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Sir Humphry Davy
1778 - 1829
The English chemist and natural philosopher Sir Humphry Davy
isolated and named the elements of the alkaline-earth and alkali
metals and showed that chlorine and iodine were elements.
Humphry
Davy was born on Dec. 17, 1778, in Penzance, Cornwall. He was
apprenticed when he was 16 to an apothecary in Penzance, where
he evinced a great interest in chemistry and experimentation,
using as his guide Lavoisier's famous work, Traité élémentaire
de chimie. His obvious talents attracted the attention of
Gregory Watt and Davies Giddy (later Gilbert), both of whom
recommended him to Dr. Thomas Beddoes for the position of
superintendent of the newly founded Pneumatic Institution in
Bristol. He worked there from October 1799 to March 1801.
The Pneumatic Institution was investigating the idea that
certain diseases might be cured by the inhalation of gases.
Davy, sometimes perilously, inhaled many gases and found that
the respiration of nitrous oxide produced surprising results.
Inhalation of "laughing gas," as it was soon called, became a
novel form of entertainment, although nearly 50 years passed
before it was actually used as an anesthetic. Davy also
experimented with the newly invented voltaic pile, or battery.
Davy left Bristol to become the lecturer in chemistry at the
Royal Institution in London. Sir Joseph Banks and Count Rumford
had founded the Royal Institution in 1799 as a research
institute and as a place for educating young men in science and
mechanics. Here Davy's genius emerged fullblown. Not only did
his brilliant lectures attract a fashionable and intellectual
audience, but he also continued his electrical research. In 1806
he showed that there was a real connection between electrical
and chemical behaviour; for this achievement Napoleon I awarded
him a prize. In 1807 he electrolyzed molten potash and soda and
announced the isolation of two new elements, naming them
potassium and sodium. In 1808 he isolated and named calcium,
barium, strontium, and magnesium. Later he showed that boron,
aluminium, beryllium, and fluorine existed, although he was not
able to isolate them.
Lavoisier had claimed that a substance was an acid because it
contained oxygen. Davy doubted the validity of this claim and in
1810 showed that "oxymuriatic acid gas" was not the oxide of an
unknown element, murium, but a true element, which he named
chlorine.
In 1812 Davy married a wealthy widow, Jane Apreece, and was
knighted by the King for his great discoveries. Napoleon I
invited him to visit France, even though the two countries were
at war. Sir Humphry and his wife went to France in 1813, taking
with them as valet and chemical assistant the 22-year-old
Michael Faraday. The French presented them with a curious
substance isolated from sea-weed, and Davy, working in his hotel
room, was able to show that this was another new element,
iodine. When he returned to England, he was asked by a group of
clergymen to study the problem of providing illumination in coal
mines without exploding the methane there. Davy devised the
miner's safety lamp and gave the invention to the world without
attempting to patent or otherwise exploit it. Working in another
area, he demonstrated how electrochemical corrosion could be
prevented.
In 1820, after Sir Joseph Banks had died, Sir Humphry was made
president of the Royal Society. He began the needed internal
reform of the society, but bad health forced him to resign in
1827. The remaining years of his life he spent wandering about
the Continent in search of a cure for the strokes from which he
suffered. He died on May 29, 1829, in Geneva, Switzerland, where
he was buried.
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Sir Humphry Davy, 1st Baronet FRS MRIA (17 December 1778 – 29
May 1829) was a British chemist and inventor. He 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. He
invented the Davy lamp, which allowed miners to enter gassy
workings. 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.
Biography
Davy was born at Penzance in Cornwall on 17 December 1778. The
parish register of Madron (the parish church) records ‘Humphry
Davy, son of Robert Davy, baptized at Penzance, January 22nd,
1779.’ Robert Davy was a wood-carver at Penzance, who pursued
his art rather for amusement than profit. As the representative
of an old family (monuments to his ancestors in Ludgvan Church
date as far back as 1635), he became possessor of a modest
patrimony. His wife, Grace Millett, came of an old but no longer
wealthy family. Her parents died within a few hours of each
other from malignant fever, when Grace and her two sisters were
adopted by John Tonkin, an eminent surgeon in Penzance. Robert
Davy and his wife became the parents of five children—two boys,
Humphry, the eldest, and John, and three girls. In Davy's
childhood the family moved from Penzance to Varfell, their
family estate in Ludgvan. Davy's boyhood was spent partly with
his parents and partly with Tonkin, who placed him at a
preparatory school kept by a Mr. Bushell, who was so much struck
with the boy's progress that he persuaded the father to send him
to a better school. Davy was at an early age placed at the
Penzance grammar school, then under the care of the Rev. J. C.
Coryton. Numerous anecdotes show that Davy was a precocious boy,
possessing a remarkable memory and being singularly rapid in
acquiring knowledge of books. He was especially attracted by the
‘Pilgrim's Progress,’ and he delighted in reading history. When
but eight years of age he would collect a number of boys, and
standing on a cart in the market-place address them on the
subject of his latest reading. He delighted in the folklore of
this remote district, and became, as he himself tells us, a
‘tale-teller.’ The ‘applause of my companions,’ he says, ‘was my
recompense for punishments incurred for being idle.’ These
conditions developed a love of poetry and the composition of
verses and ballads.
At the same time Davy acquired a taste for experimental science.
This was mainly due to a member of the Society of Friends named
Robert Dunkin, a saddler and a man of original mind and of the
most varied acquirements. Dunkin constructed for himself an
electrical machine, voltaic piles, and Leyden jars, and made
models illustrative of the principles of mechanics. By the aid
of these appliances he instructed Davy in the rudiments of
science. As professor at the Royal Institution, Davy repeated
many of the ingenious experiments which he had learned from his
Quaker instructor. From the Penzance school Davy went in 1793 to
Truro, and finished his education under the Rev. Dr. Cardew,
who, in a letter to Davies Gilbert, says: ‘I could not discern
the faculties by which he was afterwards so much distinguished.’
Davy says himself: ‘I consider it fortunate I was left much to
myself as a child, and put upon no particular plan of study. …
What I am I made myself.’
Apprentice and poet
After the death of Davy's father in 1794, Tonkin apprenticed the
boy to John Bingham Borlase, a surgeon in large practice at
Penzance. Davy's indenture is dated 10 February 1795. In the
apothecary's dispensary Davy became a chemist, and a garret in
Tonkin's house was the scene of his earliest chemical
operations. Davy's friends would often say: ‘This boy Humphry is
incorrigible. He will blow us all into the air,’ and his eldest
sister complained of the ravages made on her dresses by
corrosive substances.
Much has been said of Davy as a poet, and John Ayrton Paris
somewhat hastily says that his verses ‘bear the stamp of lofty
genius.’ Davy's first production preserved bears the date of
1795. It is entitled ‘The Sons of Genius,’ and is marked by the
usual immaturity of youth. The poems, produced in the following
years, especially those ‘On the Mount's Bay’ and ‘St. Michael's
Mount,’ are pleasingly descriptive verses, showing sensibility,
but no true poetic imagination. Davy soon abandoned poetry for
science. While writing verses at the age of seventeen in honour
of his first love, he was eagerly discussing with his Quaker
friend the question of the materiality of heat. Dunkin once
remarked: ‘I tell thee what, Humphry, thou art the most
quibbling hand at a dispute I ever met with in my life.’ One
winter day he took Dunkin to Larigan river, to show him that the
rubbing of two plates of ice together developed sufficient
energy by motion to melt them, and that the motion being
suspended the pieces were united by regelation. This was, in a
rude form, an elementary version of an analogous experiment
later exhibited by Davy in the lecture-room of the Royal
Institution, which excited considerable attention.
Early scientific leanings
Davies Giddy, afterwards Davies Gilbert, accidentally saw Davy
in Penzance, carelessly swinging on the half-gate of Dr.
Borlase's house. Gilbert was interested by the lad's talk,
offered him the use of his library, and invited him to his house
at Tredrea. This led to an introduction to Dr. Edwards, who then
resided at Hayle Copper House, and was also chemical lecturer in
the school of St. Bartholomew's Hospital. Dr. Edwards permitted
Davy to use the apparatus in his laboratory, and appears to have
directed his attention to the floodgates of the port of Hayle,
which were rapidly decaying from the contact of copper and iron
under the influence of seawater. This galvanic action was not
then understood, but the phenomenon prepared the mind of Davy
for his experiments on the copper sheathing of ships in later
days. Gregory Watt, the son of James Watt, visited Penzance for
his health's sake, and lodging at Mrs. Davy's house became a
friend of her son and gave him instructions in chemistry. Davy
also formed a useful acquaintance with the Wedgwoods, who spent
a winter at Penzance.
Thomas Beddoes and Professor Hailstone were engaged in a
geological controversy upon the rival merits of the Plutonian
and the Neptunist hypotheses. They travelled together to examine
the Cornish coast accompanied by Davies Gilbert, and thus made
Davy's acquaintance. Beddoes, who had recently established at
Bristol a ‘Pneumatic Institution,’ required an assistant to
superintend the laboratory. Gilbert recommended Davy for the
post, and Gregory Watt placed (in April 1798) in the hands of
Beddoes the ‘Young man's Researches on Heat and Light,’ which
were subsequently published by him in the first volume of
‘West-Country Contributions.’ Prolonged negotiations were
carried on, mainly by Gilbert. Mrs. Davy and Borlase consented
to Davy's departure, but Tonkin desired to fix him in his native
town as a surgeon, and actually altered his will when he found
that Davy insisted on going to Dr. Beddoes.
The Pneumatic Institution
On 2 October 1798 Davy joined the ‘Pneumatic Institution’ at
Bristol. This institution was established for the purpose of
investigating the medical powers of factitious airs and gases,
and to Davy was committed the superintendence of the various
experiments. The arrangement concluded between Dr. Beddoes and
Davy was a liberal one, and enabled Davy to give up all claims
upon his paternal property in favour of his mother. He did not
intend to abandon the profession of medicine, being still
determined to study and graduate at Edinburgh. However, he soon
found his whole energies absorbed in the labours of the
laboratory. During his residence at Bristol, Davy formed the
acquaintance of the Earl of Durham, who became a resident for
his health in the Pneumatic Institution, and of Samuel Taylor
Coleridge and Robert Southey. In December 1799 Davy visited
London for the first time, and his circle of friends was there
much extended.
In this year the first volume of the ‘West-Country Collections’
was issued. Half of the volume consisted of Davy's essays ‘On
Heat, Light, and the Combinations of Light,’ ‘On Phos-oxygen and
its Combinations,’ and on the ‘Theory of Respiration.’ On 22
February 1799 Davy, writing to Davies Gilbert, says: ‘I am now
as much convinced of the non-existence of caloric as I am of the
existence of light.’ In another letter written to Davies
Gilbert, on 10 April, Davy informs him: I made a discovery
yesterday which proves how necessary it is to repeat
experiments. The gaseous oxide of azote (the laughing gas) is
perfectly respirable when pure. It is never deleterious but when
it contains nitrous gas. I have found a mode of making it pure.’
He then says that he breathed sixteen quarts of it for nearly
seven minutes, and that it ‘absolutely intoxicated me.’ During
this year Davy published his ‘Researches, Chemical and
Philosophical, chiefly concerning Nitrous Oxide and its
Respiration.’ In after years Davy regretted that he had ever
published these immature hypotheses, which he himself
subsequently designated as ‘the dreams of misemployed genius
which the light of experiment and observation has never
conducted to truth.’
The Royal Institution
A satirical cartoon by James Gillray showing a Royal Institution
lecture on pneumatics with Humphrey Davy holding the bellows and
Count Rumford looking on at extreme right. Dr Garnett is the
lecturer holding the victim's nose
In 1800 Davy informed Davies Gilbert that he had been ‘repeating
the galvanic experiments with success’ in the intervals of the
experiments on the gases, which ‘almost incessantly occupied him
from January to April.’ In these experiments Davy ran
considerable risks. The respiration of nitrous oxide led, by its
union with common air in the mouth, to the formation of nitrous
acid, which severely injured the mucous membrane, and in his
attempt to breathe carburetted hydrogen gas he ‘seemed sinking
into annihilation.’ On being removed into the open air he
faintly articulated, ‘I do not think I shall die,’ but some
hours elapsed before the painful symptoms ceased. It is likely
that the nitrous oxide he inhaled was contaminated by nitric
oxide, a toxic gas which combines with oxygen to form nitric
acid, a very strong acid and irritant, which explains the pain
he felt.
Davy's ‘Researches,’ which was full of striking and novel facts,
and rich in chemical discoveries, soon attracted the attention
of the scientific world, and Davy now made his grand move in
life. In 1799 Count Rumford had proposed the establishment in
London of an ‘Institution for Diffusing Knowledge,’ i.e. the
Royal Institution. The house in Albemarle Street was bought in
April 1799. Rumford became secretary to the institution, and Dr.
Garnett was the first lecturer. Garnett was forced to resign
from ill-health in 1801. Rumford had already been empowered to
treat with Davy. Personal interviews followed, and on 15 July
1801 it was resolved by the managers ‘that Humphry Davy be
engaged in the service of the Royal Institution in the capacity
of assistant lecturer in chemistry, director of the chemical
laboratory, and assistant editor of the journals of the
institution, and that he be allowed to occupy a room in the
house, and be furnished with coals and candles, and that he be
paid a salary of 100l. per annum.’ 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.
Electrolysis
Davy was a pioneer in the field of electrolysis using the
battery to split up common compounds and thus prepare many new
elements. He went on to electrolyse molten salts and discovered
several new metals, especially sodium and potassium, highly
reactive elements known as the alkali metals. Potassium was
discovered in 1807 by Davy, who derived it from caustic potash (KOH).
Before the 18th century, no distinction was made between
potassium and sodium. Potassium was the first metal that was
isolated by electrolysis. Sodium was first isolated by Davy in
the same year by passing an electric current through molten
sodium hydroxide. Sodium quickly oxidizes in air and is
violently reactive with water, so it must be stored in an inert
medium, such as kerosene. Sodium is present in great quantities
in the earth's oceans as sodium chloride (common salt). Davy
went on to discover calcium in 1808 by electrolyzing a mixture
of lime and mercuric oxide. Davy was trying to isolate calcium;
when he heard that Berzelius and Pontin prepared calcium amalgam
by electrolyzing lime in mercury, he tried it himself. He worked
with electrolysis throughout his life and also discovered
magnesium, boron and barium.
Discovery of 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.
Scheele produced chlorine by reacting manganese dioxide (MnO2)
with hydrogen chloride (HCl).
4 HCl + MnO2 → MnCl2 + 2 H2O + Cl2
Scheele observed several properties of chlorine gas, such as its
bleaching effect on litmus, its deadly effect on insects, its
yellow-green colour, and the similarity of its smell to that of
aqua regia. However, Scheele was unable to publish his findings
at the time.
In 1810, chlorine was given its current name by Humphry Davy,
who insisted that chlorine was in fact an element. He also
showed that oxygen could not be obtained from the substance
known as oxymuriatic acid (HCl solution). This discovery
overturned Lavoisier's definition of acids as compounds of
oxygen.
Popular public figure
Sir Humphry revelled in his public status, as his lectures
gathered many spectators. He 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. Pierre Louis Dulong first prepared this
compound in 1812, and lost two fingers and an eye in two
separate explosions with it. Davy's own accident induced him to
hire Michael Faraday as a coworker.
Work
In 1812, Davy 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. While
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 in December 1813, travelling south to
Italy. They sojourned in Florence, where, 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, and
also visited Naples and Mount Vesuvius. By June 1814, they were
in Milan, where they met Alessandro Volta, and then continued
north to Geneva. They returned to Italy via Munich and
Innsbruck, and when their plans to travel to Greece and
Constantinople (Istanbul) were abandoned after Napoleon's escape
from Elba, they returned to England.
In January 1819, Davy was awarded a baronetcy, at the time the
highest honour ever conferred on a man of science in Britain. A
year later he became President of the Royal Society.
The Davy lamp
After his return to England in 1815, Davy experimented with
lamps for use in coal mines. There had been many mining
explosions caused by firedamp or methane often ignited by open
flames of the lamps then used by miners. In particular the
Felling mine disaster in 1812 near Newcastle caused great loss
of life, and action was needed to improve underground lighting
and especially the lamps used by miners. 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 copied by other
inventors in their later designs. Unfortunately, although the
new design initially did seem to offer protection, it gave 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
both men had been independent. Davy refused to patent the lamp,
and its invention led to him being awarded the Rumford medal in
1816.
Acid-base studies
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
nineteenth century.
Death
Davy's grave, Plot 208, Plainpalais Cemetery, Rue des Rois,
Geneva.
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 he became the more famous and
influential scientist – to the extent that Davy is supposed to
have claimed Faraday as his greatest discovery. However, Davy
later accused Faraday of plagiarism, causing Faraday (the first
Fullerian Professor of Chemistry) to cease all research in
electromagnetism until his mentor's death.
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