Chapter XXX: Section V: , treating of “Magnetic Attraction,” concludes as follows (1)

“How far these observations and experiments go to establish the doctrine of a magnetic effluvium flowing through the earth, or from one end of a magnet to the other, must be left to the reader’s judgment and opinion. We are apt to laugh at the _subtil matter_ of Descartes and the _aether_ of Euler, as occult qualities, which modern philosophy will not admit into its creed, but this effluvium is a _subtil_ matter, an _aether_, equally as inexplicable and as equally out of the reach of our five senses to scrutinize; however, if we may venture to guess at causes by effects, and to compare analogies with what we can see, feel, etc., I think we have infinite data in favour of an electro-magnetic fluid, superior to any proof that can be brought of æther being the cause of gravity, light, vision, etc.”

John Read’s letter to the author concerning the _electrophorus_ appears at pp. 47–49 of the second volume (Poggendorff, Vol. II. pp. 1248–1249).

=A.D. 1802.=--Alexandre (Jean), who is said to have been the natural son of Jean Jacques Rousseau, and to have studied for the medical profession, operates his secret telegraph (_télégraphe intime_) at Poitiers, and afterwards addresses M. Chaptal, Ministre de l’Intérieur, asking for financial aid in order that he may be enabled to go to Paris and submit his invention to the French Government. This request being refused on account of Alexandre’s unwillingness to divulge his secret, he next obtained an audience of M. Cochon, Prefect of Vienne, before whom he demonstrated his invention so successfully that the latter was induced to make a report of it to M. Chaptal, advising him to invite Alexandre to Paris at the expense of the State. A second refusal, however, followed, and Alexandre went to Tours, where he there also failed to obtain the desired assistance, after giving successful exhibitions of his telegraph before the Prefect of Indre-et-Loire, General Rommereul, as well as before the Mayor and the city officials.

The substance of Prefect Cochon’s communication is to be found translated at pp. 111–113 of Fahie’s “History of Electric Telegraphy,” which latter also contains a full translation of the report addressed, 10 Fructidor, An. X by the celebrated French astronomer, J. B. J. Delambre, to the First Consul, suggesting for the inventor’s representative, M. Beauvais, an interview which Bonaparte, however, refused to grant.

Alexandre died, 1832–1833, without having revealed his secret to any one but M. Beauvais. It is stated by Fahie that in the English _Chronicle_ of June 19–22, 1802, appears a brief account of the above-named exhibition given at Tours, concluding as follows: “The art or mechanism by which this is effected is unknown, but the inventor says that he can extend it to the distance of four or five leagues, even though a river should be interposed.” A copy of the above-named newspaper, doubtless unique, was in Latimer Clark’s library.

REFERENCES.--“Annales Télégraphiques,” March-April, 1859, pp.
188–199, for M. Edouard Gerspach’s Memoir; “Sci. Am. Suppl.,”
No. 384, for a translation of M. Auguste Guéroult’s article in
“La Lumière Electrique”; M. Cézanne, “Le Cable Transatlantique,”
Paris, 1867, p. 32; M. Bério, “Ephemerides of the Lecture
Society,” Genoa, 1872, p. 645.

=A.D. 1802.=--Sue (Pierre, aîné), a very able French physician, publishes, at Paris, “Histoire du Galvanisme et analyse des différents ouvrages publiés sur cette découverte ...” which is considered by scientists one of the most important works on the subject.

REFERENCES.--“Biographie Générale,” Vol. XLIV. pp. 618–619;
Larousse, “Dictionnaire Universel,” Vol. XIV. p. 1200;
Wilkinson, “Elem. of Galv.,” 1804, Vol. I. p. 182.

=A.D. 1802.=--Brugnatelli (Luigi Valentino), who, after being a pupil, became the close friend and subsequently the colleague of Volta at the Pavia University, is the first to obtain, by means of the voltaic pile, a decidedly practical result in electro-plating. He gilded two large silver medals on bringing them in communication, by means of the steel wire, with the negative pole of a voltaic pile, and by keeping them one after the other immersed in ammoniurets of gold newly prepared and well saturated (_Phil. Mag._ for 1805).

He also electro-deposited bright metallic silver upon platinum, and observed that when the current entered the liquid by means of a pole of copper or zinc, those metals were dissolved and then deposited upon the negative pole. Spon tells us (“Dictionary of Engineering,” London, 1874, Vol. II. p. 1378) that the solutions employed by Brugnatelli were alkaline; they consisted of ammoniurets of gold, silver or platina, that is, the product obtained by treating the chlorides of gold and platina or the azotate of silver, by ammonia. There is much obscurity in the descriptions of Brugnatelli, but according to the _Journal de Physique et Chimie_ of Van Mons, the most expeditious method of reducing, by means of the battery, dissolved metallic oxides, is to make use of their ammoniurets by placing the ends of two conducting wires of platina into ammoniuret of mercury. The wire of the negative pole speedily becomes covered with small particles of this metal. MM. Barral, Chevalier and Henri tried to reproduce Brugnatelli’s operation by following his descriptions, but with very imperfect results, the nature of the dissolvent employed by the learned Italian not being known.

At p. 136, Vol. XVIII of his _Annali di Chimica_, etc., Brugnatelli publishes a memoir entitled “Chemical Observations on the Electric Acid.” He says:

“Naturalists have hitherto merely abandoned one erroneous hypothesis for another, in considering the nature of the electric fluid. Some have regarded it as identical with heat; while others have been led to consider it as a modified caloric. The disciples of Stahl ascribed it to the nature of their _phlogistic_ or, at least, supposed it to be a fluid abundantly provided with that principle. Henley conjectured it to be phlogistic, when in a state of repose, and fire, when in a state of activity. Among the moderns, several have been found who have declared it to be an acid; but their opinion has been combated by Gardini, who, by means of several ingenious observations, has endeavoured to demonstrate that it is composed of caloric and hydrogen.”

In the earlier experiments on the decomposition of even chemically pure water by the voltaic column, the presence of an acid was always apparent at the pole evolving oxygen, while alkaline matter appeared at the other (_Nicholson’s Journal_, quarto, Vol. IV. p. 183).

Mr. William Cruikshanks supposed the former to be the nitrous acid resulting from a combination of the oxygen at the positive pole with the azote of the air held in solution by the water, while the alkali, he said, proceeded from the combination of the same principle with the hydrogen evolved at the negative pole (_Nicholson’s Journal_, quarto, Vol. IV. p. 261). Mr. C. B. Desormes afterward endeavoured to show that the products were ammonia and muriatic acids (_Annales de Chimie_, Vol. XXXVII. p. 233). Brugnatelli’s experiments with the _couronne de tasses_, however, led him to consider it to be an acid _sui generis_ produced by the combination of one of the constituents of water with positive electricity. He classed it as _oxi-electric_, and of all the metals, gold and platina alone appeared to him not to be sensibly affected by this electric acid.

REFERENCES.--For Brugnatelli’s record of other experiments
and observations and for his Memoirs upon different piles,
upon animal electricity, upon the identity of the electric and
galvanic fluids, etc. etc., see his “Principes,” etc., 1803,
and “Grundsätze des Elektricität,” etc., 1812, his _Annali
di Chimica_, Vols. VII. p. 239; XIX. pp. 77, 153, 274, 277,
280–281; XXI. pp. 3, 143, etc., 239; XXII. pp. 1, etc., 77–92,
257, 301; the _Giornale di Chimica, Fis. e Storia Nat._ of
L. and G. Brugnatelli, G. Brunacci and P. Configliachi, Vol.
I. pp. 147–163, 337–353; IX. p. 145; XI. p. 130, and the
“Commentarii Medici,” edited by L. Brugnatelli and L. V. Brera;
also Brugnatelli’s _Giornale Fisico-Medico_, etc., and its
continuation, _Avanzamenti della Medicina e Fisica_, the first
named containing (Vol. I. p. 280), a repetition of Galvani’s
experiments, made by Volta, Rezia and Brugnatelli; G. Bianconi,
“Intorno ...” and “Cenni intorno ... Galvanoplastica” (_Nuovi
Annali della Scienze Naturali_); the “Biblioteca Italiana,” of
which his son Gaspare Brugnatelli was an editor, in conjunction
with Breislak, Configliachi, Carlini, Cotena, Acerbi, Brunacci,
Fantonelli, Fumagelli, Ferrario, Giordiani, Gironi and Monti; G.
A. Giobert, “Gior. Fis. Med.,” 1188; Du Pré, “Ann. di Chimica,”
IX. 156; P. Mascagni, “Lettera ...” for Brugnatelli’s notes; A.
Cossa, “Notizie ... elettro-chimica,” 1858; J. Napier, “Man. of
El. Met.,” 4th ed., pp. 491, 492; J. B. Van Mons’ _Journal de
Chimie_, Vols. I. pp. 1, 24, 101, 216, 325; II. pp. 106, 216;
IV. p. 143; X. p. 114; XVI. p. 132; also Vol. LXXVI; _Giornale
di Fis. Chim._, Vol. I. pp. 4–32, 28, 139–147, 164–166, 338;
“Effemeridi Chim. Mediche di Milano,” 1807, Sem. I. p. 57; A.
F. Gehlen’s _Journal für die Chemie_, Vol. I. pp. 54–88; VI.
pp. 116–124; VIII. pp. 319–359; L. W. Gilbert, _Annalen der
Physik_, Vols. VIII. pp. 284–299; XVI. pp. 89–94; XXIII. pp.
177–219; _Philosophical Magazine_, Vols. XXI. p. 187; XXV.
pp. 57–66, 130–142; LIII. p. 321; Dr. Thos. Thomson’s _Annals
of Philosophy_, Vol. XII. p. 228; Alfred Smee’s “Elements of
Electro-Metallurgy,” _History_, pp. xxv-xxvi; _Journal de
Pharmacie_, Vol. III. pp. 425, 426; J. Nauche, _Journal du
Galvanisme_, etc., Vol. II. pp. 55–60; P. Sue, aîné, “Histoire
du Galvanisme,” An. X, 1802, Vol. I. p. 305; II. pp. 263, 316,
320, 328; _Annales de Chimie_, Feb. 1818; for Brugnatelli,
“Biblioth. Britan.,” Vol. XXXI., 1806, pp. 43, 122, 223 (pile
végétale).

=A.D. 1802.=--Jäger (Karl Christoph Friedrich van), a well-known physicist of Wurtemberg and professor at Stuttgart, confirms by mathematical analysis the theory of electrical distribution and equilibrium, as will be seen by his papers in Gilbert’s _Annalen der Physik_, Vols. XII. pp. 123, 127; XIII. pp. 399–433; XXIII. pp. 59–84, and LII. pp. 81–108.

The views of Jäger were fully endorsed by Berzelius, who, like Scholz and Reinhold, endeavoured to extend them, and who says that we are indebted to the German physicist for actually the most complete elucidation of the theory of the voltaic pile.

In Vol. XLIX of Gilbert’s _Annalen_ for 1815, pp. 47–66, will be found Jäger’s observations and experiments on Zamboni’s column as well as the papers of Zamboni and Deluc on dry piles. Dr. Thomson says that since Dr. Jäger found that, when the temperature was raised to 104 degrees, or as high as 140 degrees, the pile begins again to act as well as ever, we must conclude from this that dry paper, while cold, is a nonconductor of electricity, but that it becomes again a conductor when heated up to 104 degrees or 140 degrees.

REFERENCES.--Poggendorff, Vol. I. pp. 1186, 1187; “Catalogue of
Scientific Papers of the Royal Society,” Vol. III. p. 525; Jäger
on the tourmaline in Gilbert’s _Annalen_ for 1817, Vol. LV. pp.
369, 416, and Jäger, Bohnenberger and Zamboni in the _Annalen_
for 1819, Vol. LXII. pp. 227–246; Figuier, “Expos. et Histoire,”
1857, Vol. IV. p. 433; Davy, “Bakerian Lectures,” 1840, pp.
44–56, on the “Agencies of Electricity.”

=A.D. 1802.=--Gale (T.), an American physician, publishes at Troy “Electricity or Ethereal Fire ... considered naturally, astronomically and medically, and comprehending both the theory and practice of medical electricity,” etc. Among other things, he describes at pp. 27, 28, various experiments made with his galvanometer; explains at pp. 46–64 how the Newtonian principles are erroneous; and shows at p. 264 how to extract lightning from the clouds; while at pp. 272, etc., are given directions for using electricity both as a sure preventive and cure of diseases.

=A.D. 1802.=--Gibbes (George Smith), M.D., of Bath, reads before the Royal Society a paper on the Phenomena of Galvanism thus noticed by Dr. Young at pp. 672, 673, Vol. II. of his “Course of Lectures,” London, 1707:

“Dr. Gibbes begins with reciting some experiments on the oxidation produced during the union of tinfoil with mercury, first in the air and then under water. He assumes a different opinion from that of Dr. Wollaston, respecting the origination of electricity in chemical changes, and maintains on the contrary that the electrical changes are to be considered as preceding and favouring the chemical. He imagines that the simple contact of various substances produces changes of electrical equilibrium, and that the action of acids is effectual in promoting these changes, by bringing their surfaces into contact. Dr. Gibbes observes upon Dr. Wollaston’s experiment of immersing zinc and silver in an acid solution, that if they are placed in two separate portions of the fluid, and the parts not immersed are brought into contact there is no emission of gas from the silver; but that it is copiously produced when the contact takes place in the same fluid. He proceeds to relate some experiments which seem to show a difference between galvanism and electricity, particularly that galvanism does not appear to be attracted by metallic points. He also states an experiment in which a piece of paper is placed on tinfoil, and rubbed with elastic gum, and although the tinfoil is not insulated, sparks are produced on raising the paper. Dr. Gibbes concludes with some arguments against the doctrine of the decomposition of water; and advances as a probable opinion, that oxygen and hydrogen gas are composed of water as a basis, united with two other elements, which, combined, form heat.”

As remarked by Wilkinson (“Elements of Galvanism,” London, 1804, Vol. II. pp. 385, 386), Dr. Gibbes’ hypothesis as to the composition of water having been deduced from Richter’s experiments, and these latter proving erroneous, the ingenious superstructure which the doctor has erected must necessarily fall to the ground.

=A.D. 1802.=--Romagnosi (Gian Domenico Gregorio Giuseppe), Italian jurist of Salsomaggiore, near Piacenza, who had devoted much time to scientific investigation, and was about taking the law professorship at the Parma University, communicates, Aug. 3, 1802, to the _Gazetta di Trento_, his important paper entitled “Articulo sul Galvanismo.” Of the latter, a translation, made from the reprint at p. 8 of Gilb. Govi’s “Romagnosi e l’Elettro-magnetismo,” appears at pp. 259, 260 of Fahie’s “History of Electric Telegraphy.”

To Romagnosi has by many been given the credit of having discovered the directive influence of the galvanic current upon a magnetic needle. This claim has of late years been again made for him, notably by Dr. Donato Tommasi, of Paris (_Cosmos, les Mondes_ of June 30, 1883), while Dr. J. Hamel endeavoured to prove (pp. 37–39 of “Historical Account ... Galv. and Mag. Elec. ...” reprinted by W. F. Cooke for the Society of Arts, London, 1859) that Oersted was aware of Romagnosi’s experiments at the time he published the discovery of electro-magnetism. This is what Dr. Hamel says:

“I cannot forego stating my belief that Oersted knew of Romagnosi’s discovery announced in 1802, which was eighteen years before the publication of his own observations. It was mentioned in the book of Giovanni Aldini (the nephew of Galvani) ... Oersted was in Paris 1802 and 1803, and it appears from the book of Aldini, that at the time he finished it Oersted was still in communication with him; for he says at the end (p. 376) he had not been able to add the information received from Oersted, Doctor of the University at Copenhagen, about the galvanic labours of scientific men in that country.... It deserves to be remembered, that from Aldini’s book (“Essai théorique et expérimental sur le galvanisme,” etc., Paris, 1804, qto. p. 191, or Vol. I. of the 8vo ed., pp. 339–340) it was known that the chemist, Giuseppe Mojon (Joseph Mojon, in the French), at Genoa, had before 1804 observed in unmagnetized needles exposed to the galvanic current ‘a sort of polarity.’ Joseph Izarn repeats this also in his ‘Manuel du Galvanisme’ (Paris, An. xii., 1804, sec. iii. p. 120, or 1805, sec. ix.), which book was one of those that by order were to be placed in the library of every lycée of France.”

Robert Sabine remarks (“The Electric Telegraph,” 8vo., 1867, p. 22; “History of the Electric Telegraph,” in Weale’s Rudimentary Treatises, 1869, pp. 23, 24; “History and Progress of the Electric Telegraph,” 3rd ed., 1872, p. 23):

“The discovery of the power of a galvanic current to deflect a magnetic needle, as well as to polarize an unmagnetized one, were known to, and described as early as 1804, by Prof. Izarn.... The paragraph which especially refers to this subject is headed ‘Appareil pour reconnaitre l’action du galvanisme, sur la polarité d’une aiguille aimantée.’ After explaining the way to prepare the apparatus, which consists simply in putting a freely suspended magnetic needle parallel and close to a straight metallic conductor through which a galvanic current is circulating, he described the effects in the following words: ‘According to the observations of Romagnosi, a physicist of Trent, a magnetized needle which is submitted to a galvanic current undergoes (_éprouve_) a declination; and according to those of J. Mojon, a learned chemist of Genoa, unmagnetized needles acquire by this means a sort of magnetic polarity.’ To Romagnosi, physicist of Trent, therefore, and not, as is generally believed, to Oersted, physicist at Copenhagen (who observed, in 1820, the phenomenon of the deflection of a magnet needle by a voltaic current), is due the credit of having made this important discovery.”

On the other hand, Gilb. Govi, who gives in his afore-named work a good illustration of Romagnosi’s experiment, explains that it resembles in no way the experiment of Oersted, there being no magnetic action of the column on the magnetic needle, which latter is in fact repelled by the mere electricity of the pile. Ronalds states that Romagnosi’s experiment, much like that made by Schweigger (A. F. Gehlen’s _Journal für die Chimie und Physik_, 1808, pp. 206–208), was a modification if not a repetition of the one which Thomas Milner performed with static electricity (T. Milner’s “Experiments and Observations in Electricity,” London, 1783, p. 35), wherein a magnetic needle forms the electrometer since improved upon by J. C. A. Peltier.

To the ordinary mind, a conclusive proof that Romagnosi had no part in the discovery of electro-magnetism would seem to be, as Fahie rightly observes, the fact that he himself never claimed any, although he lived until 1835, fifteen years after the announcement made by the Danish philosopher. Fahie calls attention, for some experiments in the same line, to J. B. Van Mons’ _Journal de Chimie_, Bruxelles, January 1803, p. 52, and to Nicholson’s _Journal of Nat. Phil._, Vol. VII. p. 304, as well as to the 1746 and 1763 _Phil. Trans._ for investigations made by B. Robins and Ebenezer Kinnersley, and he likewise alludes to others recorded in the _Amer. Polytechnic Review_ for 1831, and in the _Quarterly Journal of Science and the Arts_ for 1826, to all of which, he says, as little real attention should be given as can properly be attached to the observations of Aldini and of Izarn previously referred to.

REFERENCES.--“Notizia di G. D. Romagnosi, stesa da Cesare Cantù,” Milan, 1835; “Nuova Scelta d’ Opuscoli,” Vol. I. p. 201; _Gazetta di Roveredo_ for 1802, No. 65; “Atti della Reale Accad. delle Scienze di Torino,” Vol. IV, April 7, 1869; J. C. Poggendorff, Vol. II. pp. 681, 682; S. I. Prime’s “Life of Morse,” 1875, p. 264; _Phil. Mag._, Vol. LVIII. p. 43; _Journal Soc. of Arts_, April 23, 1858, p. 356, and July 29, 1859, pp. 605, 606; _Bibl. Ital._, Vol. XCVIII. p. 60; Gilbert, _Annalen_, 1821, Vol. LXVIII. p. 208; Larousse, “Dict. Univ.,” Vol. XIII. p. 1318; “Biographie Générale,” Vol. XLII. pp. 574, 575, the last named remarking that the discovery alluded to in the works of Aldini and Izarn passed unnoticed till Oersted caused its value to be fully appreciated.

=A.D. 1802.=--Parrot (George Friedrich), Russian physician and professor at Dorpat, is, of all the European savants, the one who developed most extensively the chemical theory of the voltaic pile. The superior manner in which all his observations were carried on have led many to consider him justly entitled to the credit of being the founder of the theory (Figuier, “Exposition et Histoire,” etc., Paris, 1857, Vol. IV. chapitre viii. pp. 426–429).

He commenced his experiments in 1801, and first recorded them in a memoir which was crowned the same year by the Batavi Scientific Society of Haarlem. His other papers on the same subject followed in rapid succession, mainly through L. W. Gilbert’s _Annalen der Physik_, under such heads as: “Sketch of a New Theory of Galvanic Electricity, and Concerning the Decomposition of Water,” etc. (“Combination of Induction and Chemical Action,” Gilb., Vol. XII. p. 49, Seypfer, p. 200), “How to Measure Electricity,” “Relative to the Electrometer,” “The Effects of the Condenser,” and “The Theory of Volta Concerning Galvanic Electricity,” all of which appeared in Vol. LXI. of the _Annalen_. These papers were alluded to in his letter to the editors of the _Annales de Chimie et de Physique_ (_An. Ch. et Phys._, Vol. XLII. p. 45), and were afterward greatly amplified in his “Treatise on Natural Philosophy.”

Parrot started with the determination to demolish completely the theories of Volta and to thoroughly instruct him anew (_instruire de toutes pièces le procès du physicien de Pavie_), and it must be admitted that the many important facts enounced by Parrot were such as would have ordinarily created a disturbing influence, but they became known after Volta’s views had been thoroughly espoused by many German and French scientists and consequently attracted comparatively little attention.

At p. 466, Vol. II of Dr. Thomas Young’s “Course of Lectures,” London, 1807, reference is made to a paper in Gilbert’s _Annalen der Physik_ (X. p. 11, also XIII. p. 244), concerning Parrot’s theory of evaporation, with mention of the fact that the same paper contains a proposal for inoculating the clouds with thunder and lightning, by projecting bombs to a sufficient height.

Parrot also devised a scheme for telegraphing, which is described in the _Mem. Acad. Petropol._, ser. vi. Vol. I for 1838, and is alluded to in the Report on Telegraphs for the United States, made at request of the Hon. Levi Woodbury, Secretary of the Treasury, by the Committee on Science and the Arts of the Franklin Institute. The proposed telegraph, as worded in the Report, “consists of a single arm or _indicator_, which should be about nine feet long and one foot wide, with a cross-piece at one end, about three feet long and one wide; the whole being movable about an axis at its centre.... The movements may be communicated with ease and certainty, either by an endless chain passing over a wheel on the axis, and a wheel in the building; or by a cog-wheel on the axis, and an endless screw on a vertical bar. For night signals, three lamps are used, one swinging beyond the end of the arm, the other two beyond the ends of the cross-piece.”

REFERENCES.--Gilbert’s _Annalen_, Vols. XXI for 1805, LV for
1817, LX for 1819; J. H. Voigt’s _Magazin_, Vol. IV; Grindel’s
“Russ. Jahrb. f. Chem. u. Pharm.,” XI, 1810; L. Turnbull, “Elec.
Mag. Tel.,” p. 19; “Naturwiss. Abhandl. aus Dorpat.,” I, 1823;
“Roy. Soc. Cat. of Sc. Papers,” Vol. IV. pp. 765–767; _Annales
de Chimie_, Vol. XLII, 1829, pp. 42–45, and Vol. XLVI, 1831, p.
361; “Mém. sixième série Sc. Mathém.,” first part of Vols. III
and V; “Pander’s Beitr. z. Naturk, I.”

=A.D. 1802–1806.=--Berzelius (Baron Jöns Jacob Freiherr von), M.D., one of the greatest of modern chemists, native of East Gothland, Sweden, publishes his “De Electricitatis ...” or “Physical Researches on the Effect of Galvanism upon Organized Bodies,” which established his reputation as an experimental philosopher and procured for him the appointment of Assistant Professor of Medicine, Botany and Chemical Pharmacy at Stockholm. Of the very great number of scientific papers which he communicated to learned Societies, that entitled “An Essay on the Division of Salts through Galvanism” deserves especial mention, for in it, he lays down the electro-chemical theory, the honour of being the original propounder of which is by many claimed for Sir Humphry Davy.

In conjunction with Gottlieb Gahn, with W. Hisinger, of Elfstorps Bruk, and with the Swedish physician, Magnus Martin de Pontin, Berzelius made many very extensive observations and published numerous treatises, the most important of which are embraced in the papers named at foot (Sir Humphry Davy, “Bakerian Lectures,” London, 1840, more particularly at pp. 13, 20, 109, 111, 122–123).

As has been before observed, the brilliant investigations of Berzelius and Hisinger, together with those of Nicholson and Carlisle, of Dr. William Henry and of Sir Humphry Davy, actually created a new epoch in the history of chemistry. Prof. Wm. B. Rogers better expressed the fact in his address of Jan. 16, 1879, when saying that “through the labours mainly of Berzelius and of Davy, the great generalization of electro-positive and electro-negative substances was established, and with it the fruitful theory of the electro-chemical exposition of compound bodies.” Such of the experiments of Berzelius as were repeated by Sir Humphry Davy before the English Royal Institution, are embodied in Davy’s paper (partly alluded to above in “Bakerian Lectures”) which was read before the Royal Society, June 30, 1808. According to J. F. W. Herschel, Berzelius and Hisinger ascertained it as a general law, that in all of the chemical decompositions which they effected, the acids and oxygen become transferred to, and accumulated around, the positive pole, and hydrogen, alkaline earths and metals around the negative pole of a voltaic circuit; being transferred in an invisible, and, as it were, a latent or torpid state, by the action of the electric current, through considerable spaces, and even through large quantities of water or other liquid, again to reappear with all their properties at their appropriate resting-places.

Berzelius discovered selenium while examining certain substances found in the acid manufactured at Gripsholm, Sweden. He includes selenium among the metals; but as it is a nonconductor of electricity, also a most imperfect conductor of heat, and as, in other respects, it bears much analogy to sulphur, it is generally placed among the non-metallic combustibles (Brande, “Manual of Chemistry,” London, 1848, Vol. I. p. 435; Berzelius, “Lehrbuch der Chemie,” “Traité,” etc., Paris, 1846, Vol. II. p. 184; “Annales de Chimie et de Physique,” Vol. IX. p. 160; “Annals of Philosophy,” Vol. XIII. p. 401 and Vol. VIII, N.S. p. 104). The important rôle which the high electrical resistance of selenium has in its early days been made to play by Mr. Willoughby Smith, Dr. Werner Siemens and others, is alluded to at pp. 791–794 of Vol. IV supplement to “Ure’s Dict. of Arts,” etc., London, 1878.

For full accounts of Berzelius’ numerous contributions to science, attention is called to the following:

REFERENCES.--“Royal Society Catal. of Sc. Papers,” Vol. I. pp.
330–341; “Gedächtnissrede auf Berzelius ...” Berlin, 1851;
G. Forchammer, “J. J. Berzelius,” 1849; Poggendorff, Vol. I.
pp. 172–175; “Afhandl. i Fisik. ...”; Jos. Thomas, “Dict. of
Biography,” 1870, Vol. I. p. 341; “Report Smiths. Inst.” for
1862, p. 380; “Vetensk. Acad. Handl.”; “La Grande Encyclopédie,”
Vol. VI. p. 478. See likewise, “Journal Frankl. Inst.,” 3rd
Ser., Vol. XVI. pp. 343–348; Faraday’s “Experim. Researches,”
Arts., 746, 870, 960, and Vol. II. pp. 226–228; Gahn at p. 226
of Becquerel’s “Eléments d’El. Ch.,” Paris, 1843; “Annalen der
Physik,” Vol. XXVII. pp. 270, 311, 316, and Vol. XXXVI. p. 260;
Gehlen’s “Journal für die Chem. und Phys.,” Vol. I. p. 115 and
Vol. III. p. 177; John Black, “An Attempt ... Electro-Chem.
Theory,” London, 1814; Gmelin’s “Chemistry,” Vol. I. pp. 400,
457–458, 461–462; “Encycl. Metrop.” (Galvanism), Vol. IV. pp.
221–222; “Sc. Am. Suppl.,” No. 284, p. 4523, for report of
Helmholtz’s Faraday Lecture of April 5, 1881, taken from the
“Chemical News”; Sturgeon’s “Annals,” Vol. VII. pp. 300–303;
Vol. VIII. p. 80; Whewell, “History of the Inductive Sciences,”
1859, Vol. II. pp. 304, 347–348; Thos. Thomson, “An Outline of
the Sciences ...” London, 1830, Chap. XIV. p. 532; Berzelius
and Wöhler on Volcanoes, in Poggendorff’s “Annalen,” Bd. I. s.
221, and Bd. XI. s. 146; “Journal des Savants” for June 1892,
pp. 375–385; J. Berzelius and F. Wöhler, Leipzig, 1901; “Svenskt
Biografiskt Handlexikon,” Herm. Hofberg, Stockholm, pp. 88–89;
“Bibl. Britan.,” Vol. LI, 1812, pp. 174–183 (“Nicholson’s
Journal,” July 1812) for John Gough’s remarks on the hygrometer
of Berzelius (Phil. Mag., Vol. XXXIII. p. 177); “Annales de
Chimie,” Vol. LI. pp. 167, 171; Vol. LXXXVI for 1813, p. 146;
Vol. LXXXVII. pp. 286, etc.; also Vol. LXXIII. pp. 198, 200–201,
the last named giving an account of the ammoniacal amalgam which
Berzelius and Pontin were the first to explain.

=A.D. 1802.=--Thompson (Sir Benjamin), Count Rumford, an eminent scientist, native of Woburn in Massachusetts, Knt., F.R.S., one of the founders of the English Royal Institution, publishes his “Philosophical Memoirs ... being a collection of ... Experimental Investigations ... of Natural Philosophy.”

Though more properly identified with important observations and researches on heat, the question of the nature of which, Dr. Edward L. Youmans says, he was the first to take out of the domain of metaphysics, where it had stood since the days of Aristotle, he has given accounts of some highly important experiments regarding the relative intensities and the chemical properties of light, heat and electricity, which can be seen at pp. 273, etc., Vol. LXXVI. part ii. of the _Phil. Trans._ for 1786. Heat spreads in every direction, whilst the electrical fluid may be arrested in its progress by certain bodies, which have on that account been called non-conductors, but he shows that the Torricellian vacuum affords, on the contrary, a ready passage to the electrical fluid while being a bad conductor of heat.

At p. 30 of George E. Ellis’ “Memoir of Sir Benjamin Thompson,” published in Boston (no date), is reproduced Rumford’s “Account of what expense I have been at toward getting an electrical machine” during 1771, and at pp. 481–488, Vol. I, also pp. 350, 351, Vol. III of the “Complete Works of Count Rumford,” published by the American Academy of Sciences, allusion is made to the galvanic influence in the construction of utensils.

REFERENCES.--Sir W. Thomson, “Mathematical and Physical Papers,”
London, 1890, Vol. III. pp. 123, 124; _Phil. Mag._, Vol. IX for
1801, p. 315; Silliman’s _American Journal of Science_, Vol.
XXXIII. p. 21; “Biog. Universelle,” Tome XXXVII. p. 81; “Journal
des Savants,” for Dec. 1881 and Jan. 1882; “Bibl. Britan.,” Vol.
LVI., 1814, pp. 398–401 (necrology).

=A.D. 1802.=--Pepys (William Haseldine, Sr.), son of an English manufacturer of surgical instruments, who became F.R.S. and was one of the founders of the Askesian Society, as well as of both the London Institution and of the London Geological Society, constructs, during the month of February 1802, the strongest pile hitherto known. It consists of sixty pairs of zinc and copper plates, each six feet square, held in two large troughs filled with thirty-two pounds of water containing two pounds of azotic, or nitric, acid.

It is said that with this battery he succeeded in melting iron wires ranging in diameter from one two-hundredth to one-tenth of an inch, the combustion developing an extremely bright light, while platinum wires, one thirty-second of an inch in diameter, turned to white heat and melted in globules at the point of contact. Charcoal was permanently ignited a length of nearly two inches and the galvanic action was strong enough to light it after passing through a circuit of sixteen persons holding one another by the hand. Gold leaf displayed a bright white light, accompanied with smoke; silver leaf gave an intense green light without sparks, but with still more smoke; while sheets of lead burned actively, with accompaniment of very red sparks mixed with the flame (Figuier, “Exposition,” etc., Paris, 1857, Vol. IV. p. 347).

Later on, another battery was constructed by him for the London Institution. This consisted of 400 pairs of plates five inches square, and of 40 pairs one foot square. With it, Davy ignited cotton, sulphur, resin, oil and ether, melted a platinum wire, burned several inches of an iron wire one three-hundredth of an inch in diameter, and boiled easily such liquids as oil and water, even decomposing and transforming them into gases. It was during the year 1808 that Pepys finished the enormous battery of 2000 double plates already alluded to under the Cruikshanks (A.D. 1800) and the Davy (A.D. 1801) articles, and which is to be found described at p. 110 of the “Elements of Chemical Philosophy.”

One year before that (1807) Pepys constructed a new form of eudiometer, of which a description was given before the Royal Society on the 4th of June, as shown at p. 270 Vol. I of the “Abstracts of Papers,” etc., of that Institution, as well as in the 1807 volume of the _Philosophical Transactions_.

Of the many ingenious experiments by which Pepys distinguished himself, scarcely none attracted more attention than those which are referred to in the last-named _Transactions_ for 1866, pp. 339–439. It is only since 1815, when he employed the electric current to heat iron wire and diamond dust together, whereby he obtained steel, that the direct carburization of iron by the diamond has been clearly established. Prior to this date, during 1798, Clouet had melted a little crucible of iron weighing 57·8 grammes containing a diamond weighing 0·907 gramme, and produced a fused mass of steel. Guyton de Morveau reported upon Clouet’s experiment in the _Annales de Chimie_ for 1799 (Vol. XXXI. p. 328) and his investigations were repeated by many scientists, notably by Margueritte, as recently as 1865. The latter’s observations, which were communicated to the _Annales de Chimie et de Physique_ (Tome VI), showed that, although carburization can be effected by simple contact of carbon and iron in a gaseous atmosphere, it is nevertheless true that in the ordinary process of cementation the carbonic oxide gas plays an important part, which had until then been overlooked (Translation of Prof. W. C. Roberts-Austen, F.R.S. For Mr. Children’s investigations in the same line, see the _Phil. Trans._ for 1815, p. 370, also A.D. 1809).

Sir Humphry Davy employed in his experiments on the decomposition and composition of the fixed alkalies two mercurial gasometers of Pepys’ design, described in No. 14 of the _Phil. Trans._ for 1807, in conjunction with the same apparatus used by Messrs. Allen and Pepys for the combustion of the diamond (“Bakerian Lectures,” London, 1840, pp. 84 and 93).

During the year 1822 Pepys constructed for electro-magnetic experiments a very large spiral galvanic battery, which was put together for the London Institution on the plan of the one first built by Dr. Robert Hare, Professor of Chemistry in the University of Pennsylvania. Pepys called it a _calorimotor_, by reason of its remarkable power of producing heat, and it is well illustrated in the 8th Edit. “Encyclopædia Britannica” article on “Voltaic Electricity.” It consisted only of two metallic sheets, copper and zinc, fifty to sixty feet long by two feet wide, coiled around a cylinder of wood and prevented from coming together by three ropes of horse-hair, the whole being suspended over a tub of acid so that, by a pulley or otherwise, it could be immersed or taken up. As stated in Vol. V of the _Trans. of the Amer. Phil. Soc._, this battery required nearly fifty-five gallons of fluid, and the solution used contained about one-fortieth of strong nitrous acid.

When, as Noad observes, it is stated that a piece of platinum wire may be heated to redness by a pair of plates only four inches long and two broad, the calorific power of such an arrangement as the above may be imagined to have been immense. The energy of the simple circle depends on the size of the plates, the intensity of the chemical action on the oxidizable metal, the rapidity of its oxidation, and the speedy removal of the oxide. Pouillet is said to have constructed one of these batteries with twelve couples for the Paris Faculté des Sciences, and found it very powerful in producing large quantities of electricity with low tension. The best liquid for this battery was water with one-fortieth in volume of sulphuric acid and one-sixtieth of nitric acid. With the above-described battery of Mr. Pepys, Sir Humphry Davy performed a remarkable experiment which is to be found described in the _Phil. Trans._ for 1823. A similar apparatus was produced independently, at about the same time, by Dr. Seebeck, of Berlin.

Another of Pepys’ inventions is the substitution, for the tinfoil coatings within the glass of Bennet’s electroscope, of two plates, forming an acute angle, which, by means of a regulating screw, can be adjusted to any required distance from the gold leaves. The angular part is secured to the bottom; the open part perpendicularly upward. By this mode of approximating the coatings to the gold leaves, the resistance being diminished, a weaker intensity of electricity suffices for their disturbance.

REFERENCES.--_Quarterly Journal of Science_, Vol. I for 1816;
_Phil. Mag._, Vol. XXI. p. 241; XLI. p. 15; Becquerel, Vol. I.
p. 34. Mr. William H. Pepys, Jr., published descriptions of the
newly invented galvanometer and of the large galvanic apparatus
in the _Phil. Mag._, Vol. X., June 1801, p. 38, and Vol. XV
for 1803, p. 94; “Cat. Sc. Papers Roy. Soc.,” Vol. II. p. 192;
“Bibl. Britan.,” Vol. XVIII, 1801, p. 343, and Vol. XXII, 1803,
p. 297.

=A.D. 1803.=--Geoffroy Saint-Hilaire (Etienne), a very eminent French naturalist, once the pupil of Haüy, whose life he was the means of saving during the massacre of September 1792, is the first to give a thoroughly complete description of the electrical organs and functions of the _raia torpedo_, of the _gymnotus electricus_, of the _silurus electricus_, and of other similar species of fishes. His work on the subject, entitled “Sur l’anatomie comparée,” etc., is alluded to in Vol. I. An. xi. No. 5 of the “Annales du Museum,” whence it is translated for the fifteenth volume of the _Phil. Mag._

His analyzation of the fluid in the cells of the _torpedo_ showed it to consist of albumen and gelatine; and he discovered some organs analogous to those of the _torpedo_ in different species of the same genus _raia_, which, strange to say, do not appear possessed of any electrical power.

The electrical organs of the _silurus electricus_ he found to be much less complicated than those of other electrical fishes. They lie immediately below the skin and stretch all around the body of the animal. Their substance, he says, is a reticulated mass, the meshes of which are plainly visible, and these cells are filled, like those of other electrical fishes, with an albuminous gelatinous matter. The nerves distributed over the electrical organs proceed from the brain, and the two nerves of the eighth pair have a direction and nature peculiar to this species. (Consult C. Matteucci, “Traité des Phénomènes ...” Paris, 1844, Chaps. VI and VII. pp. 301–327.)

In his great work on Egypt (Pl. XII, 2) Geoffroy gives the figure of a _malapterus electricus_ (see Adanson, A.D. 1751) which is opened to show the viscera, but, by a singular inaccuracy, says Mr. James Wilson, the fish is represented as scaly, whereas there are no scales whatever upon this fish, and no fish known to possess electric powers has either scales or spines. The _torpedo_, the _gymnotus_ and the _malapterus_ have all naked skins. The _tetraodon electricus_ (see Shaw at A.D. 1791) is also destitute of spines on the skin, although all its congeners have skins as bristly as those of a hedgehog.

Geoffroy Saint-Hilaire (Isidore), son of Etienne, was also a distinguished naturalist. He became Assistant Professor of Zoölogy to his father in 1829, likewise his assistant at the Faculté des Sciences in 1837, and, when Etienne became blind, during the year 1841, he succeeded to the Professorship of Zoölogy at the Museum of Natural History. He is the author of “The Life, Works and Theories (_Vie, Travaux et Doctrine_) of Etienne Geoffroy Saint-Hilaire,” Paris, 1847.

REFERENCES.--Gilbert’s _Annalen_, XIV. p. 397; _Bulletin Soc.
Phil._, No. 70; Geo. Wilson’s “Life of Cavendish,” London, 1851,
p. 469, alluding to the later experiments on electrical fishes
made by Faraday (1838), Dr. James Stark, of Edinburgh (1844),
Prof. Goodsir (1845), and Dr. C. Robin (1846). Consult also,
_Journal de Physique_, Vol. LVI. p. 242, and the complete list
of Geoffroy’s works in Callisen’s “Medicinisches-Schriftsteller
Lexicon”; “Memoir of M. Isidore G. Saint Hilaire,” by M. De
Quatrefages, in “Report of Smithsonian Institution” for 1872,
pp. 384–394; “Journal des Savants” for May-Aug., 1864; “Roy.
Soc. Cat. of Sc. Papers,” Vol. II. pp. 824–832; Vol. VI. p. 669;
Vol. VII. p. 757.

=A.D. 1803.=--Carpue (J. C. S.), English scientist, relates, in his “Introduction to Electricity and Galvanism,” published in London, some noteworthy experiments on the curative action of common electricity.

He repeated many of the investigations of Giovanni Aldini, and, in the presence of Dr. Pearson and other medical gentlemen, experimented upon the body of Michael Carney, immediately after his execution for murder. Carpue’s main object was to ascertain whether galvanism, applied at once to the nerves, could excite action in the internal parts, and especially in the respiratory organs. He first made an opening into the windpipe and, after introducing about three pints of oxygen into the lungs, he applied conductors to the phrenic nerve as well as to other parts of the body, the lungs being at the same time occasionally inflated, but no action could be excited in the diaphragm. The application of conductors to the inside of the nostrils and elsewhere, however, excited very considerable contractions in the right auricle more than three hours after death, the ventricles being, as in Aldini’s experiments, perfectly motionless.

REFERENCES.--“Galvanic Experiments Made by Carpue on the Body of
Michael Carney,” etc., London, 1804 (_Phil. Mag._, Vol. XVIII.
p. 90); the “Encyclopedia Metropolitana,” article “Galvanism,”
Vol. IV. pp. 105, 106, also the “Introduction,” etc., above
named for descriptions of Mr. Cuthbertson’s plate electrical
machine and of Mr. Read’s condenser.

=A.D. 1803.=--Hachette (Jean Nicholas Pierre), a protégé of Monge, who became professor at the Paris Ecole Polytechnique, where he had among his pupils Poisson, Arago and Fresnel, presents to the Institut National the dry pile which was the result of the many experiments he had carried on in conjunction with Charles Bernard Desormes, who was then known as a prominent French scientist and manufacturer of chemical products.

Their idea was to establish the development of electricity by simple contact, and they sought to obtain a substance which would satisfactorily replace the wet discs, and not be affected by the metals, as had been all the liquids hitherto employed (H. Boissier, “Mémoire,” etc., Paris, 1801). After numerous investigations they adopted a compound consisting of common starch and either salts, varnishes or gums, with which they made the necessary discs. These discs were dried and placed alternately between the copper and zinc couples, but were afterward found to be too easily affected by moisture to prove very effective (D. Tommasi, “Traité des Piles Electriques,” Paris, 1889, p. 529).

In the columns of the _Annales de Chimie_, named below, will be found detailed the numerous experiments with the galvanic pile carried on individually and collectively by Hachette, Desormes and other scientists; those of Hachette and Thénard upon the ignition of metallic wires claiming especial notice. Prof. John Farrar (“Elem. of Elec. Magn.,” etc., Cambridge, 1826, p. 167) calls attention to the latter and in the _Phil. Mag._ for 1821 will be found an account of the researches of the above-named scientists made during the year 1805, to establish more properly the analogy between galvanism and magnetism. Hachette and Desormes endeavoured to ascertain the direction which would be taken by a voltaic pile, whose poles were not joined, when freely suspended horizontally. Their pile, as Fahie gives it, was composed of 1480 thin plates of copper tinned with zinc, of the diameter of a five-franc piece, and was placed upon a boat floating on the water of a large vat; but it assumed no determinate direction, although a magnetized steel bar, of a weight nearly equal to that of the pile, and likewise placed upon the boat, would turn, after some oscillations, into the magnetic meridian.

REFERENCES.--_Annales de Chimie_, Vol. XXXVII. pp. 284–321;
XLIV. pp. 267–284; XLVII (Biot’s Observations), p. 13; XLIX.
pp. 45–54, and XLV for 1808. See also, the _Annales_ for 1834,
as well as Vol. XLII. p. 125, for experiments of MM. Desormes
and Clement on the fixed alkalies; _Journal de Physique_
of Sept. 1820, for the paper of Hachette and Ampère on the
electro-magnetic experiments of Oersted and Ampère; _Annales de
Chimie et de Physique_, Vol. II for May 1816, pp. 76–79, and V.
p. 191; _Phil Mag._, Vol. LVII. p. 43; L. W. Gilbert, _Annalen
der Physik_, Vols. IX. pp. 18–39; XVII. pp. 414–427; _Journal de
l’Ecole Polytechnique_, Vol. IV for 1802; XI. p. 284; Leithead,
“Electricity,” p. 252; _Bull. de la Soc. Philomathique_, No. 83;
P. Sue, aîné, “Hist. du Galv.,” Paris, An. X, 1802, Vol. II. pp.
160, 167, 188, 345 (Hachette et Thénard), and p. 371; Joseph
Izarn, “Manuel du Galvanisme,” An. XII, 1804, s. 4. p. 179;
Poggendorff, Vol. I. pp. 562, 985; Larousse, “Dict. Universel,”
Vol. VI. p. 576; “Royal Society Catalogue of Scientific Papers,”
Vol. III. pp. 106–109.

=A.D. 1803.=--Biot (Jean Baptiste), who, in 1800, at the age of twenty-six, was made Professor of Natural Philosophy at the “Collège de France,” and afterward ranked among the first astronomers and mathematicians, gives an account of his journey to Aigle, in the Department of l’Orne, whither he was sent by the Government to examine and report upon a very extraordinary shower of meteorites. The facts obtained by him were communicated to the Institute on the 29th Messidor, An. XI, and also appeared at the time in the Paris _Journal des Débats_ (_Phil. Mag._, Vol. XVI. p. 299).

On the 23rd of August of the year following (1804) Biot accompanied Gay-Lussac in the latter’s first memorable balloon ascent. This aeronautic voyage, sanctioned by the French Government mainly through the efforts of Berthollet and Laplace, was the first of the kind undertaken solely for a scientific object.

Besides numerous barometers and electrometers, Biot and Gay-Lussac carried with them two compasses, a dipping needle and other instruments. For the examination of the electricity of different strata of the atmosphere, they had several metallic wires from 60 to 300 feet in length, also a small electrophorus feebly charged, while for galvanic experiments they added some discs of copper and zinc, together with a supply of frogs, insects and birds. An account of the exceedingly important results obtained by those scientists at different elevations, of which the highest reached exceeded four miles, was read before the National Institute, Aug. 27, 1804. It was also published in London during the latter year, and alluded to at p. 371, Vol. XIX of the _Philosophical Magazine_. Mary Somerville remarks (“Connection of the Physical Sciences,” 1846, p. 334) that according to the observations of Biot and Gay-Lussac, the magnetic action is not confined to the surface of the earth, but extends into space. The moon has become highly magnetic by induction, in consequence of her proximity to the earth, and because her greatest diameter always points toward it. Her influence on terrestrial magnetism is now ascertained; the magnetism of the hemisphere that is turned toward the earth attracts the pole of our needles that is turned toward the south and increases the magnetism of our hemisphere; and as the magnetic, like the gravitating force, extends through space, the induction of the sun, moon and planets must occasion perpetual variations in the intensity of terrestrial magnetism, by the continual changes in their relative positions.

In 1805 Biot published an investigation of the laws which should govern the dip and intensity, in the hypothesis of a magnet situated at the centre of the earth, having its poles infinitely close to each other and directed to opposite points on the surface of the globe and, as justly adds Major Edward Sabine (Report Seventh Meeting Brit. Asso.), it is a well-known consequence of this hypothesis that the lines of equal dip and equal intensity on the earth’s surface should everywhere be parallel to each other. The phenomena of electricity had been brought within the pale of mixed mathematics by C. A. Coulomb (A.D. 1785), whose considerations mainly attached to the distribution of electricity upon the surface of spheres, and his investigations were at once diligently pursued by the French scientists, Biot, Laplace and Poisson. Laplace, who undertook to investigate the distribution of electricity upon the surface of ellipsoids of revolution, showed that the thickness of the coating of the fluid at the pole was to its thickness at the equator as the equatorial is to the polar diameter, or, what is the same thing, that the repulsive force of the fluid, or its tension at the pole, is to that at the equator as the polar is to the equatorial axis. Biot extended this investigation to all spheroids differing little from a sphere, whatever may be the irregularity of their figure, and his solution of the problem will be found in No. 51 of the _Bulletin des Sciences_. He also determined, analytically, that the losses of electricity form a geometrical progression when the two surfaces of a jar or plate of coated glass are discharged by successive contacts, and he found that the same law regulated the discharge when a series of jars or plates are placed in communication with each other (Whewell, “History of the Inductive Sciences,” Vol. II. pp. 208, 223; Noad’s “Manual,” p. 15; Eighth “Britannica,” Vol. VIII. p. 531. For Biot’s experiments, touching upon electrical attraction and demonstrating practically the distribution of electricity upon the surface of a conductor, see the last-named volume of the “Britannica,” pp. 552, 556, and Noad, p. 56).

In conjunction with Frederick Cuvier, Mr. Biot investigated the connection of chemical charge with the production of electricity. Like Mr. W. H. Pepys, they examined the effect produced by the pile on the atmosphere in which it is located. Mr. Pepys placed the pile in an atmosphere of oxygen, and found that in the course of a night 200 cubic inches of the gas had been absorbed, but that in an atmosphere of azote the pile ceased to act. Biot and Cuvier likewise observed the quantity of oxygen absorbed, and inferred from their experiments that “although, strictly speaking, the evolution of electricity in the pile was produced by oxidation, the share which this had in producing the effects of the instrument bore no comparison with that which was due to the contact of the metals, the extremity of the series being in communication with the ground.” Their investigation was attended by the discovery that as long as any oxygen remained to be absorbed, the chemical and physiological effects of the apparatus still continued, but with decreasing intensity; so that if the conducting wires attached to the two poles are made to return from under the receiver in tubes of glass they may be used to decompose water and communicate shocks to the organs. All these effects, however, cease when the surrounding oxygen is exhausted (_Annales de Chimie_, Vol. XXXIX. p. 242; _Soc. Philomathique_, An. IX. p. 40; Sue, “Histoire du Galv.,” Vol. II. p. 161).

In the second volume of Biot’s “Traité de Physique” will be found recorded his many observations on the nature and origin of the electric light, extracts from which are given by Sir David Brewster in the electricity article of the “Britannica.” Biot remarks that the light which is observed during an electric explosion was for a long time considered by philosophers as a modification of the electric principle itself, which they supposed to be the quality of becoming luminous at a certain degree of accumulation (John Farrar, “Elem. of Elec., Mag. and El. Mag.,” 1826, p. 118). Brewster adds that this eminent French writer, however, considered the opinion as erroneous, and he has devoted a whole chapter to prove that electricity has the same origin as the light disengaged from air by mechanical pressure, “and that it is purely the effect of the compression produced on the air by the explosion of electricity.” In order to establish this theory, Mr. Biot has stated, on the authority of several experiments, “that the intensity of electric light depends always on the ratio which exists between the quantity of electricity transmitted and the resistance of the medium”; and he has shown, by an experiment with Kinnersley’s thermometer, “that at each spark the air of the cylinder, driven by the repulsive force, presses on the surface of mercury, which rises suddenly in the small tube, and falls back again immediately after the explosion.” He adds:

“This indication proves the separation produced between the particles of the mass of air where the electricity passes; and from what we know of its extreme velocity it is certain that the particles exposed immediately to its shock ought in the first moment to sustain individually all the effect of the compression. They ought, then, from this cause alone to disengage light, as when they are subjected to any other mechanical pressure. Thus one part at least of the electric light is necessarily due to this cause; and this being the case, there is no experiment which can lead us to conjecture that it is not all due to this cause.”