talk of the town, and the highest ranks of society began to throng the theatre of the Royal Institution whenever Davy was announced to give a lecture. He was, as the saying goes, the lion of the metropolis, and was carried away by the tide of fashionable life. During the hours of the day he attended to his duties at the Royal Institution, and pursued his scientific researches with the same ardor as ever, but he "devoted the evening to social intercourse with the aristocracy of birth and brain, with all the thoroughness of his nature."
In 1802-'3 he delivered a course of lectures on agricultural chemistry. These lectures were afterward published under the title of "Elements of Agricultural Chemistry," and the work passed through many editions at home, besides being translated into almost every language of Europe. His observations on the chemistry of tanning were published in 1803 in the "Philosophical Transactions." His researches on electro-chemistry, begun at Clifton, were continued at the Royal Institution. His two famous "Bakerian Lectures," the first on the laws of electricity in relation to chemical combination, and the second on the results of the application of these laws, were delivered in 1806 and 1807 respectively. He discovered the base potassium October 6, 1807; sodium and other bases soon afterward. We are told that "when he saw the globules of potassium appear and take fire as they entered the air, his delight was so great that for some time he could not compose himself sufficiently to continue the experiment." Indeed, his mental labor and the excitement over his discoveries had such an effect on his general constitution, that for several weeks he lay seriously ill. On his recovery he presented to the Royal Institution the battery of two thousand cells with which he had made these great discoveries. It was with this battery that, in 1813, he produced for the first time the electric light. When the current from this pile was passed between two pointed pieces of wood charcoal, attached to conducting wires, a light was produced of such dazzling brilliancy as to be comparable only with sunlight. The length of this electric arc was four inches.
In 1803 he was elected a Fellow of the London Royal Society. He was knighted in 1813, and the same year married a wealthy widow, Mrs. Apreece. His "Elements of Chemical Philosophy" were published this year. He now resigned his professorship at the Royal Institution, and in the following year visited the Continent of Europe. At Paris he was received with distinguished honor by the Academy of Sciences, and demonstrated to that august body that iodine is an element. He remained abroad some two years, in the mean time diligently pursuing his chemical researches. At Florence he investigated the nature of the diamond, which he proved to be an allotropic form of carbon. His researches on colors and on the iodine compounds were also carried on during this period.
In 1815 he made the tour of Scotland, and on his homeward journey visited the coal districts of England. A committee of colliery proprie-
