Sir Humphry Davy, 1st Baronet, FRS (17 December 1778 – 29 May 1829) was a British chemist and physicist. He was born in Penzance, Cornwall and both his brother John Davy and cousin Edmund Davy were also noted chemists.
At six years of age young Davy was adopted and taken from his parents by a surgeon, Mr. Tonkin, who resided about three miles from Penzance. Mr. Tonkin was a respectable old gentleman, who wore a full-bottomed wig, a three-cornered hat, and silver shoe-buckles. Davy had a quiet life with him, the only notable incident being that one day he was taken to listen to the preaching of the famed John Wesley who after the service was over, patted the youth on the head, with the remark, "God bless you, my dear boy." He afterwards went for a short time to a school managed by Dr. Cardew
1795 Next he was apprenticed to Mr. Borlase, an apothecary, Mr. Tonkin paying sixty guineas premium on the occasion. During his apprenticeship be first began seriously to study the works of nature, and made some investigations respecting the respiration of fishes. He also tried his hand at poetry, an "Ode to the Moon" being of course, among the earliest of these compositions followed by poems entitled "The Tempest," and the sons of Genius." The following is an extract from one of his poems, showing also the bent of his mind at this period :-
" Oh most magnificent and noble Nature! Have I not worshipped thee with such a love As never mortal man before displayed? Adored thee in thy majesty of visible creation, And searched into thy hidden and mysterious ways, As poet, and philosopher, and sage?"
c.1798 Davy became interested in the properties of nitrous oxide, and experimented on himself by breathing in the gas
In 1801 he was nominated professor at the Royal Institution of Great Britain and Fellow of the Royal Society, over which he would later preside. He later invented the Davy lamp which was a great and well-known success.
Berzelius called Davy's 1806 Bakerian Lecture "On Some Chemical Agencies of Electricity" "one of the best memoirs which has ever enriched the theory of chemistry." This paper was central to any chemical affinity theory in the first half of the nineteenth century. Davy is probably best remembered today for his discoveries of several alkali and alkaline-earth elements, as well as contributions to the discoveries of the elemental nature of chlorine and iodine.
Sir Humphry revelled in his status, as his lectures gathered many spectators. Davy became well known due to his experiments with the physiological action of some gases, including laughing gas (nitrous oxide) - to which he was addicted, once stating that its properties bestowed all of the benefits of alcohol but was devoid of its flaws. Davy later damaged his eyesight in a laboratory accident with nitrogen trichloride.
In 1812 he was knighted, gave a farewell lecture to the Royal Institution, and married a wealthy widow, Jane Apreece. While generally acknowledged as being faithful to his wife, their relationship was stormy and in his later years Davy travelled to continental Europe alone. In October 1813 he and his wife, accompanied by Michael Faraday as his scientific assistant (and valet) travelled to France to collect a medal that Napoleon Bonaparte had awarded Davy for his electro-chemical work. Whilst in Paris Davy was asked by Gay-Lussac to investigate a mysterious substance isolated by Bernard Courtois. Davy showed it to be an element, which is now called iodine. The party left Paris on December 29, travelling south through Montpellier and Nice and then to Italy.
After passing through Genoa, they went to Florence, where, in a series of experiments starting on Sunday March 27, Davy, with Faraday's assistance, succeeded in using the sun's rays to ignite diamond, and proved that it was composed of pure carbon. Davy's party continued on to Rome, and also visited Naples and Mount Vesuvius. By the June 17, they were in Milan, where they met Alessandro Volta, and continued north to Geneva. They returned to Italy via Munich and Innsbruck, passed though Venice and returned to Rome. Their plans to travel to Greece and Constantinople (Istanbul) were abandoned after Napoleon's escape from Elba, and they returned to England.
After his return to England in 1815, Davy went on to produce the Davy lamp which was widely used by miners. Although the idea of the safety lamp had already been demonstrated by William Reid Clanny and an engineer, George Stephenson, his use of wire gauze to prevent the spread of flame was quickly copied by both of these inventors in their later designs.
He also showed that oxygen could not be obtained from the substance known as oxymuriatic acid and proved the substance to be an element, which he named chlorine. (However Carl Scheele is credited as the discoverer of chlorine. Scheele had discovered it 36 years before Davy, but was unable to publish his findings.) This discovery overturned Lavoisier's definition of acids as compounds of oxygen.
In 1815 Davy suggested that acids were substances that contained replaceable hydrogen – hydrogen that could be partly or totally replaced by metals. When acids reacted with metals they formed salts. Bases were substances that reacted with acids to form salts and water. These definitions worked well for most of the century. Today we use the Brønsted-Lowry theory of acids and bases.
In 1818, he was awarded a baronetcy, and two years later he became President of the Royal Society.
1824 'On the Corrosion of Copper Sheeting' 
Davy died in Switzerland in 1829, his various inhalations of chemicals finally taking their toll on his health. He is buried in the Plain Palais Cemetery in Geneva.
Davy's laboratory assistant, Michael Faraday, went on to enhance Davy's work and in the end became more famous and influential – to such an extent that Davy is supposed to have claimed Faraday as his greatest discovery. However, he later accused Faraday of plagiarism, causing Faraday (the first Fullerian Professor of Chemistry) to cease all research in electromagnetism until his mentor's death.
Sources of Information
-  Wikipedia