Scientific Revolution
The Scientific Revolution is a term commonly
referring to the transformation of thought
about nature through which the Aristotelian
tradition was replaced by so-called "modern"
science.
Chemical Revolution
• The Greek philosopher Democritus
began the search for a description
of matter more than 2400 years
ago.
• He asked: Could matter be divided
into smaller and smaller pieces
forever, or was there a limit to the
number of times a piece of matter
could be divided?
The Greek Philosopher Democritus
Democritus
c. 460 – c. 370 BC
Atomos
• His theory: Matter could not be
divided into smaller and smaller
pieces forever, eventually the smallest
possible piece would be obtained.
• This piece would be indivisible.
• He named the smallest piece of matter
“atomos,” meaning “can not be cut.”
Democritus
Atomos
§To Democritus, atoms were small, hard
particles that were all made of the same
material but were different shapes and sizes.
§Atoms were infinite in number, always
moving and capable of joining together.
The four elements of ancient times (Greek)
• All matter is made up of these four elements
• The above four elements are transmutable
Five interconvertible elements make up the earth
Pancha Bhoota (Sanskrit: प"चभूत), five great elements, which, according to
Hinduism, is the basis of all cosmic creation.
• Prithvi (Sanskrit: पृ+वी:, Earth),
• Jal (Sanskrit: अप:, Water),
• Agni (Sanskrit: अि1न, Fire),
• Vayu (Sanskrit: वायु:, Air),
• Akasha (Sanskrit: आकाश, Space ).
The Indian View
(Taittirīya Upanishad and Aitareya Upanishad, 6th century BC)
Even before Aristotle
Kashyap (Acharya Kanada)
• Vaisheshika school of philosophy
• Vaisheshika Sutras
• 6th century BC
Ancient Indian Atomistic Thoughts
Every object of creation is made of atoms (paramāṇu) which in
turn connect with each other to form molecules (aṇu). Atoms
are eternal, and their combinations constitute the empirical
material world.
The similarity of the early Indian views of matter with the Greek models have led historians
to wonder if communication occurred between the philosophers in these early civilizations.
The Greek Philosopher Aristotle
• Believed that matter could be
continuously divided without end
(the “continuous” idea of matter).
• There is no need for empty space.
• There are no atoms. All matter is
made of the natural elements
(earth, water, air and fire.
384-322 BC
Alchemy (next 1500 years)
• Mixture of science and mysticism.
• Lab procedures were developed, but alchemists did not
perform controlled experiments like true scientists.
European and Asian philosophers
Alchemists
Phlogistonists
Modern chemists
The Aristotelian tradition and medieval alchemy
eventually gave rise to modern chemistry
Ancient Greeks:
5th century BC to 17th century Earth, Water, Air and Fire
Asians:
5th century BC to 17th century Earth, Water, Air, Fire and Space
Middle Eastern: Abu Mus-Hayyan
8th century AD Elements + sulfur + mercury
European: Paracelsus (Swiss alchemist)
16th century AD Elements + {sulfur + mercury+salt}
Alchemists to Phlogistonists
Alchemists laid the groundwork for many chemical processes, such as the refining of ores,
the production of gunpowder, the manufacture of glass and ceramics, leather tanning, and
the production of inks, dyes, and paints. Alchemists also made the first attempts at
organizing and classifying substances so that they could better understand their reactions
and be able to predict the products of their experiments.
Alchemists
300 BC to 17th century
• Transmutation of metals
• Philosophers stone
• Elixir of life
• Interconversion of minerals
• Looking for medicines
Alchemists attempted to transmute
cheap metals to gold. The substance
used for this conversion was called
the Philosopher's Stone.
Arabian origin but was prevalent world over
Alchemists: Middle-East, Greeks, Romans, Asia, Europe
300 BC-17th century
Johann Joachim Becher Replaced Greek and Paracelsus (Swiss
1635 – 1682 alchemist) elements (4+3) with two,
Seven elements became two: earth and water,
air used only as a mixer.
Proposed that when a substance burned, a
combustible earth was liberated.
Georg Ernst Stahl Kept the proposals of Becher except changed
1659-1734 the name of flammable earth to phlogiston.
Beginnings of Phlogistonists
According to the phlogiston theory a colorless, odorless and
weightless substance called phlogiston, present in every material
was released while it burnt and the ‘ash’ that remained was
considered as ‘dephlogisticated’ material.
Phlogiston Theory
17 & 18th centuries
Georg Ernst Stahl
1659-1734
Johann Joachim Becher
1635 – 1682
In addition to air, earth, water and fire, the materials contain phlogiston.
NOW: Fire is a chemical reaction that converts a fuel and oxygen into
carbon dioxide and water.
What is fire?
THEN: Release of phlogiston is the definition of burning. The flame
indicates the rapid escape of phlogiston.
Questions about Combustion
• In early 18th Century, an attempt was made to
understand combustion (burning, fire).
• Why do some materials burn, while others don’t?
• When a piece of wood burned, it turned into ash
with much less mass than the original wood.
• What happens to the rest of the wood mass?
• All combustible substances contain phlogiston.
• Non-combustible substances do not contain
phlogiston.
• The more phlogiston a substance contains, the
better and more completely it burns.
• When wood burns there is a decrease in weight.
• Release of phlogiston results in weight loss.
Basics of phlogiston theory
• Air is necessary for combustion because it absorbs the
escaping phlogiston.
• The air becomes saturated with phlogiston – it
becomes phlogisticated air.
• When a candle burns in a closed jar, it burns for a
while before the flame goes out; this is because the air
in the jar is saturated with phlogiston.
• Observation: Combustion does not occur in a vacuum.
• Explanation: There was no air present to carry off the
phlogiston.
Where is phlogiston going upon burning?
Phlogiston Theory explained why things stopped
burning
Phlogiston theory of burning. (A)
When an object burns, it gives off
a substance calledphlogiston. (B)
When the space surrounding the
burning object is filled with
phlogiston, the object will no
longer be able to burn.
(A)
phlogiston
Do you support or refute the hypothesis?
Modern theory of burning
• When an object burns, it uses up a substance (oxygen) in
the surrounding space.
• When the space surrounding the burning object has too
little oxygen in it, the object will no longer be able to burn.
Metals don’t burn but get rusted
Metal to metal calx
W
Wood Ash + Phlogiston
Metal Calx + Phlogiston
• Typically, metal calx weighed more than the
original metal.
• How can this be if the calcification process
drives off the phlogiston in the metal?
• Answer: Phlogiston possesses levity; i.e., it is
lighter than nothing; it has negative weight (?)
Fire to Rust: Minor hitch in the theory
Levity is an ancient idea
• Levity, or inherent lightness, is an idea invented by
Aristotle.
• Air and fire rise because they possess levity, while earth
and water fall because they possess heaviness.
• These are qualitative notions. They do not fit in
quantitative, mechanist explanations.
The logic of phlogiston
https://edu.rsc.org/feature/the-logic-of-phlogiston/2000126.article
Place an empty balloon, about 10 cm of string and a few centimetres of sticky tape on a toppan
balance.
Tare the balance to read zero.
Fill the balloon with ‘phlogiston’ (flamable hydrogen), tie the neck and tape it down onto the
balance pan.
The balance will now show a negative reading; ie the mass of phlogiston added to the balloon
is negative.
Metal calx to metal
Metal calx are powders, like ash, resulting from heating metals in a fire.
Mercury Mercury calx + phlogiston
Stahl’s idea was that phlogiston was driven out of the metal when the calx
was produced.
Mercury reacts with oxygen to form mercuric oxide
Mercury calx + Phlogiston Mercury
Charcoal
If calx is reheated in an oven filled with charcoal the calx turned back into
the original metal.
An excellent source of phlogiston is charcoal, which therefore could
reconvert a calx to its metal.
Charcoal absorbs the released oxygen and reacts to form carbon dioxide
Dephlogisticated air
• Joseph Priestley produced different gases by
performing chemical reactions and collecting the
gases produced with a pneumatic trough.
• He produced a new gas by heating mercuric calx
by concentrating the sun’s rays on it.
Joseph Priestley
1733 – 1804
Mercury calx + Phlogiston Mercury
Air
Left out air “dephlogisticated air”
No charcoal
Priestley declared: "I could not doubt but that the calx was actually
imbibing something from the air; and from its effects in making the calx
into metal, it could be no other than that to which chemists had
unanimously given the name of phlogiston."
Dephlogisticated air
Dephlogisticated air
• Mercury calx + Phlogiston Mercury
Air
• According to phlogiston theory, he was reimpregnating
the mercury calx with
phlogiston, taken from the surrounding air.
• Hence, the air that remained was deficient in
phlogiston. He called it “dephlogisticated
air”.
• Earlier charcoal was used instead of air as a
source of phlogiston.
Dephlogisticated air
• Experimenting with his new air, Priestley found that:
• A candle burned brighter in it.
• A mouse put in a closed flask of the air lived longer
than one in a flask with ordinary air.
• He tried breathing it himself, and it made him feel
great.
All air are not the same
Parallel to phlogiston theory, another concept entered chemistry
about the same time: the notion of “air” and that “air” is not just
one thing, but that there are different kinds of air (many many
air?)”
Stephen Hales
(1677 –1761)
Pneumatic troughs
Hales’s Priestly’s
New air(s)
• Joseph Black identified several
new gases, giving them names
consistent with phlogiston theory.
• “fixed air,”
carbon dioxide
• Other researchers identified other
new “airs.”
• “flammable air”
hydrogen
Joseph Black
1728-1799
Antoine Lavoisier
The Father of Modern Chemistry
1743–1794
https://www.youtube.com/watch?v=AE0
kuHKoitE
http://mysteryofmatter.net/Lavoisier.html
• Four elements theory is accepted for want of a better one.
• Boyle’s definition of element did not get accepted; so, fire, water, air and
earth are still the basic elements.
• The phlogiston theory dominated chemical philosophy.
• The composition of air and water unknown.
• Hydrogen and oxygen are yet to be discovered.
• The mechanism of respiration and metabolism understood in the context of
phlogiston.
Status of chemistry during the lifetime of Lavoisier (1743–1794)
Some materials burn because they contain phlogiston.
Phlogiston is released into the air when material burns.
Major flaw…some materials weigh more after they are
burnt.
Wood à Ashes + Phlogiston; ashes weigh less…okay…
But…Iron à Rust + Phlogiston; rust weighed more than
the iron
Lavoisier noticed the inconsistencies of the phlogiston
theory and came up with a better explanation of
combustion.
Phlogiston Theory – no longer valid!
• Established concepts as needed.
• Performed quantitative experiments to study
chemical reactions, including combustion
process.
• Built a self-financed well-equipped laboratory.
Lavoisier saw the opportunity
• Invented and invested on new instruments: a
burner that used ‘amplified Sunlight’ (heater),
calorimeter, analytical balances, etc.
Ø In 1768, at a young age of 25, he accepted office as a
Farmer–General of Taxes, and as a chemist at the Royal
Academy of Sciences, the most elite science society.
Ø Accepting Farmer-General of Taxes; he used his income to
finance his experiments.
Ø A few years later he married the daughter of another tax
farmer, Marie Anne who was only 13 at the time.
Ø Antoine Lavoisier was appointed regional inspector for the
Tobacco Commission.
Ø Lavoisier became an important landowner by successive
acquisition of land, in 1778.
Personal Life of Lavoisier
She also translated her
husband’s work from French
into English so he could share
his ideas.
Her sketching skills were
used to produce engravings
of the apparatus and methods
he used.
Marie-Anne would translate
these English papers into
French for her husband to be
able to understand them
Madam Lavoisier
Home built laboratory equipments
Helped to make sketches and take notes. She has drawn herself taking
notes at the right-hand table.
Married Marie-Anne in 1771
Lavoisier’s ideas
• Lavoisier viewed heat as one of the elements,
“caloric.”
• Air he thought was a compound of different
substances.
• He thought that Priestley’s “dephlogisticated air”
was actually an element.
Lavoisier’s classic experiment-1
• Lavoisier took mercury
and a measured volume
of air and heated them
together.
• This produced a
mercuric calx and
reduced the volume of
the air.
Lavoisier’s classic experiment-2
• He then reheated the mercuric calx by itself at a
lower temperature and saw it go back to mercury.
• In the process it produced a gas, equal in volume to
the amount lost from the first procedure.
Lavoisier’s classic experiment-3
• Observation: water is raising in the tube indicating the
amount of air decreasing as mercury goes to calx
• Lavoisier concluded that instead of the original heating
driving off phlogiston from the mercury, the mercury was
combining with some element in the air to form a compound,
which was the mercuric calx.
• He called that element “oxygen,” meaning “acid maker.”
• He classified all acids to contain oxygen; (wrong
generalization).
Oxygen displaces phlogiston
• Phlogiston theory had everything upside down.
• Instead of driving off phlogiston during combustion,
burning causes a compound to combine with the gas
oxygen.
• In the case of a metal, the compound is the calx produced
(weight increases).
• In the case of wood (rich in carbon) the weight decreases
because carbon combines with something in the air and
leaves. (Carbon plus oxygen is converted to carbon dioxide).
...even modern scientific theories are just theories, not absolute fact
Oxygen vs Phlogiston
“All the facts of combustion and calcination are explained in a
much simpler and much easier way without phlogiston than
with it.
I do not expect that my ideas will be adopted at once; the
human mind inclines to one way of thinking and those who have
looked at Nature from a certain point of view during a part of
their lives adopt new ideas only with difficulty - - -.”
Lavoisier
Lavoisier announced in 1775 that he has discovered a new gas resulting upon decomposition
of Hg calx and Pb calx. He named it oxygen (meaning ‘acid maker’).
Lavoisier demonstrated (1779) its importance in respiration and glowing of candles and the
left-over part of air being toxic to animal. Thus, he established for the first time that air is
made up of two elements (one essential and another toxic for life).
Discovery of Oxygen
Carl Scheele
1742 - 1786
Swedish chemist Scheele,
identified it several years
before Priestley (1770-
1773). Unfortunately, his
scientific report sat in a
printer’s office for two
years and got published in
1777.
Priority dispute: Who discovered oxygen?
Joseph Priestley
1733 – 1804
He mentioned to
Lavoisier in 1774 about
the discovery during a
visit to Paris. Published
the results in 1775.
Antoine Lavoisier
In 1775 Lavoisier
announced to the
Academy of Science in
Paris that he had isolated
a component of air that
he called "eminently
breathable air" by
decomposition of
mercuric oxide.
1743—1794
Carl Scheele
1742 - 1786
A great chemist,
discovered 7 elements.
Slow in publishing results.
Who discovered oxygen?
Do you really need three?
Joseph Priestley
1733 – 1804
Furious free thinker and
scholar. Published every
observation. His mind was
inflexible with respect to
phlogiston.
Antoine Lavoisier
Brilliant economist,
great and meticulous
scientist. Mind was
flexible to discard old
ideas. Lacked
professional integrity.
1743—1794
On an evening in October 1774, Antoine Lavoisier, the
architect of the chemical revolution, learned that the
Unitarian English minister, Joseph Priestley, had made a
new gas. Within a week, a letter came to Lavoisier from
the Swedish apothecary, Carl Wilhelm Scheele,
instructing the French scientist how one might synthesize
this key element, the life-giver oxygen.
Scheele’s work was carried out years before but
remained unpublished until 1777. Scheele and Priestley
fit their discovery into an entirely wrong logical
framework—the phlogiston theory—that Lavoisier is
about to demolish. How does Lavoisier deal with the
Priestley and Scheele discoveries? Does he give the
discoverers their due credit? And what is discovery after
all? Does it matter if you do not fully understand what
you have found? Or if you do not let the world know?
A popular Broadway play
The Law of Conservation of Matter
By paying close attention to the weights of his experimental
ingredients, Lavoisier made the Conservation of Matter a
fundamental principle of chemistry.
The Law of Conservation of Mass
Total mass is the same
(Reactants) (Products)
Magnesium + oxygen = magnesium oxide
Explain how the experiment in
this picture demonstrates the Law
of Conservation of Mass.
Air is not an element but a mixture.
• Lavoisier was sure that air contained more than one element.
• Determined the amount of the “reacting component” in the air. He named this
reacting component oxygen.
What is an element?
Robert Boyle’s (1627-1691) definition of element
“An element is a substance that cannot be decomposed into
anything simpler”
Cavendish: “When inflammable and common air are
exploded in a proper proportion, almost all the inflammable
air, and near one-fifth of the common air, lose their
elasticity, and are condensed into dew (water).” (Done in
1781 and Published in 1784).
Water is not an element. It is a mixture.
Lavoisier (1783)
• Combustion of inflammable air with oxygen carried out in
a closed vessel yielded water in a very pure state.
• Water can be decomposed to inflammable air (hydrogen)
and oxygen. Iron filings in water rusted and released
inflammable air. Rusting occurred through the reaction of
released oxygen with iron filings.
• Thus, water can be decomposed to two elements and can
also be formed from the same two elements. Water is not
an element, it is a compound.
Water and air are not elements: Four element theory is not valid
Lavoisier: “There was no principle of scientific conduct that forbade him to
give better explanations of other men's discoveries than those they could
provide themselves, an attitude to which no man of science could take
exception.
This theory is not, as I hear it called, the theory of the French chemists. It is
mine. It is a right that I claim by the Judgment of my contemporaries and at
the bar of history.”
Cavendish’s experiments were done in 1781 and published in 1784. In the
meantime, his assistant Blagden visited Paris in 1783 and mentioned about
Cavendish’s results to Lavoisier. The latter published the water results in
1783. There was some feeling that Lavoisier might have used the information
given to him by Blagden to anticipate the publication of a discovery made by
Cavendish.
Priority disputes and Lavoisier’s reaction
Lavoisier recognized the opportunity
“The importance of the end in view prompted me to
undertake all this work, which seemed to me destined to
bring about a revolution in . . . chemistry. An immense
series of experiments remains to be made.”
Lavoisier, Lab Notebook entry dated Feb. 20, 1773
30 yrs old
Law of the conservation of Mass
Law of the indestructibility of matter
applied to chemical change
In every operation an equal quantity
of matter exists both before and after
operation.
Antoine Lavoisier
1789
Established a system of nomenclature
Conceived oxygen-based acid principle
Established the field of thermochemistry
Order in chaos
Marie had spent her teen years studying chemistry and learning to read
English. She also learned art from the revolutionary painter David. As Roald
Hoffmann traces old records, he finds Marie managing the schedule of her
husband's laboratory and creating fine detailed drawings of apparatus. She
receives no credit, ----- Was she the perfect secretary or a scientific
collaborator?
Marie-Anne Paulze
Lavoisier
Antoine Lavoisier – Sad Ending
A landmark portrait presents a
modern, scientifically minded couple
in fashionable but simple dress, their
bodies casually intertwined. Antoine
Laurent Lavoisier is often referred to
as the “father of modern chemistry”
and Marie Anne Lavoisier is known
as a key collaborator in his
experiments—aspects of the couple’s
personality that have been well
served by this famous image.
(Marie Anne Pierrette Paulze, 1758–1836)
MET, NewYork Collection
"It took them only an instant to cut off that head, and a hundred
years may not produce another like it."
Joseph-Louis Lagrange
Despite his eminence and his services to science and France, he came under attack
as a former farmer-general of taxes and was guillotined in 1794 (51 yrs old).
Priestley fled
to the U.S.
• Priestley was an enthusiastic supporter of the American and
French revolutions. His outspoken radical views enraged a mob
that burned down his house and library. Priestley escaped to the
United States where he lived for the remainder of his life.
Antoine Lavoisier, Douglas McKie, 1952
An International Historic Chemical Landmark, The
Chemical Revolution, ACS, pamphlet, 1999
Antoine Lavoisier, H. Hartley, Proc. Royal Soc. A, 189,
427-454, 1947
http://mysteryofmatter.net/Lavoisier.html
Readings
“Well, certainly, Lavoisier was one of the great, great
masters of all time.”
Humphry Davy
“Well, certainly, Lavoisier was one of the great, great
masters of all time.”
Humphry Davy
Antoine Lavoisier
1789
Humphry Davy
1778-1829
Humphry Davy: Chemistry’s First Showman
The Age of Wonder, Ch 6 & 8, R. Holmes, 2010
“I have neither riches, nor power, nor birth to recommend me.
Yet if I live, I trust I shall not be of less service to mankind and
my friends, than had I been born with these advantages”
Notebook entry at age 17
Beginning
“Fortune had smiled on Davy, perhaps too kindly in his younger
years, and left him eager for praise, jealous of rivals and anxious
to shine in every field. Those were his failings, but withal his
romantic genius made an enduring mark.”
H. Hartley,
Humphry Davy, Nelson, London, 1966
End
“There is now before us a boundless prospect of
novelty in science; a country unexplored, but noble
and fertile in aspect; a land of promise in philosophy.”
When Davy started his exploration electricity was
popularly regarded as an invisible and volatile fluid
stored in glass Leyden jars, ever ready to leap out with a
bang.
A land of promise
Born in Penzance on Dec 17, 1778
John Tonkin, Family benefactor
John B. Borlase, Local doctor
Thomas Beddoes opens ‘The
Pneumatic Institute’ in Bristol, Appoints
Davy (19 yrs old) as Laboratory Operator.
• Gas research 1798 – 1801
Royal Institution, London, 1801-
1825, Director
• Electrochemistry, Isolation of
elements, Davy Lamp invention
The Pneumatic Institute
Thomas Beddoes
Davy has actually invented a new pleasure, for which
language has no name.
Oh Tom! I am going for more this evening; it makes one
strong, and so happy!…Tom, I am sure the air in heaven
must be this wonder-working gas of delight!—
Letter to Thomas Southey, July 12, 1799
NH4NO3 → N2O+2H2O
Priestly, 1772
Nitrous oxide
N2O Session
Humphry
Davy
“We are going on gloriously. Our palsied patients are
getting better; and to be a little conceited. I am
making discoveries everyday.”
Nitrous oxide parties, early 18th century
Humphry Davy invited friends to
try laughing gas so he could
observe their responses.
"Give me more, give me more;
this is the most pleasurable thing
I've ever experienced."
Davy’s failure to capitalize on his
discovery of anesthesia doomed
thousands to needless surgical
pain.
Davy never followed up on the
idea that nitrous oxide could be
an anesthesia, his attention was
diverted by Volta’s discovery of
the battery.
Missed opportunity
“As nitrous oxide appears capable of
destroying physical pain, it may
probably be used with advantage
during surgical operations ----.”
Humphrey Davy
Moves on from nitrous oxide to carbon monoxide
Animal electricity and Battery (1791)
Luigi Galvani
1737-1798
In 1791 Luigi Galvani announced
that the contact of two different
metals with the leg muscles of a
skinned frog resulted in the leg to
twitch. Galvani interpreted that as
a new form of electricity found in
living tissue, which he called
“animal electricity.”
Lucia Galvani
Galvani believed such occurrences suggested the existence of “animal
electricity,” a phenomenon related to “artificial electricity” (produced by
an electrostatic machine or simple friction) and “natural electricity”
(associated with lightning, electric eels, etc.).
In 1786 Luigi Galvani hung the legs of a
dead frog on a railing in a
thunderstorm to see if lightning would
make them twitch….
Frogs and Animal Electricity
Frogs and Animal Electricity
However, one day
Galvani made the
legs twitch without
any charge.
Galvani believed he had created
“Animal Electricity” – and many
people began to believe that this was the
secret of life itself. By creating a static
charge, he and other scientists could get
the dead frog’s legs to twitch… later on
dead people too!
Volta believed the brass hooks on which the legs
hung were reacting chemically with an iron stand
to create an electric current.
Volta made the first battery in 1800.
Alessandro Volta’s Response (ca.1800)
Alessandro Volta
1745-1827
Alessandro Volta realized that most of the
unusual electrical behavior observed by Galvani
involved two different types of metals, such as the
iron of a scalpel and the brass of a hook. This led
him to suggest that the animal tissue was not
necessary; any moist material between different
metals would produce electricity. Instead of
“animal electricity,” Volta believed in “metallic
electricity.”
Three Parts of an Electric Circuits
1. Source of electrical energy
2. Closed path
3. Device to use electrical energy
The voltaic pile, invented by Alessandro
Volta in 1800, was the first device to
provide a steady supply of electricity.
Volta’s pile (1800)
Volta’s pile (1800)
Cu Zn “couple”
1.1 v
301v
26 v
110 v
165 v
In 1800, Alessandro Volta (1745 –
1827, an Italian physicist) discovered
that chemical reactions could be used
to create positively charged anodes
and negatively charged cathodes.
In 1800 A. Volta invented
the voltaic pile, which was
one of the first electric
batteries. It was essentially
a stack of alternating metal
discs separated by brinesoaked
material that helped
make them more
conductive.
Volta demonstrated his
battery for the French
leader Napolean and
promptly earned a nice
gold medal, -----
Volta’s pile, the first battery
“…though there was a high
intensity of action, the water of the
solutions alone was affected, and
hydrogen and oxygen disengaged
with the production of much heat
and violent effervescence.”
(electrolysis of water)
Humphry Davy built his own Voltaic
pile and experimented
Birth of electrochemistry
Li Be B
Na Mg Al
K Ca Ga
Rb Sr In
Cs Ba Te
Davy’s excitement on elemental discoveries
“. . . when he saw the minute globules of
potassium burst through the crust of
potash, and take fire as they entered the
atmosphere, he could not contain his joy–
he actually bounded about the room in
ecstatic delight; and . . . some little time
was required for him to compose himself
sufficiently to continue the experiment”
Edmund Davy, Cousin who watched the expt.
1807
Na
Davy used electricity to split up compounds to form elements
Davy’s view of a chemical bond:
The ions make a bond
Using this set-up, Davy showed that a precipitate of BaSO4 was formed in
the middle compartment, thus proving that barium ions migrated towards
the negative electrode and sulphate ions towards the positive one.
Davy’s view of chemical bonding
Opposite charges attract
1807-8
Humphry Davy
Big Science
at London’s
Royal Institution ~650 v
Battery of Berzelius
Napoleon’s Response
(via Gay-Lussac)
600 ´ 1 kg Cu plates
600 ´ 3 kg Zn plates
2.6 tons of metal
• The first preparation of nitrous oxide in a pure form; Davy was also
the first to recognize its anesthetic properties.
• The isolation of metallic potassium, sodium, barium, strontium,
calcium, magnesium, and boron.
• Davy was the first to argue that if electricity could be generated by
chemical action then, conversely, electricity could decompose
compounds into their fundamental elements (birth of electrochemistry)
• The realization that chemical forces were, fundamentally, electrical in
nature (birth of the Nature of a chemical bond)
Davy Makes Science Fashionable
Forgotten Davy lamp
• Enormous coal mine explosions in England during 1800s.
• Each miner carried a wax candle stub on his helmet or in his hand.
• The open flame ignited the gases (methane) killing a large number of miners
every year.
• The miners approach Davy at the Royal Institute
SIR,
I had the honour of receiving the letter which you addressed to me in
London at this place, and I am much obliged to you for calling my
attention to so important a subject.
It will give me great satisfaction if my chemical knowledge can be of
any use in an inquiry so interesting to humanity, and I beg you will
assure the Committee of my readiness to co-operate with them in any
experiments or investigations on the subject.
I shall be here ten days longer, and on my return south will visit any
place you will be kind enough to point out to me where I may be able to
acquire information on the subject of the coal-gas.
Your obedient, humble servant,
H. DAVY.
Davy’s life holds some lessons for ethics and science today
August 3rd, 1815.
Chief Mining Engineer John Buddle
Approaches Davy at the behest of
miners
‘After a great deal of conversation with
Sir Humphry Davy, and he making
himself perfectly acquainted with the
nature of our mines and what was
wanted,------ he said “ Do not despair, I
think I can do something for you in a
very short time”.’
John Buddle
1773-1843
• Studied the problem for three weeks in Durham,
visiting mines and talking to miners;
• Went back to the lab for three months.
• Built a working prototype lamp what would be
known as the Davy Lamp.
• Returned to the mines. He spent hours underground,
teaching safety techniques, refining the design.
Invention of Davy lamp
Invention of miner’s lamp, Davy Lamp
Training miners with Davy Lamp
John Buddle: “We have at last subdued this monster”.
In September 1816 ‘we, the undersigned miners at the
Whitehaven Collieries' thanked Davy for his 'invaluable
discovery of the safe lamps, which are to us life preservers'.
Davy lamp is still popular world over
Davy's high-minded claims produced a bitter priority dispute. In the
spring of 1816 the engineer at the Killingworth mine, just north of
Newcastle, George Stephenson, challenged Davy's precedence, and
accused him of plagiarising of his own 'Geordie Lamp'.
Priority Dispute: Davy lamp
Buddle urged Davy to take out a patent, pointing out that he could not only
make his fortune but control the quality of the lamps issued to miners.
Davy consistently refused, although he knew his colleague Wollaston had
made a fortune with a patent on processing platinum. Yet Davy was hugely
proud of his achievement and was never modest about it.
Priority dispute on the discovery of iodine with the gifted young chemist Joseph GayLussac.
Gay-Lu sac, Davy's exact contemporary.
Gay-Lussac's short paper was actually presented and published first, on 12
December. Davy, taken by surprise, presented his to the Academie on 13
December, but antedated it to 11 December, and had it published as such in the
Journal de Physique. He claimed, perhaps justly, that he had previously shared
his key ideas with Gay-Lussac.
Davy's surprising sharpness in a 'priority' controversy was noticed by Faraday.
Priority Dispute: Iodine
Two not-so-well-known chemists, N. Clément and C. B. Desormes had reported that a
strange new substance had been discovered in seaweed. Gay-Lussac was assigned to
review their experiments and repeat them to make sure the results were correct. Six
days before the announcement of the results by Gay-Lussac, Ampère, Clément, and
Desormes paid a visit to Davy and showed him the sample. Davy immediately isolated
and identified the element as iodine.
ChemMatters, December 2006, p. 18
Outstanding
Lecturer &
Performer
The first one-way
street in the world
The Age of Wonder: Communication with the public
“I was made to write out the first lecture entirely, and Davy took me
into the lecture hall the evening before I was to talk and made me
read it all out while Davy sat in the furthest corner and listened; and
then Davy read the lecture while I listened. Next day I read it to an
audience of about 150 to 200 people and they gave me a very
generous plaudit at the conclusion.”
John Dalton on his first lecture at Royal Institution in 1803
Davy’s advice on giving on lectures
Davy trusted the experiments more
than his brain
“One good experiment is worth more than the
ingenuity of a brain like Newton's."
Recipe for Research
“Observation, Experiment and Analogy”
• Observe to formulate a problem
• Experiment to gain an understanding
• Compare the results with known to generate a hypothesis
Readings
http://mysteryofmatter.net/Davy.html
The Age of Wonder, R. Holmes, 2008, Ch 6 and 8
https://www.rigb.org/whats-on
Sir Humphry Davy: Boundless Chemist, Physicist, Poet and Man of Action,
JM. Thomas, PP. Edwards, and VL. Kuznetsov, ChemPhysChem, 2008, 9, 59
Sir Humphry Davy: natural philosopher, inventor, discoverer, poet, man of action.
JM. Thomas, Proc. Am. Phil. Soc. 2013, 157, 143.
Sir Humphry Davy and the coal miners of the world: a commentary on Davy (1816)
‘An account of an invention for giving light in explosive mixtures of fire-damp in
coal mines’, JM Thomas, Phil. Trans. R. Soc. A 2014, 373: 20140288.
Humphry Davy
1778-1829
Humphry Davy: Chemistry’s First Showman
• Nitrous oxide
• Elements Na, K, Cl, Br, I, etc.
• Basis of electrochemistry
• Davy lamp
• Lead the Royal Society
• Connected science to society
• Encouraged and mentored Faraday
The Greatest Discovery of Davy: Michael Faraday
The Electric Life of Michael Faraday, A. Hirshfield, 2006
Faraday, Maxwell, and the Electromagnetic Field: How Two Men Revolutionized Physics,
N. Forbes and B. Mahon, 2014.
Faraday Rediscovered, D. Gooding and F. A. J. L. James, 1985
Michael Faraday, L. Pearce Williams, 1964
• Born near London on Sep 22 1791, three siblings
• Father a blacksmith, mostly unemployed and unhealthy
• Mother from a family of farmers
• Deeply religious, Sandemanian sect of Christianity
• Educated in rudimentary reading, writing and arithmetic,
age 5-13
The Beginning
• To support the family took up a job at age 13 as an
errand-boy for a local shopkeeper
• At the age of 18 he became an assistant to a book binder
• While he was a book binder a French roommate taught
him to draw three dimensional drawings and French
• Took courses on elocution
• As a book binder he came across two important books
The Beginning
•The Encyclopedia Britannica – his source for electrical knowledge and much more
•Conversations on Chemistry – 600 pages of chemistry for ordinary people written by
Jane Marcet based on Davy’s lectures at the Royal Institution
Faraday, a bookbinder's apprentice at the time,
attended around 13 lectures by silversmith John
Tatum (1772-1858) between February 1810 and
September 1811. The notes Faraday made from
these lectures formed four volumes and 300 pages
and helped him start his career in science.
John Tatum’s lectures (1772-1858)
exposed Faraday to science
Tatum founded the City Philosophical Society in 1808 where Faraday and other
scientists received inspiration.
Building Confidence
“When I questioned Mrs. Marcetʼs book (Conversations on
Chemistry) by such little experiments as I could perform, and
found it true----, I felt I got hold of an anchor of chemical
knowledge---.”
Michael Faraday
Jane Marcet, 1769-1858
The book that recorded
Davy’s lectures at RI
“My desire to escape from trade, which I thought vicious and
selfish, and to enter into the service of Science, which I imagined
made its pursuers amiable and liberal, induced me at last to take
the bold and simple step of writing to Sir H. Davy, expressing my
wishes, and a hope that if an opportunity came in his way he
would favor my views; at the same time, I sent the notes I had
taken of his lectures.” (1812)
Based on the letter Faraday wrote about the experience later in life after
Davy’s death to J.A. Paris. (1829)
Getting Started
“Sir,– I am far from displeased with the proof you have given
me of your confidence, and which displays great zeal, power
of memory, and attention. I am obliged to go out of town and
shall not be settled in town till the end of January; I will then
see you at any time you wish. It would gratify me to be of any
service to you; I wish it may be in my power.
I am, Sir, your obedient humble servant,
H. Davy.”
Davy’s encouraging reply to Faraday
Faraday was grateful to Davy till the end of his life
A revealing letter where Davy cautions
“At the same time that he thus gratified my desires as to
scientific employment, he still advised me not to give up
the prospects I had before me, telling me that Science
was a harsh mistress, and in a pecuniary point of view
but poorly rewarding those who devoted themselves to
her service. He smiled at my notion of the superior
moral feelings of philosophic men and said he would
leave me to the experience of a few years to set me right
on that matter.”
A letter written to a friend by Faraday in 1829
Getting the foot in the hole, Apprentice as a chemist
Lady Davy in front of guests ordered Faraday to take his meal in
the kitchen with the servants.
Faraday’s tough time with Lady Jane Davy
“Alas!, how foolish perhaps was I to leave home, to leave those
whom I loved and who loved me ----. And what are the boasted
advantage to be gained? Knowledge. ---- What a result is obtained
from knowledge and how much must the virtuous human mind be
humiliated --- Ah Ben, I am not sure that I have acted wisely in
leaving a pure and certain enjoyment for such a pursuit.”
Faraday to his hometown friend,
Hans Christian Ørsted, 1777-1851
First to establish a connection
between electricity and magnetism
André-Marie Ampère
1775-1836
Early observations on the
connection between
magnetism and electricity
An unexpected turn in the life of MF
https://www.youtube.com/watch?v=qS361iadCPA
William Hyde Wollaston
1766 –1828
Davy was trying to re-create a famous electromagnetism experiment of
Ørsted with fellow chemist William Wollaston, wondering why applying an
electric current to a wire caused that wire to behave like a magnet. He
could not make the experiment work.
He teasingly told Faraday to try his hand at it after he was done cleaning the
lab. Faraday figured it out, and the result was the first induction motor,
which converts electrical current into continuous mechanical motion.
Humphry Davy
1778-1829
World’s First Electric Motor-1821
Electromagnetic rotation experiment of Faraday
Wire fixed
Magnet free
Magnet fixed
Wire free
https://www.youtube.com/watch?v=EECRoYNaSxg
World’s First Electric Motor-1821
Electromagnetic rotation experiment of Faraday
Wire fixed
Magnet free
Magnet fixed
Wire free
Gift model
Exploratory Experiments, Ampere, Faraday and the Origins of Electrodynamics, F. Steinle & A.Levine, 2005
Magnetic Effects from Electricity
The publication that created excitement and problems
On Some New Electromagnetic Motions and the Theory
of Electromagnetism M. Faraday, Quarterly Journal of
Science, 1821-23 (three articles)
Faraday published without acknowledging Davy and
Wollaston.
Davy and Wollaston accused Faraday of plagiarizing their idea.
Public liked the little and pocket-sized motor that were gifted and sold.
But, Faraday was out of favor with the old guards of British scientific establishments.
They were unsure of his knowledge to make such an important discovery.
Public and old guards were not aware that Faraday is the author of an authoritative
review on electromagnetism published in Annals of Philosophy under a pseudo-
name.
(US$ 4,060.35)
Science is a human endeavor, driven by hopes, dreams and
aspirations. They may be brilliant, even geniuses. But as human
beings they may also be seriously flawed.
Mentor and mentee relationship was complex
Michael Faraday
1791-1867
Sir Humphry Davy
1778-1829
Occasionally, science can take on personal, almost vindictive
quality.
"I am compelled to say I have not found that kindness,
candor and liberality at home which I have now on several
occasions uniformly experienced from the Parisian men of
Science ... Considering the very subordinate position I hold
here and the little encouragement which circumstances hold
out to me I have been more than once tempted to resign
scientific pursuits altogether ... I struggle on in hopes of
getting results at one time or another that shall by their
novelty or interest raise me into a more liberal and active
sphere."
To Ampere, Faraday privately complained
Faraday finds a trusted friend in Ampere
---- believe me there is no one more interested in your success
& welfare than your sincere well wisher & friend, H. Davy."
Complex relationship between Davy and Faraday
Davy to Faraday, "I think you are a better chemist than Donovan."
Compliments
Faraday's nomination to the Royal Society was announced at ten
successive Royal Society meetings and, at the eleventh, on
January 8, 1824, secret ballots were cast. Faraday was electedwith
one dissenting vote by Davy.
Davy tried to block his own protege from "rising to the light.”
Complex relationship
Recommended Faraday to be the Director of RI and
assigned him on an uninteresting project on glass (1825-
1831).
Humphry Davy dies in 1829.
First Electromagnetic Induction
Electricity to Magnetism
Series of pioneering discoveries 1831Magnetism
to Electricity
Transformer
Twitches only when the switch goes on-off
• Faraday presented the discovery to Royal Society on November 24, 1831
• Faraday informed French physicist J. N. P. Hachette
• J. N. P. Hachette passed on the information to Francois Arago
• Arago presented the work to Academy of Sciences on December 26, 1831
• Two Italian scientists came to know of this and published as their own on
January 1832, with the date of November 1831.
• Faraday did not publish the work till early 1832
• Finally sorted out, French and Italian workers agreed that the original
discovery was due to Faraday and apologized
• Faraday learnt the lesson: ‘never publicize till you publish’
Never publicize till you publish
Induced currents)
• When a current is turned on or off in coil A, a magnetic field is produced which
also passes through coil B.
• A current then briefly appears in coil B
• The current in coil B is called an induced current.
• The current in B is only present when the current in A is turned on or off, that
is, when the current in A is changing
A
magnetic
field lines
current
indicator
switch
battery
B
A magnet moved in or out of a helical coil of
wire produces an electric current in the coil.
The transformer
The voltage on the secondary depends on the number
of turns on the primary and secondary.
Step-up à the secondary has more turns than the primary
Step-down à the secondary has less turns than the primary
Induced currents
a) No current is induced if the magnet is stationary.
b) When the magnet is pushed toward the coil or pulled away
from it an induced current appears in the coil.
c) The induced current only appears when the magnet is being
moved
(a) (b) (c)
Electric Generators
When a coil is rotated in a magnetic field, an induced current
appears in it. This is how electricity is generated. Some external
source of energy is needed to rotate the turbine which turns the coil.
Faraday’s breakthroughs propelled our
society to a new level of knowledge
• We use motor in thousands of applications: disk drive, video
machine, fan, pump, washing machine, refrigerator, air
conditioner, aeroplane …
• We need generator to produce electricity
• We need transformer for long-range electricity delivery and in
some devices
• Faraday’s inventions compose the frame of our electric world
When Faraday was nearly fifty-four years old, attempted, for the sixth
time, to discover a connection between light and electricity. He repeated
the experiments to vary the polarization of a beam of light by passing it
through an electrolyte transmitting a current. Then he tried passing the
beam through powerful electrostatic tension by electrical machines but
was unable to observe any effect.
After a fortnight, he tried the effect of powerful magnetic fields. He
laid a piece of heavy glass across the poles of the electro-magnet and
passed a beam of polarized light through it longitudinally. He found that
the polarization of the beam had been affected; "thus magnetic force
and light were proved to have relations to each other."
Effect of Electricity and Magnetism on Light
Faraday Effect: Magnetic field
rotates plane polarized light
Light is an electromagnetic wave
In 1845, Michael Faraday discovered
that the plane of polarization of linearly
polarized light is rotated when the light
rays travel along the magnetic field
direction in the presence of a
transparent dielectric, an effect now
known as Faraday rotation
Michael Faraday
1791-1867
“I happen to have discovered a direct relation
between magnetism and light, also electricity and
light---and the field it opens is so large & I think rich
that I naturally wish to look at it first”
To Ampere, Nov 1845
What is light?
A link between magnetism, electricity and
light established
Michael Faraday
1791-1867
Nanoscience
150 years old gold nanoparticles of Faraday
on display at RI
Faraday’s gold colloidal solution
on display at RI, 1856
Stained glass vessels
of ancient times, BC
Faraday-Tyndall effect
Faraday realized that this cone effect was
made because the fluid contained
suspended gold particles that were too
small to see with the scientific apparatus
of the time but which scattered the light to
the side (Faraday-Tyndall effect).
Beginnings of Nanoscience
Faraday-Tyndall effect
Faraday is the father of modern nanoscience and nanotechnology.
Gold chloride + Phosphorous = Gold nanoparticle
“No dissolved gold, only diffused gold”
1866, Mrs. Faraday: “Don’t you
remember those beautiful gold
experiments that you made?”
Faraday: “Oh yes, beautiful gold,
beautiful gold”
8-25-1867, Faraday died while sitting
in his chair at the age of 75
Faraday’s age, health and laboratory
safety issues caught up with him
“Tyndal, I must remain plain Michael Faraday to the last”
Discoveries with no mathematical equations
Electromagnetic induction ------Electrical engineering
Transformer and dynamo ------ Industrial revolution
Theory of electricity and magnetism: not liquids but fields
Magneto-optical effect or Faraday effect;
Provided a common thread between electricity, magnetism and light
Electromagnetic theory of light
Interaction between electrical & magnetic forces and molecules
Dielectrics, para-magnetism and dia-magnetism
Theory of electrolysis Electrochemistry
Discovery of benzene Dye industry
Gold nanoparticles Nanoscience
https://www.youtube.com/watch?v=Wyh7E_FzxgY
"Brothers in intellect, Davy and Faraday, however,
could never have become brothers in feeling; their
characters were too unlike. Davy loved the pomp
and circumstance of fame; Faraday the inner
consciousness that he had fairly won renown. They
were both proud men. But with Davy pride
projected itself into the outer world; while with
Faraday it became a steadying and dignifying
inward force."
John Tyndall
1820-1893
"A father is not always wise enough to see that his
son has ceased to be a boy, and estrangement on
this account is not rare; nor was Davy wise enough
to discern that Faraday had passed the mere
assistant stage and become a discoverer."
Similar yet dissimilar
Davy’s pure scientific method:
Observation, Experiment, Analogy
Secret of Faraday’s success as a scientific investigator
Work, Finish, Publish.
If I could live my life over again I would study
mathematics; it is a great mistake not to do so, but it is
too late now (Faraday 1857)
Listen to the pioneers
European and Asian philosophers
Alchemists
Phlogistonists
Modern chemists
The Aristotelian tradition and medieval alchemy
eventually gave rise to modern chemistry