In Vols. II, IV and V he discourses about the extent of the magnetic fluid and explains the phenomena of meteors, St. Elmo’s fire, thunder, etc., besides recording the experiments of Grey, Dufay and others.
A.D. 1733.—Dufay (Charles François de Cisternay), French scientist and superintendent of the Jardin du Roi, now the Jardin des Plantes, of Paris (in which latter position he was succeeded by Buffon), communicates to the French Academy of Sciences the history of electricity brought down to the year 1732 (Dantzig Memoirs, Vol. I. p. 195).
He is said to have originated the theory of two kinds of electricity permeating matter and producing all the known phenomena of attraction, repulsion and induction, though the honour of this important discovery should be shared by M. White, who was associated at one time with Stephen Grey and who, it appears, independently discovered the fact while in England. Dufay thus announces his discovery: “... there are two kinds of electricity, very different from one another, one of which I call vitreous (positive) and the other resinous (negative) electricity. The first is that of glass, rock crystal, precious stones, hairs of animals, wool and many other bodies. The second is that of amber, copal, gum-lac, silk, thread, paper and a vast number of other substances. The characteristics of these two electricities are that they repel themselves and attract each other. Thus a body of the vitreous electricity repels all other bodies possessed of the vitreous, and, on the contrary, attracts all those of the resinous electricity. The resinous also repels the resinous and attracts the vitreous. From this principle one may easily deduce the explanation of a great number of the phenomena; and it is probable that this truth will lead us to the discovery of many other things” (see Franklin, at A.D. 1752, and Symmer, at A.D. 1759).
Upon repeating Grey’s experiments, Dufay observed, amongst other things, that, by wetting pack thread, electricity was more readily transmitted through it, and he was enabled thus easily to convey the fluid a distance of 1256 feet, though the wind was high and although the line made eight returns.
References.—Fontenelle, “Eloge”; Priestley, “History and Present State of Electricity,” 1775, Period IV. pp. 43–54; Sturgeon, Lectures, 1842, p. 23; “An Epitome of El. and Mag.,” Philad., 1809, p. 29; Mém. de l’Acad. Royale des Sciences for 1733, pp. 23, 28, 76, 83, 233–236, 251, 252, 457; also for the years 1734, pp. 303, 341, and 1737, pp. 86, 307; Phil. Trans., Vol. XXXVIII. p. 258; also the following abridgments: Hutton, Vol. VII. p. 638; John Martyn, Vol. VIII. part ii. p. 393; Baddam, Vol. IX. p. 497; Thos. Thomson, “An Outline of the Sciences of Heat and Electricity,” London, 1830, p. 344 and Thos. Thomson, “Hist. of the Roy. Soc.,” London, 1812, p. 432; “Electricity in the Service of Man,” R. Wormell (from the German of Dr. Urbanitzky), London, 1900, p. 14; “Journal des Sçavans,” Vol. XCIII for 1731, pp. 383–388; Vol. C for 1733, p. 244; Vol. CIV for 1734, p. 479; Vol. CXII for 1737, p. 65; Vol. CXV for 1738, p. 173; Vol. CXXIX for 1743, p. 501.
A.D. 1733.—Winckler (Johann Heinrich), a philosopher of Wingendorf, Saxony, and Professor of Languages in the University of Leipzig, first uses a fixed cushion in the electric machine for applying friction instead of by means of the hand, and is, by many, believed to have been the first to suggest the use of conductors as a means of protection against lightning (see B.C. 600).
In March 1745, Winckler read a paper before the Royal Society, in which he describes machines for rubbing tubes and globes, also a contrivance with which he can give his globes as many as 680 turns in a minute. Priestley states that the German electricians generally used several globes at a time and that they could excite such a prodigious power of electricity from “globes, whirled by a large wheel and rubbed with woollen cloth or a dry hand, that, if we may credit their own accounts, the blood could be drawn from the finger by an electric spark; the skin would burst and a wound appear, as if made by a caustic.”
During the year 1746 Winckler made use of common electricity for telegraphic communications by the discharge of Leyden jars through very long circuits, in some of which the River Pleisse formed a part, and it may be added that Joseph Franz had previously discharged the contents of a jar through 1500 feet of iron wire while in the city of Vienna.
References.—Phil. Trans., Vol. XLIII. p. 307; Vol. XLIV. pp. 211, 397; Vol. XLV. p. 262; Vol. XLVII. p. 231; Vol. XLVIII. p. 772; also following abridgments: Hutton, Vol. IX. pp. 74, 109, 251, 345, 494; Vol. X. pp. 197, 529; John Martyn, Vol. X. part ii. pp. 269, 273, 327, 345, 399; Priestley, 1775, on the discoveries of the Germans, pp. 70–77; “Thoughts on the Properties,” etc., Leipzig, 1744, pp. 146, 149.
A.D. 1733.—Brandt (Georg), Swedish chemist, gives in the “Memoirs of the Academy” of Upsal an account of the experiments made by him to show the possibility of imparting magnetism to substances which are not ferruginous. He proved it in the case of the metal cobalt, and during the year 1750 the able discoverer of nickel, Axel. F. de Cronstedt, showed that the latter is likewise susceptible of this property.