Davy, Sir Humphry


Davy, Sir Humphry (1778-1829), renowned British chemist, best known for his experiments in electrochemistry and for his invention of a miner's safety lamp.

Davy was born on December 17, 1778, in Penzance, Cornwall, England. In 1798 he began experiments on the medicinal properties of gases, during which he discovered the anesthetic effects of nitrous oxide (laughing gas). Davy was appointed assistant lecturer in chemistry at the newly founded Royal Institution in London in 1801 and the following year became professor of chemistry there.

During his early years at the Royal Institution, Davy started his investigations of the effects of electricity on chemical compounds. In 1807 he received the Napoleon Prize from the Institut de France for the theoretical and practical work begun the year before. He then constructed the largest battery ever built, with over 250 cells, and passed a strong electric current through solutions of various compounds suspected of containing undiscovered elements. Davy quickly isolated the elements potassium and sodium by this electrolytic method. He also prepared calcium by the same method. In later, unrelated experiments, he discovered boron and proved that the diamond is composed of carbon. Davy also showed that the so-called rare earths are oxides of metals rather than elements. His experiments with acids indicated that hydrogen, not oxygen, causes the characteristics of acids. Davy also made notable discoveries in heat.

In the field of applied science, Davy invented a safety lamp for miners in 1815. For this and for related research, he received the gold and the silver Rumford medals from the Royal Society. In 1823 he suggested a method of preventing the corrosion of the copper bottoms of ships by means of zinc and iron sheathing. He was knighted in 1812 and raised to a baronetcy in 1818. In 1820 he became president of the Royal Society. Davy died on May 29, 1829, in Geneva.

Among his writings are Elements of Chemical Philosophy (1812) and Elements of Agricultural Chemistry (1813).

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Davy, Sir Humphry, Baronet


b. Dec. 17, 1778, Penzance, Cornwall, Eng.


d. May 29, 1829, Geneva

English chemist who discovered several chemical elements (including sodium and potassium) and compounds, invented the miner's safety lamp, and became one of the greatest exponents of the scientific method.



Early life.


Davy was the elder son of middle-class parents, who owned an estate in Ludgvan. He was educated at the grammar school in nearby Penzance and, in 1793, at Truro. In 1795, a year after the death of his father, Robert, he was apprenticed to a surgeon and apothecary, and he hoped eventually to qualify in medicine. An exuberant, affectionate, and popular lad, of quick wit and lively imagination, he was fond of composing verses, sketching, making fireworks, fishing, shooting, and collecting minerals. He loved to wander, one pocket filled with fishing tackle and the other with rock specimens; he never lost his intense love of nature and, particularly, of mountain and water scenery.

While still a youth, ingenuous and somewhat impetuous, Davy had plans for a volume of poems, but he began the serious study of science in 1797, and these visions "fled before the voice of truth." He was befriended by Davies Giddy (later Gilbert; president of the Royal Society, 1827-30), who offered him the use of his library in Tradea and took him to a chemistry laboratory that was well equipped for that day. There he formed strongly independent views on topics of the moment, such as the nature of heat, light, and electricity and the chemical and physical doctrines of A.-L. Lavoisier. In his small private laboratory, he prepared and inhaled nitrous oxide (laughing gas), in order to test a claim that it was the "principle of contagion," that is, caused diseases. On Gilbert's recommendation, he was appointed (1798) chemical superintendent of the Pneumatic Institution, founded at Clifton to inquire into the possible therapeutic uses of various gases. Davy attacked the problem with characteristic enthusiasm, evincing an outstanding talent for experimental inquiry. He investigated the composition of the oxides and acids of nitrogen, as well as ammonia, and persuaded his scientific and literary friends, including Samuel Taylor Coleridge, Robert Southey, and P.M. Roget, to report the effects of inhaling nitrous oxide. He nearly lost his own life inhaling water gas, a mixture of hydrogen and carbon monoxide sometimes used as fuel. The account of his work, published as Researches, Chemical and Philosophical (1800), immediately established his reputation, and he was invited to lecture at the newly founded Royal Institution of Great Britain in London, where he moved in 1801, with the promise of help from the British-American scientist Sir Benjamin Thompson (Count von Rumford), the British naturalist Sir Joseph Banks, and the English chemist and physicist Henry Cavendish in furthering his researches; e.g., on voltaic cells, early forms of electric batteries. His carefully prepared and rehearsed lectures rapidly became important social functions and added greatly to the prestige of science and the institution. In 1802 he became professor of chemistry. His duties included a special study of tanning: he found catechu, the extract of a tropical plant, as effective as and cheaper than the usual oak extracts, and his published account was long used as a tanner's guide. In 1803 he was admitted a fellow of the Royal Society and an honorary member of the Dublin Society and delivered the first of an annual series of lectures before the board of agriculture. This led to his Elements of Agricultural Chemistry (1813), the only systematic work available for many years. For his researches on voltaic cells, tanning, and mineral analysis, he received the Copley Medal in 1805. He was elected secretary of the Royal Society in 1807.



Major discoveries.


Davy early concluded that the production of electricity in simple electrolytic cells resulted from chemical action and that chemical combination occurred between substances of opposite charge. He therefore reasoned that electrolysis, the interactions of electric currents with chemical compounds, offered the most likely means of decomposing all substances to their elements. These views were explained in 1806 in his lecture "On Some Chemical Agencies of Electricity," for which, despite the fact that England and France were at war, he received the Napoleon Prize from the Institut de France (1807). This work led directly to the isolation of sodium and potassium from their compounds (1807) and of the alkaline-earth metals from theirs (1808). He also discovered boron (by heating borax with potassium), hydrogen telluride, and hydrogen phosphide (phosphine). He showed the correct relation of chlorine to hydrochloric acid and the untenability of the earlier name (oxymuriatic acid) for chlorine; this negated Lavoisier's theory that all acids contained oxygen. He explained the bleaching action of chlorine (through its liberation of oxygen from water) and discovered two of its oxides (1811 and 1815), but his views on the nature of chlorine were disputed. He was not aware that chlorine is a chemical element, and experiments designed to reveal oxygen in chlorine failed.

In 1810 and 1811 he lectured to large audiences at Dublin (on agricultural chemistry, the elements of chemical philosophy, geology) and received 1,275 in fees, as well as the honorary degree of LL.D., from Trinity College. In 1812 he was knighted by the Prince Regent (April 8), delivered a farewell lecture to members of the Royal Institution (April 9), and married Jane Apreece, a wealthy widow well known in social and literary circles in England and Scotland (April 11). He also published the first part of the Elements of Chemical Philosophy, which contained much of his own work; his plan was too ambitious, however, and nothing further appeared. Its completion, according to a Swedish chemist, J.J. Berzelius, would have "advanced the science of chemistry a full century."

His last important act at the Royal Institution, of which he remained honorary professor, was to interview the young Michael Faraday, later to become one of England's great scientists, who became laboratory assistant there in 1813 and accompanied the Davys on a European tour (1813-15). By permission of Napoleon, he travelled through France, meeting many prominent scientists, and was presented to the empress Marie Louise. With the aid of a small portable laboratory and of various institutions in France and Italy, he investigated the substance "X" (later called iodine), whose properties and similarity to chlorine he quickly discovered; further work on various compounds of iodine and chlorine was done before he reached Rome. He also analyzed many specimens of classical pigments and proved that diamond is a form of carbon.



Later years.


Shortly after his return, he studied, for the Society for Preventing Accidents in Coal Mines, the conditions under which mixtures of firedamp and air explode. This led to the invention of the miner's safety lamp and to subsequent researches on flame, for which he received the Rumford medals (gold and silver) from the Royal Society and, from the northern mine owners, a service of plate (eventually sold to found the Davy Medal). After being created a baronet in 1818, he again went to Italy, inquiring into volcanic action and trying unsuccessfully to find a way of unrolling the papyri found at Herculaneum. In 1820 he became president of the Royal Society, a position he held until 1827. In 1823-25 he was associated with the politician and writer John Wilson Croker in founding the Athenaeum Club, of which he was an original trustee, and with the colonial governor Sir Thomas Stamford Raffles in founding the Zoological Society and in furthering the scheme for zoological gardens in Regent's Park, London (opened in 1828). During this period, he examined magnetic phenomena caused by electricity and electrochemical methods for preventing saltwater corrosion of copper sheathing on ships by means of iron and zinc plates. Though the protective principles were made clear, considerable fouling occurred, and the method's failure greatly vexed him. But he was, as he said, "burned out." His Bakerian lecture for 1826, "On the Relation of Electrical and Chemical Changes," contained his last known thoughts on electrochemistry and earned him the Royal Society's Royal Medal.

Davy's health was by then failing rapidly; in 1827 he departed for Europe and, in the summer, was forced to resign the presidency of the Royal Society, being succeeded by Davies Gilbert. Having to forgo business and field sports, Davy wrote Salmonia: or Days of Fly Fishing (1828), a book on fishing (after the manner of Izaak Walton) that contained engravings from his own drawings. After a last, short visit to England, he returned to Italy, settling at Rome in February 1829--"a ruin amongst ruins." Though partly paralyzed through stroke, he spent his last months writing a series of dialogues, published posthumously as Consolations in Travel, or the Last Days of a Philosopher (1830).





J.A. Paris, The Life of Sir Humphry Davy (1831), for more than a century the standard work on Davy's life; Sir H. Hartley, Humphry Davy (1966), an extremely useful account of Davy's life that complements Paris' biography but with changed emphases resulting from the passage of 135 years.