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Sir Humphrey Davy, Bart.

Born: 1778, Died: 1829

The son of a woodcarver, Davy was born in Penzance, in Cornwall, England, educated in Truro and then apprenticed to a Penzance surgeon-pharmacist. It was during his apprenticeship, where he learned of the work of the French chemist Lavoisier, that Davy became interested in chemistry.

After taking up the subject in 1897, he was taken on by Thomas Beddoes, as an assistant at Beddoes' Medical Pneumatic Institution in Bristol. Here Davy experimented with various new gases (probably contributing to his early death at the age of 51) and discovered the anaesthetic effect of laughing gas (nitrous oxide).

 

Sir Humphrey Davy, Bart.

Davy published details of his research in his book "Researches, Chemical and Philosophical" (1799), which led to Davy being appointed as a lecturer at the Royal Institution. He was a talented teacher and his lectures attracted large audiences - Royal Institution lectures became a fashionable alternative to the theatre!

In 1802 Davy co-operated with Thomas Wedgewood, the potter, on methods of transferring patterns to pots, described in "An Account of a Method of Copying Paintings on Glass, and Making Profiles, by the Agency of Light upon Nitrates of Silver". The production of silver chloride paper, later used in primitive photography, is described in the paper. Davy also mentions for the first time the registration of magnified images through a microscope, making him the inventor of photo-micrography.

He became a fellow of the Royal Society in 1803 and was awarded its prestigious Copley medal in 1805. In 1806 Davy published "On Some Chemical Agencies of Electricity", which marked one of his greatest contributions to science. In 1807 Davy discovered that the alkalis and alkaline earths are compound substances formed by oxygen united with metallic bases. Davy deduced that in a chemical substance the elements are held together by electric forces. His research into electrolysis led to the isolation of sodium, potassium, magnesium, calcium, strontium and barium. Besides these metals he also did research on chlorine and iodine.

Davy was now considered to be Britain's leading scientist and in 1812 was knighted by George III. With his assistant, Michael Faraday, Davy travelled abroad investigating his theory of volcanic action. In 1815 Davy received the request of a committee established to curb the devastating toll of mine explosions in the coal industry. Davy applied his talents to understanding methane ignitions in coal mines.

He discovered that, to explode, the gas must be heated to its ignition temperature and that if such heating is prevented combustion cannot occur. If the flame in a lamp is surrounded by metal gauze to distribute the heat over a large area, the maximum temperature of the screen is below the ignition temperature of the gas.

The first trial of a safety lamp with a wire gauze was at Hebburn Colliery on January 9, 1816. As well as providing a safer light than conventional candles, the safety lamp also provided a crude test for the presence of gases. If inflammable gas mixtures were present, the flame of the lamp burned higher and with a blue "cap".

Miners could also place a safety lamp close to the ground to detect gases, such as carbon dioxide, that are denser than air and so could collect in depressions in the mine; if the mine air was oxygen-poor (chokedamp), the lamp flame would be extinguished.

His invention sparked considerable controversy between the London establishment and the northern supporters of George Stephenson, who demonstrated another design of safety lamp in late 1815. Both men claimed the discovery, and the dispute soured their relationship. Neither man patented their ideas, allowing their designs to be used freely for the benefit of all miners.

One of Davy's most important contributions to history was that he encouraged manufacturers to take a scientific approach to production. His discoveries in chemistry helped to improve several industries including agriculture, mining and tanning. He was made Baronet in 1818, and in 1820 he became president of the Royal Society.

Davy pioneered the examination of the effects of various gases on humans. Much of what we know today, about the physiological effects of gases like nitrous oxide, carbon monoxide and carbon dioxide were discovered by Davy, who would seat himself in a large bell jar which his assistant would then fill with the gas in question. Davy would record the physical symptoms of exposure, often to the point of collapse, at which time he would have to be rescued and revived by his assistants. It is thought by many that these experiments lead to his ill-health in later life: he suffered a stroke in Rome in 1827, and he eventually died in Geneva on May 29th 1829.

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