DAVY, Sir Humm o inv, ne of the greatest chemists of his own or of any age, was b. on the 17th Dec., 1778, at Penzance, in Cornwall, where his father was a carver in wood. At the school of Truro, where he was educated until he was 15, he showed lit tle relish for classical learning, but be was distinguished for a highly retentive memory and an early passion for poetry, which never forsook him. Another prominent trait of his character was equally early developed: as a child, be would angle even in the gut ters of the streets; and only two years before his death, and after his health had given way, he published his interesting volume, Salmonia, or Days of Fly-fishing. Soon after leaving-school, he became apprentice to a surgeon and apothecary in Penzance. He at the same time entered upon a course of study all but universal. " Speculations on religion and politics, on metaphysics and morals, arc placed in his note-books in juxta position with stanzas of poetry and fragmeats of romance." A system of mathematical study, skeptical philosophy, Scotch metaphysics, and German transcendentalism, suc cessively engaged his attention. The study of natural philosophy brought him nearer to that department which was to be his own; but it was not till he had reached his 19th year, that he entered seriously upon the study of chemistry. He now made the acquaintance of Dr. Beddoes, who had established a pneumatic institution at Clifton, and who took him as his assistant. Here D. carried on a course of experiments on the respiration of different gases, in which he had more than once nearly sacrificed his life. He thus discovered the singular exhilarating effect of nitrous oxide when breathed. The account which he published of his researches, established his reputation, and led to his appointment, at the age of 22, as lecturer to the royal institution of London. He delivered his first lecture in 1801; and his eloquence, and the novelty and variety of his experiments, soon attracted crowded and brilliant audiences. In 1803, lie began researches connected with agriculture, on which he delivered a course of lectures. These were published in 1813, under the title of Elements of .Agricultural Chemistry, and form an era in that science. The discoveries, however, on which D.'s fame as a clienF ist chiefly rests, took their origin in the views which he developed in 1806, in his Baker ian lecture, On Some Chemma Agencies of Electricity. This essay was universally regarded as one of the most valuable contributions ever made to chemical science, and obtained the prize of the French institute. Following out his principle, he was led to the grand discovery, that the alkalies and earths are compound substances, formed by oxygen united with metallic bases. It was potash that he first succeeded in decom posing, on the 8th Oct., 1807. When lie first saw the globules of the new metal, potas >him, his delight is'said to have been so ecstatic that it required some time for him to compose himself to continue the experiment. He next decomposed soda and the alka.
line earths, baryta, strontia, lime, and magnesia; and discovered the new metals, sodium, barium, strontium, calcium, and magnesium. 'With regard to the earths proper, he suc seeded in proving that they consist of bases united to Oxygen. It was reserved for Wahler and others to exhibit the bases by themselves.
In 1812, D. was knighted, married a lady of considerable wealth, and resigned tho chemical chair of the royal institution. That lie might investigate his new theory of volcanic action, he received permission from the French government—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 nature of tire-damp, which is the cause of explosions in coal mines. This resulted in the invention of the safety-lamp (q.v.)—one of the most valuable presents ever made by science to humanity. Though the value of the inven tion was everywhere acknowledged, the only national reward was a baronetcy after a lapse of three years. This has been contrasted with the pension of £1200 a year bestowed by the same government on sir William Congreve, for the invention of his rocket. On the death of sir Joseph Banks, in 1820, sir IIumphry D. 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 altering the electric condition of the copper by means of bands of zinc; but the bottoms of the vessels became so foul from the adhesion of weeds, shells, etc.. that the plan had to be abandoned.
Early in 1825, sir Humphry D. had begun to complain of the loss of strength, and, in 1826, lie bad a paralytic attack affecting his right side. He made two journeys to the continent for the recovery of his health, and died at Geneva on the 29th May, 1829, at the early age of 51. The Genevese government evinced their respect by a public funeral. So widely spread was the reputation of sir Humphry D., that he was a member of almost all the scientific institutions in the world. Cuvier, in his Eloge, says: "Mr. Davy, not yet 52 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 the works already mentioned, and a great number of contributions to the Philosophical Transactions, sir Humphry D. published Elements of Chemical Philosophy (Loud. 1812); and Consolations in Travel, or the Last Days of a Philosopher (3d ed., Lond. 1831), appeared after his death. See 1kmoirs of the Life of sir Humphry D., by his brother (Load. 1836, 2 vols.); and The Life of Sir Humphry D., by Dr. Paris (Loud. 1831).