Photographic enlargements In June 1802 Davy published in the first issue of the
Journals of the Royal Institution of Great Britain his
An Account of a Method of Copying Paintings upon Glass, and of Making Profiles, by the Agency of Light upon Nitrate of Silver. Invented by T. Wedgwood, Esq. With Observations by H. Davy in which he described their experiments with the photosensitivity of
silver nitrate. He recorded that "images of small objects, produced by means of the solar microscope, may be copied without difficulty on prepared paper."
Josef Maria Eder, in his
History of Photography, though crediting
Wedgwood, because of his application of this quality of silver nitrate to the making of images, as "the first photographer in the world," proposes that it was Davy who realised the idea of photographic
enlargement using a solar microscope to project images onto sensitised paper. Neither found a means of fixing their images, and Davy devoted no more of his time to furthering these early discoveries in photography. The principle of image projection using solar illumination was applied to the construction of the earliest form of photographic enlarger, the "
solar camera".
Elements metal, about 10 g, under oil metal crystals
Potassium and sodium Davy was a pioneer in the field of
electrolysis using the
voltaic pile to split common compounds and thus prepare many new elements. He went on to electrolyse molten salts and discovered several new metals, including
sodium and
potassium, highly reactive elements known as the
alkali metals. Davy discovered potassium in 1807, deriving it from
caustic potash (KOH). Before the 19th century, no distinction had been made between potassium and sodium. Potassium was the first metal that was isolated by electrolysis. Davy isolated sodium in the same year by passing an electric current through molten
sodium hydroxide. He noted that while these amalgams oxidised in only a few minutes when exposed to air they could be preserved for lengthy periods of time when submerged in
naphtha before becoming covered with a white crust. On 30 June 1808 Davy reported to the Royal Society that he had successfully isolated four new metals which he named
barium,
calcium,
strontium and magnium (later changed to
magnesium) which were subsequently published in the
Philosophical Transactions. Although Davy conceded magnium was an "undoubtedly objectionable" name he argued the more appropriate name magnesium was already being applied to metallic manganese and wished to avoid creating an equivocal term. The observations gathered from these experiments also led to Davy isolating
boron in 1809.
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." Davy performed a number of experiments aimed to isolate the metal
aluminium and is credited as the person who named the element. The first name proposed for the metal to be isolated from alum was
alumium, which Davy suggested in an 1808 article on his electrochemical research, published in
Philosophical Transactions of the Royal Society. It appeared that the name was created from the English word
alum and the Latin suffix
-ium; but it was customary then to give elements names originating in Latin, so this name was not adopted universally. This name was criticized by contemporary chemists from France, Germany, and Sweden, who insisted the metal should be named for the oxide, alumina, from which it would be isolated. The English name
alum does not come directly from Latin, whereas
alumine/
alumina comes from the Latin word
alumen (upon
declension,
alumen changes to
alumin-). The form aluminium, the modern preferred British word, was proposed by January 1811 in an account of Davy's published experiments written by William Hyde Wollaston. Davy later used aluminum (by 1812), which remains the U.S. word.
Chlorine Chlorine was discovered in 1774 by Swedish chemist
Carl Wilhelm Scheele, who called it
"dephlogisticated marine acid" (see
phlogiston theory) and mistakenly thought it contained
oxygen. Davy showed that the acid of Scheele's substance, called at the time
oxymuriatic acid, contained no
oxygen. This discovery overturned
Lavoisier's definition of acids as compounds of oxygen. The name chlorine, chosen by Davy for "one of [the substance's] obvious and characteristic properties – its colour", comes from the Greek χλωρος (chlōros), meaning green-yellow.
Laboratory incident Davy seriously injured himself in a laboratory accident with
nitrogen trichloride. French chemist
Pierre Louis Dulong had first prepared this compound in 1811, and had lost two fingers and an eye in two separate explosions with it. In a letter to
John Children, on 16 November 1812, Davy wrote: "It must be used with great caution. It is not safe to experiment upon a globule larger than a pin's head. I have been severely wounded by a piece scarcely bigger. My sight, however, I am informed, will not be injured". Davy's accident induced him to hire
Michael Faraday as a co-worker, particularly for assistance with handwriting and record keeping. They were both injured in another explosion shortly thereafter. He had recovered from his injuries by April 1813. Davy's party sailed from Plymouth to Morlaix by
cartel, where they were searched. While in Paris, Davy attended lectures at the
Ecole Polytechnique, including those by
Joseph Louis Gay-Lussac on a mysterious substance isolated by
Bernard Courtois. Davy wrote a paper for the Royal Society on the element, which is now called
iodine. This led to a dispute between Davy and Gay-Lussac on who had the priority on the research. They sojourned in
Florence, where using the
burning glass of the Grand Duke of Tuscany in a series of experiments conducted with Faraday's assistance, Davy succeeded in using the sun's rays to ignite
diamond, proving it is composed of pure
carbon. Davy's party continued to Rome, where he undertook experiments on iodine and chlorine and on the colours used in ancient paintings. This was the first chemical research on the pigments used by artists. Davy conceived of using an iron gauze to enclose a lamp's flame, and so prevent the methane burning inside the lamp from passing out to the general atmosphere. Although the idea of the
safety lamp had already been demonstrated by
William Reid Clanny and by the then unknown (but later very famous) engineer
George Stephenson, Davy's use of
wire gauze to prevent the spread of flame was used by many other inventors in their later designs. George Stephenson's lamp was very popular in the north-east coalfields, and used the same principle of preventing the flame reaching the general atmosphere, but by different means. Unfortunately, although the new design of gauze lamp initially did seem to offer protection, it gave much less light, and quickly deteriorated in the wet conditions of most pits. Rusting of the gauze quickly made the lamp unsafe, and the number of deaths from firedamp explosions rose yet further. There was some discussion as to whether Davy had discovered the principles behind his lamp without the help of the work of
Smithson Tennant, but it was generally agreed that the work of the two men had been independent. Davy refused to patent the lamp, and its invention led to his being awarded the
Rumford medal in 1816.
Acid studies In 1815 Davy also suggested that
acids were substances that contained replaceable
hydrogen ions;– hydrogen that could be partly or totally replaced by
reactive metals which are placed above hydrogen in the reactivity series. When acids reacted with metals they formed
salts and hydrogen gas.
Bases were substances that reacted with acids to form salts and water. These definitions worked well for most of the nineteenth century.
Herculaneum papyri Davy experimented on fragments of the Herculaneum papyri before his departure to Naples in 1818. His early experiments showed hope of success. In his report to the Royal Society Davy writes that: 'When a fragment of a brown
MS. in which the layers were strongly adhered, was placed in an atmosphere of chlorine, there was an immediate action, the papyrus smoked and became yellow, and the letters appeared much more distinct; and by the application of heat the layers separated from each other, giving fumes of
Hydrochloric acid (also known as
muriatic acid).' The success of the early trials prompted Davy to travel to Naples to conduct further research on the Herculaneum papyri. Accompanied by his wife, they set off on 26 May 1818 to stay in Flanders where Davy was invited by the coal miners to speak. They then traveled to Carniola (now Slovenia) which proved to become 'his favourite Alpine retreat' before finally arriving in Italy. In Italy, they befriended Lord Byron in Rome and then went on to travel to Naples. Initial experiments were again promising and his work resulted in 'partially unrolling 23 MSS., from which fragments of writing were obtained' but after returning to Naples on 1 December 1819 from a summer in the Alps, Davy complained that 'the Italians at the museum [were] no longer helpful but obstructive'. Davy decided to renounce further work on the papyri because 'the labour, in itself difficult and unpleasant, been made more so, by the conduct of the persons at the head of this department in the Museum'. == Later life: 1820–1829==