DA'VY, Sir (1778-1829). A cele brated English natural philosopher. He was born December 17, 1778. at Penzance. in Corn wall, where his father was a carver in wood. At the school of Truro, where he was educated until he was fifteen, he showed little relish for classical learning, but was distinguished for a highly retentive memory and an early passion for poetry, which never forsook him. In 1795 be became apprenticed to a surgeon and apothe cary at Penzance. At the same time be entered upon a course of study all but universal: "specu lations on religion and polities, on metaphysics and morals. are placed in his note-books in juxtaposition with stanzas of poetry and frag ments of romance." A system of mathematical study. skeptical philosophy, Scotch metaphysics, and German transcendentalism successively en gaged his attention. The study of natural phi losophy brought him nearer to that department which was to he his own: but it was not till he had reached his nineteenth year that be entered seriously upon the study of chemistry. TIe now made the acquaintanee of Dr. Iteddoes. who had established a pneumatic institution at. Bristol. and who took him as his assistant. Here Davy •ar ried out a course of experiments the curative effeets of different gases, in which he had more than tune nearly saeriticed his life. Ile thus dis covered the singular exhilarating effect of nitrous oxide (laughing-gas). The which he published of his estahlished his repu tation, and led to his appointment. at the age of twenty-two. as lecturer at the Royal Institution of London. He delivered his first lecture in 1801, his eloquence, and the novelty and variety of exp(Timents, soon attracted large and audiences, In 1802 he was made fessor of chemistry at the Royal Institution. In he began researches connected with agri culture, and during ten years lectured before the Board of Agriculture on agricultural chem istry. His lectures were published in 1513, under the title of Elements of Agricultural Chemistry. The discoveries, however, on which Davy's fame as a chemist chiefly rests, took their origin in the views which he developed in 1806 in the Bakerian lecture, On Some Chemical ztgeneies of Electricity. This essay was universally regard ed as one of the most valuable contribution, ever made to chemical science, and obtained the prize of the French Institute. According to Davy. chemical affinity is nothing but the mutual electrical attraction of the ultimate particle; of matter, and chemical combination is caused by the equalization of electric potentials. Davy's electrolytic experiments led to the establish ment on a firm scientific basis of Lavoisier's idea that bases are compounds of oxygen with metals, and to the extension of this idea to caustic potash and soda, which Lavoisier hail regarded as ele ments. In 1807 Davy succeeded in decomposing potash. When he first saw the globules of the new metal potassium, his delight is said to have been so ecstatic that it required some time for him to compose himself before he was able to continue the experiments. He next decomposed
soda, strontia, and magnesia, and would have decomposed lime and baryta if he had not been prevented from doing so by a severe illness. dur ing which those alkaline earths were decomposed Uv Berzelius and Pontin. In 1509 he demonstrat ed the elementary nature of chlorine, and proved that hydrochloric acid is a compound of chlorine and hydrogen. It thus became clear that oxygen was not by any means an essential constituent of acids.
In 1812 Davy was knighted, married a lady of considerable wealth, and resigned the chemical chair of the Royal Institution. That he might investigate his new theory of volcanic action, he received permission from the Freneh Govern ment—though the two countries were then at war—to visit the Continent, and was received with the greatest distinction by the scientific men of France. On returning to England. in 1815. he entered on the investigation of the na ture of fire-damp. which is the cause of explo sions in coal-mines. This resulted in the inven tion of the safety lamp (q.v.)—one of the most valuable presents ever made by science to hu manity. Though the value of the invention was everywhere acknowledged. the only national re ward was a baronetcy after a lapse of three years. On the death of Sir Joseph Banks, in 1820. Sir Humphry Davy was elected presi dent of the Royal Society. His attention was shortly after called to the important object of preserving the copper sheathing of vessels from corrosion by the action of sea-water. This he effected by means of bands of zinc: lint the bot toms of the vessels became so foul from the ad hesion of weed:, etc., that the plan had to be abandoned.
in 1825 Sir Humphry Davy had begun to complain of the loss of strength. and in 1826 he had a paralytic attack affecting his right side. lie made two journeys to the Continent for the reeovel'y of his health. and died at Geneva on May 29, 1829, at the early age of fifty-one. The Genovese Government evinced their respect by a public funeral. So widely spread was the repu tation of Sir Humphry Davy that he was a mem ber of ahnok4, all the scientific institutions in the world. Cuvier. in his Efoge, says: "Mr. Davy, not yet fifty-two years of age. occupied. in the opinion of all that could judge of such labors, the first rank among the chemists of this or of any other age." Besides works already men tioned, and a great munber of to t he l'hilw.ophical Transactions, Sir published: Elemt.nis of Chemical Phi losophy London!, 1812). and Salmonia, or Days of Ply-•ishing. published in 1827. His ronsobt tions in Trurcl, or the Last Days of a Philoso (3d ed., London, 1531), appeared after his death. Consult: Memoirs of the Life of sir llumphry Duey, by hi, brother (2 vols., London, 1836). and The Lift' of Sir Ilumphry /tart', by Dr. Paris (London. 1831 ) . Spv. also, CHEMISTRY: and CIIEMISTRY, Al.RICULTURAL.