846 DAVY year lie published a volume entitled Researches, Chemical and Philosophical, chiefly concerning Nitrous Oxide and its Respiration. Whilst the impression created by this publication was still fresh on the public mind, Davy was recommended to Count Rumford by Mr Underwood and Dr Hope as a suitable person to succeed Dr Garnet as lecturer on chemistry at the Royal Institution recently established in London ; and accordingly, on February 16, 1801, he was chosen assistant lecturer to the Institution, and director of the laboratory ; his appointment to the lectureship took place six weeks later. A minute on the records of the Royal Institution shows that he was ap pointed professor of chemistry on the 31st of May 1802. The ungainly exterior and peculiar manner of Davy on his first appearance in London prejudiced Rumford and others against him ; when, however, he began to lecture, he won the approbation of all. His ingenuity and happy facility of illustration gained him a high reputation ; his company was courted by the choicest society of the metropolis ; and soon his presence was regarded as indis pensable in the soirees of the fashionable world. His style of lecturing was well adapted to command attention it was animated, clear, and impressive, notwithstanding the naturally inharmonious tones of his voice ; his experiments, moreover, were both ingeniously conceived and neatly exe cuted. The young chemist was fortunate in the time in which he commenced his metropolitan career. Experimental chemistry was beginning to be the fashion of the day ; and the discovery of the decomposition of chemical substances by voltaic electricity had excited the greatest interest amongst the votaries of science. The liberality of the committee of the Royal Institution supplied to Davy what few private individuals could afford a battery of 400 five- inch plates, and one of 40 plates a foot in diameter. With these were conducted the brilliant investigations which resulted in his discovery of potassium and sodium. The earliest of Davy s communications to the Royal Society, and the first of his contributions to electro-chemis try, was " An Account of some Galvanic Combinations formed by an arrangement of single Metallic Plates and Fluids," read in June 1801. In all hitherto constructed piles, plates of two metals, or one plate of metal and another of charcoal, and some interposed fluid had been employed. Davy showed in this paper that a battery might be constructed of a single metal and two fluids, provided one of the fluids was capable of causing oxidation on one of the surfaces of the metal. In addition to the duties of his situation in the Royal Institution, to which those of joint editor of the Journal had been added, Davy for ten succes sive years gave courses of lectures for the Board of Agri culture on the connection between agriculture and chemistry. In 1803 he was admitted a member of the Royal Society, of which he, in January 1807, became the secretary. The most valuable of all his scientific writings are his communi cations to the Royal Society, scarcely one of which does not announce some new and important fact, or elucidate some principle of experimental philosophy. In February 1803 he read to the society an essay " On Astringent Vege tables, and their Operation in Tanning " and in 1805 An Account of some Analytic Experiments on Wavellite," and a paper " On the Method of Analyzing Stones contain ing a Fixed Alkali, by Boracic Acid." This method is founded on the strong affinity of that acid for different substances at a high temperature, and on the ease with which borates are decomposed by mineral acids. In his first Bakerian lecture, delivered to the Royal Society in November 1806, Davy showed that electro-chemical phenomena were explicable by one general law, and illus trated his theory of voltaic action by numerous happily- devised experiments. After pointing out that in all voltaic decompositions acids appeared at the positive and bases at the negative pole, he generalized his results by stating that hydrogen, the alkalies, earths, metals, and certain oxides are attracted by negatively electrified and repelled by positively electrified metallic surfaces, and that oxygen and acids are attracted by positively and repelled by negatively electrified metallic surfaces. He then pro ceeded to investigate the law of electro-chemical action, and concluded that electro-chemical combinations and decompositions are referable to the law of electric attractions and repulsions, and that both " chemical and electrical attractions are produced by the same cause, acting in the one case on the particles, in the other on the masses." For these researches the French Institute awarded him the prize of 3000 francs offered by the first consul for the experiment most conducive to the progress of science. Davy s discovery of the production of potassium and sodium by the electrical decomposition of their alkalies was made in October 1807, and an account of the new metals was given to the Royal Society on the 19th of November in the second Bakerian lecture. On the 23d of that month a severe fever attacked him, and he was unable to resume his professorial duties at the Royal Institution till March 12, 1808. In the meanwhile barium and calcium, the existence of which had been predicted by Davy, were dis covered by Berzelius and Pontin. In 1 808 Davy announced to the Royal Society his discovery of magnesium and strontium. Alumina, silica, and zirconia he was unable to decompose, but he showed it to be highly probable that they contained metallic bases. Various opinions as to the nature of the new metals of the alkalies and alkaline earths were at first entertained, some chemists considering them to be compounds of hydrogen with unknown bases. In the third Bakerian lecture, read in December 1808, and its appendix of next spring, Davy adduced conclusive evidence of the elementary nature of potassium ; he discussed also the nature of sulphur, phosphorus, and carbon, and described the preparation of boron, which he then regarded as a metal. The original galvanic batteries used by Davy having become unserviceable through wear, a liberal voluntary subscription among the members of the Royal Institution, in July 1808, put him in possession of a battery of 2000 double plates, with a surface equal to 128,000 square inches. His electro-chemical discoveries had, however, all been made before this new power was provided. The fourth Bakerian lecture, read in November 1809, brings forward proofs that oxymuriatic acid, contrary to Davy s previous supposition, is a simple body, termed by him chlorine (see vol. v. p. 678), and that muriatic acid is a compound of that element and hydrogen. Davy s reputation had now reached its zenith ; and his audience in the theatre of the Royal Institution numbered little less than 1000. At the invitation of the Dublin Society he gave, in November 1810, a* course of lectures on electro-chemical science, and in the following year other courses on the elements of chemical philosophy and on geology. For the first of these he received 525, and for the two latter 750; and before he left Dublin, Trinity College conferred upon him the degree of LL.D. On the 8th April 1812 Davy was knighted by the Prince Regent ; on the next day he gave his farewell lecture at the Royal Institution ; and on the llth he married Mrs Appreece, daughter and heiress of Charles Kerr of Kelso, with whom he had a considerable fortune. His usual employments were in great measure suspended during the winter of 1812 in consequence of an injury to an eye, resulting from an explosion of chloride of nitrogen, which he had begun to experiment upon after receiving intelligence of its discovery by Dulong. The first and, as it proved,
the only volume of Davy s Elements of Chemical Philosophy