SKETCH OF SIR HUMPHRY DAVY. 815 



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 Boyal 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 chemis- 

 try. These lectures were afterward published under the title of " Ele- 

 ments 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 pub- 

 lished in 1803 in the " Philosophical Transactions." His researches on 

 electro-chemistry, begun at Clifton, were continued at the Royal Insti- 

 tution. 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 efi'ect 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 pub- 

 lished this year. He now resigned his professorship at the Royal In- 

 stitution, 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 ele- 

 ment. He remained abroad some two years, in t^he mean time diligently 

 pursuing his chemical researches. At Florence he investigated the na- 

 ture of the diamond, which he proved to be an allotropic form of car- 

 bon. 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- 



