plates of zinc and copper, and so arranging them horizontally, in a box of baked wood coated with an insulating substance, as to allow of open spaces which can be filled with a solution of salt and water or with diluted acid, to take the place of the wet plates of cloth, paper or pasteboard. Cruikshanks’ plan was adopted in the construction of the powerful battery of 600 pairs, which Napoleon Bonaparte presented to the Ecole Polytechnique and upon which Gay-Lussac and Thénard made their important experiments during the year 1808. As Noad remarks, it is a very convenient form when sulphate of copper is used, for Dr. Fyfe has shown (_Phil. Mag._, Vol. XI. p. 145) that this exciting agent increases the electro-chemical intensity of the electric current as compared with that evolved by dilute sulphuric acid in the proportion of 72 to 16.

Both the above and Volta’s form of battery were much improved upon by Dr. William Babington (1756–1833), who united the pairs of zinc and copper plates by soldering them at one point, and by attaching them to a strip of wood in such a manner as to allow of the entire line being immersed at will into an earthenware or wooden trough having a corresponding number of cells or partitions. The extraordinarily strong voltaic battery, constructed in 1808 for the Royal Institution of London, by Mr. Eastwick under the direction of Sir Humphry Davy and of John George Children, was built upon this plan. It consisted of 200 separate parts, each part being composed of ten double plates, in all 2000 double plates of zinc and copper with a total surface of 128,000 square inches, and the charge which William H. Pepys was accustomed to give it consisted of a mixture of 1168 parts of water, 108 parts nitrous acid, and 25 parts sulphuric acid.

REFERENCES.--Wilkinson, “Elements of Galvanism,” 1804, Vol. II.
pp. 52–63, 96–99; Pepper, “Electricity,” 1809, pp. 313–315;
Noad, “Manual,” pp. 263, 264; Tomlinson, “Cyclopædia of Arts,”
Vol. I. p. 566; Napier, “Electro-Metallurgy,” 1853, pp. 27,
28; _Nicholson’s Journal_, Vol. IV. pp. 187, 254, 261 and
511; _Sturgeon’s Annals_, Vol. IX. p. 309; Cruikshanks, “Some
Experiments and Observations on Galvanic Electricity,” July
1800; also “Additional Remarks on Galvanic Electricity,”
September 1800.

=A.D. 1801.=--Davy (Humphry), a very eminent English chemical philosopher, whose early studies had been greatly influenced both by Dr. John Tonkin, of Penzance, and by Gregory Watt, son of the celebrated inventor, James Watt, as well as by Mr. Davies Giddy Gilbert, who brought him to the notice of the English Royal Institution, delivers before the latter body, on the 25th of April 1801, his first lecture, wherein he traces the history of galvanism, and describes the different methods of “accumulating” it.

His first communication to the Royal Society was made in June of the same year, and is entitled, “An Account of Some Galvanic Combinations Formed by the Arrangement of Single Metallic Plates and Fluids, Analogous to the New Galvanic Apparatus of Volta.” As his able biographer, Prof. T. James Stewart Traill, M.D., of Edinburgh, remarks, this paper is the first of that series of electro-chemical investigations which have immortalized his name. In all hitherto constructed piles, the series had consisted of not less than two metals, or of one plate of metal, another of charcoal, and some interposed fluid. He showed in this paper that the usual galvanic phenomena might be energetically exhibited by a single metallic plate and two strata of different fluids, or that a battery might be constructed of one metal and two fluids, provided one of the fluids was capable of causing oxidation on one of the surfaces of the metal (“Bakerian Lectures,” London, 1840, pp. 32, etc., and _Phil. Trans._, Vol. XCI. p. 297).

On the 20th of November 1806 was read before the Royal Society Davy’s first Bakerian lecture, “On Some Chemical Agencies of Electricity.” This essay was universally regarded as one of the most valuable contributions thus far made to chemistry, and obtained for Davy the prize founded by Napoleon when First Consul, to be awarded by the French Institute, “à celui, qui par ses expériences et ses découvertes, fera faire a l’électricité et au galvanisme un pas comparable à celui qu’ont fait faire à ces sciences Franklin et Volta” (“Bakerian Lectures,” 1840, p. 56, and notes at p. 349, Vol. I of Dr. Lardner’s “Lectures,” etc., 1859).

Of the French Institute Davy became a member in 1817. Regarding the above-named important paper, given in full at pp. 1–56, of the volume of “Bakerian Lectures,” already referred to, Davy says (_Phil. Trans._ for 1826, p. 389): “Referring to my experiments of 1800, 1801 and 1802, and to a number of new facts, which showed that inflammable substances and oxygen, alkalies and acids, and oxidable and noble metals, were in electrical relations of positive and negative, I drew the conclusion _that the combinations and decompositions by electricity were referable to the law of electrical attractions and repulsions_,” and advanced the hypothesis “_that chemical and electrical attractions were produced by the same cause, acting in the one case on particles; in the other on masses; ... and that the same property, under different modifications, was the cause of all the phenomena exhibited by different voltaic combinations_” (Vol. I. pp. 678–684 of Dr. Thomas Young’s “Course of Lectures,” London, 1807, on “Electricity in Motion,” also Dr. Henry M. Noad’s “Manual,” London, 1859, pp. 362–365).

The second Bakerian lecture, “On some new phenomena of chemical changes produced by electricity, particularly the decomposition of the fixed alkalies, and the exhibition of the new substances which constitute their bases; and on the general nature of alkaline bodies,” was read Nov. 19, 1807. In this he gives an account of the most brilliant of all his discoveries (made during the previous month), proving that the so-called fixed alkalies are merely combinations of oxygen with metals. It has been stated by Dr. John Ayrton Paris that since the days of Newton no such happy and successful instance of philosophical induction has ever been afforded as that by which Davy reached the above-named results (_Phil. Trans._ for 1808, Vol. XCVIII. pp. 1–44). Davy’s observations were fully confirmed by Gay-Lussac, Thénard, Berzelius and Pontin (_Annales de Chimie_, Vol. LXXII. p. 193; Vol. LXXV. pp. 256–291; _Bibl. Brit._ for June 1809, p. 122). Although Davy was less successful in his attempt to decompose the proper earths, he proved that they consist of bases united to oxygen. It was reserved for Friedrich Wöhler, Berzelius and Bussy to exhibit the bases by themselves, and to show that all, excepting silica, are metallic, and capable of uniting with iron.

It is said that the original 500-plate batteries of the Royal Institution were so worn in the course of Davy’s experiments as to be almost unserviceable, and that he suggested to the managers the propriety of starting a subscription for the purchase of a large galvanic battery. This being acted upon during the month of July 1808, he was placed in possession of the battery already alluded to in the Cruikshanks article (A.D. 1800), and which was the most powerful constructed up to that time. “With this battery Davy did not reach any new results of importance; but he was enabled to demonstrate the galvanic phenomena upon a more brilliant scale. Nor was the increased power necessary to carry on successfully the experiments on the decomposition of the alkalies and the earths as was apparently believed by many of those historians of science ... who attributed the author’s brilliant success in electro-chemical research to his supposed extraordinary means, the enormous voltaic batteries of the Royal Institution.” In this connection, the terse notes appearing at foot of pp. 62, 63, 106, 107 of the 1840 edition of the “Bakerian Lectures” will prove interesting reading.

It was with the afore-named galvanic combination that Davy openly made--in 1809–1810, and not in 1813, as has been frequently stated--the first display of the continuous electric arc (John Davy, “Memoirs of the Life of Sir Humphry Davy,” p. 446).

“When the cells of this battery were filled with sixty parts of water mixed with one part of nitric acid and one part of sulphuric acid,” he says, “they afforded a series of brilliant and impressive effects. When pieces of charcoal about an inch long and one-sixth of an inch in diameter were brought near each other (within the thirtieth or fortieth part of an inch), a bright spark was produced, and more than half the volume of the charcoal became ignited to whiteness, and by withdrawing the points from each other a constant discharge took place through the heated air, in a space equal at least to four inches, producing a most brilliant ascending arch of light, broad and conical in form in the middle. When any substance was introduced into this arch, it instantly became ignited; platina melted as readily in it as wax in the flame of a common candle; quartz, the sapphire, magnesia, lime, all entered into fusion; fragments of diamond, and points of charcoal and plumbago, rapidly disappeared, and seemed to evaporate in it, even when the connection was made in a receiver exhausted by the air pump; but there was no evidence of their having previously undergone fusion” (“Elements of Chemical Philosophy,” 1812, p. 154).

Dr. Paris says that Davy had already produced the spark upon a small scale as far back as 1800 (_Nicholson’s Journal_, Vol. III, quarto, p. 150), and we learn, through an article published upon the early experiments with the electric light, the names of others who had likewise noticed the arc at about the same period, while Quetelet informs us that M. Curtet is reported to have observed the light between carbon points during the year 1802 (Curtet’s letter to J. B. Van Mons in the latter’s _Journal de Chimie_, No. VI. p. 272, and in _Journal de Physique_, An. XI. p. 54). The article referred to is as follows:

“Dr. S. P. Thompson has given the following interesting details in regard to this subject: In looking over an old volume of the _Journal de Paris_, I found, under date of the Twenty-second Ventose, An. X (March 12, 1802), this passage, which evidently refers to an exhibition of the electric arc: ‘Citizen (E. G.) Robertson, the inventor of the phantasmagoria (magic lantern), is at present performing some interesting experiments that must doubtless advance our knowledge concerning galvanism. He has just mounted metallic piles to the number of 2500 zinc plates and as many of rosette copper. We shall forthwith speak of his results, as well as of a new experiment that he performed yesterday with two glowing carbons. The first having been placed at the base of a column of 120 zinc and silver elements, and the second communicating with the apex of the pile, they gave at the moment they were united a brilliant spark of an extreme whiteness that was seen by the entire society. Citizen Robertson will repeat the experiment on the 25th.’”

The date generally given for this discovery by Humphry Davy is 1809, but earlier accounts of his experiments are found in Cuthbertson’s “Electricity” (1807), and in several other works.

In the _Phil. Mag._, Vol. IX. p. 219, under date of Feb. 1, 1801, in a memoir by Dr. H. Moyes, of Edinburgh, relative to experiments made with the pile, we find the following passage: “When the column in question had reached the height of its power, its sparks were seen by daylight, even when they were made to jump with a piece of carbon held in the hand.” In the same volume of the _Phil. Mag._, and immediately following Dr. Moyes’ letter to Dr. Garthshore, on experiments with the voltaic pile, will be found an account of similar investigations made in Germany, and communicated by Dr. Frulander, of Berlin.

In the “Journal of the Royal Institution” (1802), Vol. I. p. 106, Davy describes a few experiments made with the pile, and says: “When instead of metals, pieces of well-calcined carbon were employed, the spark was still larger and of a clear white.” On p. 214 he describes and figures an apparatus for taking the galvano-electric spark into fluid and aeriform substances. This apparatus consisted of a glass tube open at the top, and having at the side another tube through which passed a wire that terminated in a carbon. Another wire, likewise terminating in carbon, traversed the bottom, and was cemented in a vertical position.

But all these observations are subsequent to a letter printed in “Nicholson’s Journal” for October 1800, p. 150, entitled “Additional experiments on Galvanic Electricity in a letter to Mr. Nicholson.” The letter is dated Dowry Square, Hotwells, Sept. 22, 1800, and is signed by Humphry Davy, who at this epoch was assistant to Dr. Beddoes at the Philosophical (Pneumatic) Institution of Bristol. It begins thus:

“Sir: The first experimenters in animal electricity remarked the property that well calcined carbon has of conducting ordinary galvanic action. I have found that this substance possesses the same properties as metallic bodies for the production of the spark when it is used for establishing a communication between the extremities of Signor Volta’s pile.”

Among the papers read by Davy before the Royal Society between June 30, 1808, and Feb. 13, 1814, are the following: “Electro-chemical researches on the decomposition of the earths, with observations on the metals obtained from the alkaline earths, and on the amalgam procured from ammonia”; “An account of some new analytical researches on the nature of certain bodies,” etc., and the Bakerian lecture “On some new electro-chemical researches, on various objects, particularly the metallic bodies from the alkalies and earths, and on some combinations of hydrogen”; “Elements of chemical philosophy, detailing experiments on electricity in vegetation.”

In alluding to the important subjects covered by him during the above-named period, his brother and biographer, John Davy, M.D., F.R.S., says: “I shall not attempt an analysis of these papers; I shall give merely a sketch of the most important facts and discoveries which they contain, referring the chemical reader to the original for full satisfaction. After the extraction of metallic bases from the fixed alkalies, analogies of the strongest kind indicated that the alkaline earths are similarly constituted; and he succeeded in proving this in a satisfactory manner. But, owing to various circumstances of peculiar properties, he was not able on his first attempts to obtain the metals of those earths in a tolerably pure and insulated state for the purpose of examination. On his return to the laboratory after his illness, this was one of the first undertakings. He accomplished it to a certain extent by uniting a process of Messrs. Berzelius and Pontin, who were then engaged in the same enquiry, with one of his own. By negatively electrifying the earths, slightly moistened, and mixed with red oxide of mercury, in contact with a globule of mercury, he obtained amalgams of their metallic bases; and, by distillation, with peculiar precautions, he expelled the greater part of the mercury. Even now, in consequence of the very minute quantities of the bases which he procured, and their very powerful attraction for oxygen, he was only able to ascertain a few of their properties in a hasty manner. They were of silvery lustre, solid at ordinary temperatures, fixed at a red heat, and heavier than water. At a high temperature they abstracted oxygen from the glass, and, at ordinary temperatures, from the atmosphere and water, the latter of which in consequence they decomposed. The names he proposed for them, and by which they have since been called, were barium, strontium, calcium and magnium, which latter he afterwards altered to magnesium....”

The reviewer of Davy, in the columns of the “Chemical News,” writing in 1879, states that his papers on numerous subjects flowed into the Royal Society’s archives in an uninterrupted stream, and it may be said, without exaggeration, that his work, especially during the six years from 1806 to 1812, did more for chemistry than the 60 which followed them.

Between the last-named dates, Davy was asked by the Dublin Society to give a course of lectures on electro-chemical science, which he delivered Nov. 8–29, 1810. Trinity College afterward conferred on him the degree of LL.D., and he was knighted by the Prince Regent one day before resigning from the Royal Institution, wherein he gave his farewell address on April 9, 1812.

In 1813, accompanied by his bride and Mr. Faraday (his “assistant in experiments and in writing”), Davy made his first trip to the Continent, where he met Ampère, Humboldt, Gay-Lussac, Vauquelin, Cuvier, Laplace and other distinguished scientists, and where he carried on many experiments, of which the results were duly communicated to the Royal Society, as were also the observations made by him up to the time of the completion of his second trip in 1820.

Besides the Rumford medal conferred on him in 1816, he received a baronetcy two years later, and was given, in 1827, the medal of the Royal Society, the presidential chair of which he occupied for seven consecutive years.

One of the four memoirs produced by Davy in 1818–1829 treats of electro-magnetism. In 1820, Davy, Arago and Seebeck independently discovered the magnetizing power of the electric current on steel and iron needles or filings. In Davy’s experiments, it is said, the filings adhered to the wire connecting the poles of a voltaic apparatus, consisting of a hundred pairs of plates of four inches, in such considerable quantities as to form a mass around it ten or twelve times the thickness of the wire (_Phil. Trans._ for 1821, p. 9; _Annales de Chimie et de Physique_, Vol. XV. p. 93).

Davy was actively engaged during 1821–1822 in experiments on electro-magnetism and on electricity in vacuo, reaching the conclusion, in the last-named channel, that electric light as well as electrical attractions and repulsions are observable in the most perfect vacuum obtainable. This is readily demonstrated with either the apparatus employed by Tyndall in his Lecture VIII, “On the analogies of light, heat and sound,” or with the apparatus used by Davy and illustrated at Plate CCXXIII of the “Encyclopædia Britannica,” eighth edition. From the numerous experiments and observations recorded in the last-named work the following are extracted:

“A spark capable of passing through only half an inch in common air will pass through six inches of the Torricellian vacuum.... When the minutest quantity of rare air was introduced into the mercurial vacuum, the colour of the electric light changed from bright _green_ to _sea green_, and by increasing the quantity, to _blue_ and _purple_. At a low temperature the vacuum became a much better conductor. A vacuum above fused tin exhibited nearly the same phenomena. At temperatures below zero the light was yellow and of the palest phosphorescent kind, just visible in great darkness, and not increased by heat. When the vacuum was formed by pure olive oil and by chloride of antimony, the electric light through the vapour of the chloride was more brilliant than that through the vapour of the oil; and in the last it was more brilliant than in the vapour of mercury at common temperatures. The light was of a _pure white_ with the chloride, and of a _red_ inclining to _purple_ in the oil.... In carbonic acid gas the light of the spark is white and brilliant, and in hydrogen gas it is red and faint. When the sparks are made to pass through balls of wood or ivory they are of a _crimson_ colour. They are _yellow_ when taken over powdered charcoal, _green_ over the surface of silvered leather, and _purple_ from imperfect conductors.”

Davy’s Bakerian lecture for 1826 was entitled “On the relation of electrical and chemical changes.” Two years previous to its reading he had communicated to the English Government his discovery of what he erroneously considered a remedy against the rapid deterioration of copper sheathing for ships. His plan consisted in altering the electrical condition of the copper by adding plates of zinc or iron (called “protectors”), but the bottoms of the vessels became so foul through the deposition of calcareous matter and the adhesion of large balani and lepades, etc., to the copper, that the attempt had to be abandoned (A. Bobierre, “Thèse ... pour doubler les navires,” Nantes, 1858). It was in the same year (1824) that Davy made an important journey through Sweden, Norway, Denmark, Holstein, and Hanover, during which he met Oersted, Berzelius, Gauss, Olbers, Schumacher and other savants.

His last communication to the Royal Society, “Remarks on the Electricity of the _Torpedo_,” was sent from Rome in 1828, one year before his death, and embodies the result of many observations made while on the Continent, more especially during the years 1814–1815. The investigations in this line which, owing to continued ill health, he was unable to carry on, were completed by his brother, Dr. John Davy, who established the following points of difference between the phenomena of the _torpedo_ and those of other kinds of electricity:

“Compared with voltaic electricity, its effect on the multiplier is feeble: its power of decomposing water and metallic solutions is inconsiderable; but its power of giving a shock is great, and so also is its power of magnetizing iron. Compared with common electricity, it has a power of affecting the multiplier, which, under ordinary circumstances, common electricity does not exhibit; its chemical effects are more distinct; its power of magnetizing iron and giving a shock appears very similar; its power of passing through air is infinitely less as is also (if it possess it at all) the power of producing heat and light.”

Davy likewise made noteworthy observations concerning the pyro-electricity of the tourmaline, confirming previous investigations in the same line, and asserting that “when the stone is of considerable size, flashes of light may be seen along its surface” (“Elements of Chemical Philosophy,” Vol. I. p. 130), a curious fact which Sir David Brewster says he does not believe has ever been verified by any subsequent observer.