1lISrORY. The earliest electro-chemical ob servation on record %vas made by Heimann and Pacts van Truostwvk, of Ilaarlem, in 1789. The experiment was carried out as follows: a glass tube with one end closed and the other open, and with a metal wire sealed into the closed end, was filled with water and inverted over a dish of water; a second metal wire was passed through the open end of the tube, up to within some distance of the end of the upper wire; and electric sparks were caused to pass between the ends of the two wires. The result was that water was decomposed into its constituents, oxygen and hydrogen, a mixture of which collected in the upper part of the tube. _\s long as the end of the upper electrode remained immersed in water, nothing further happened; but the instant the end of the electrode became exposed to the mix ture, a \ iolent explosion took place, owing to the re•conibination of the two elements. hi a similar manner, Hitter afterwards carried out the first true electrolysis., using silver wires as electrodes and a solution of a silver salt as the electrolyte. Then came Volta's eelebrated experiments, which resulted in his invention of voltaic batteries (see Vut.TAIC BATTERY) : and in 1793 Volta was able to prepare the first electro-chemical series. An appreciation of the work of Davy and Berzelius, and of the sway of Berzelius's ideas exercised for niany years in the science of chemistry, may be found in the article ('u•misTny (historical sec tion). Faraday's discovery. in 1834. of the true laws of electrolysis marked a great step forward both in chemistry and in the science of electricity. The vonception of energy, of its several forms, and of their mutual transformations. was devel oped in course of the fifth and sixth decades of the nineteenth ventu•y. and in 1817 Helmholtz tirst advanced the belief that the heat of the chemical reactions of a cell may be entirely transformed into electrical energy. Haying been again brought forward by Thomson in 1831. the belief became known in science as `Thomson's law."L'he researches establishing the true relation were carried out by Gibbs in 1878 and by Helmholtz in 188•. and Were completed by
the experimental investigations of Czapski and Jahn. In 1886 Van't llolf introduced the modern theory of osmotic pressure (see 8Qi.•TIox and in 1887 Arrhenius advanced the theory of elec trolytic dissociation (see Dissociarms), which is at the basis of the most important chapters of modern electric-cheinistry. The idea that electrolytes must be more or less broken up in their solutions originated with Clausius: but Arrhenius was the first to give to it its present quantitative form, to connect it with the theory of solutions, and to demonstrate its great im portance for theoretical chemistry. The re search•s of Ilittorl on the relative rates of trans portation of the ions during electrolysis were carried out as early as 1833 to 1839. but gained great scientific importance only after Arrhenius established his theory of dissociation. Other important names •onnect(ml with the progress of general electro-chemistry are those of Ostwald. :Nernst. Planck, 1.e Mane. and lioldrausch. The concept of electrons originated in Helmmholtz's lectUres ()II Faraday's ideas of electricity, deliv ered in London in 1881. .1niong those who have contributed to the recent development of this promising idea are Nernst. Abegg. and Bodliinder Biumom(ArnY. Jahn, (;rundriss der Elektio •hcntic (Vienna, 1893) ; Ise Blanc, The Elements of Electro-('hemisfry, translated by Whit ney New York. 1896) Ost•ald. Elehlrocheniie, ihic GcSchichlc !Ind Lehre ( Lei pzig, 1896 ) ; Loeb, (;ruurf;iiyc de?. Eh-L./roe/H•10c (Leipzig. 1897) ; 11 aber. Grumlzii ye der lechnisehen Elektrochemie oaf thcoretischer Grum/If:ye (Leipzig, 1898): Liipke, Grucidzuqc der !'.lektrochcntir ( 1899) Jones, The Theory of Elf etrolyti• Disso ciation and Some of Its Jpplicetions New York, 19(10): .looes, outlines of Ele•tro-Chemistry (New York, 1901) ; Arrhenius, Lehrbuch der Eleko-ochentie (Leipzig, 19(11) ; Nernst and 13,,r (editors), Jahr/Judi der L'lcktrnchcmic (Halle). See CHEMISTRY; ELECTRICITY; VOLTAIC' CELLS; DISSOCIATION; SOLUTION; ANALYsIS. CHEMICAL.