Slide 1

Report
System of Measurement
Origin of the Metric System
• Gabriel Mouton, the vicar of St. Paul's Church in
Lyons, France, is the “founding father” of the
metric system
• He proposed a decimal system of measurement
in 1670.
• Mouton based it on the length of one minute of
arc of a great circle of the Earth (now called a
nautical mile, 1852 meters).
• He also proposed the swing-length of a
pendulum with a frequency of one beat per
second as the unit of length (about 25 cm)
The Metric System
• The political sponsor of weights and measures
reform in the French Revolutionary National
Assembly was the Bishop of Autun, better
known as Talleyrand
• The French Academy appointed several
committees to carry out the work of developing
a usable system of weights and measures for
France- Lavoisier was a member
The Metric System
• One of the committees recommended a
decimalized measurement system based
upon a length equal to one ten-millionth of
the length of a quadrant of the earth's
meridian (i.e., one ten-millionth of the
distance between the equator and the
North Pole).
The Metric System
• In 1790, in the midst of the French Revolution, the National
Assembly of France requested the French Academy of Sciences to
“deduce an invariable standard for all the measures and all the
weights.”
• The Commission appointed by the Academy created a system that
was, at once, simple and scientific.
• The unit of length was to be a portion of the Earth's circumference.
Measures for capacity (volume) and mass were to be derived from
the unit of length, thus relating the basic units of the system to each
other and to nature.
• Furthermore, larger and smaller multiples of each unit were to be
created by multiplying or dividing the basic units by 10 and its
powers.
• This feature provided a great convenience to users of the system, by
eliminating the need for such calculations as dividing by 16 (to
convert ounces to pounds) or by 12 (to convert inches to feet).
National Prototype Meter No. 27
ca. 1875-1889 NIST Museum Collection
The Metric System
• The initial metric unit of mass, the “gram,”
was defined as the mass of one cubic
centimeter — a cube that is 0.01 meter on
each side — of water at its temperature of
maximum density. For capacity, the “litre”
(spelled “liter” in the U.S.) was defined as
the volume of a cubic decimeter — a cube
0.1 meter on each side.
The Metric System
• The standardized structure and decimal features
of the metric system made it well suited for
scientific and engineering work. Consequently, it
is not surprising that the rapid spread of the
system coincided with an age of rapid
technological development. In the United States,
by Act of Congress in 1866, it became “lawful
throughout the United States of America to
employ the weights and measures of the metric
system in all contracts, dealings or court
proceedings.”
Lavoisier
From Mineralogy to Geology
• Lavoisier's interest in geology is reflected
in the Atlas minéralogique de la France,
Guettard's vast undertaking which had
both theoretical and practical ends.
• It was to provide the duc d 'Orléans with
maps showing all natural resources in the
kingdom: "quarries, excavating mines,
mineral springs, and all raw materials
contained in the earth."
From Mineralogy to Geology
• Starting from the works of his masters - Buffon
(1707-1788), Guettard and Guillaume François
Rouelle (1703-1770) -, he felt ready to construct
a theory of the earth's formation.
• "There will result from this immense
undertaking," he announced, "exact knowledge
concerning the former boundries of the sea, the
bed it occupied, and the former arrangement of
the continents; in a word, a system based
entirely on experiments and sound observations
of the changes that have taken place on the
earth."
From Mineralogy to Geology
• The earth's crust, according to him, was
formed from an old soil, composed of
mountainous masses of granites poor in
fossils, and a more recent one,
fossiliferous and sedimentary. The rocks of
the original soil, he wrote, "are arranged in
perpendicular layers or inclined towards
the horizon... They are composed of
quartz, granite, shale, slate and talcose."
Meteorology
• Meteorology was his second specialty. When he was twenty, he
had begun making barometric observations, and he continued
this activity all his life.
• In 1776, he carried out a comparative study of the lowest
temperature observed during that winter (-14°) with that of the
winter of 1709 (-15° 1/2); the data collected by the thermometer
devised by Réamur in 1732 were not in agreement with those
obtained with more recent inventions:
• It was the occasion for him to define precise rules for the
fabrication and graduation of thermometers and to deposit
twelve standard models at the Academy of Sciences.
• In 1781, studying natural electricity and the formation of
thunder, he demonstrated with Laplace and Volta that
hydrogen, nitric oxide, carbon dioxide and water vapor, in
passing from the liquid to the vapor state emitted electrical
charges measurable by the electrometer.
• With Benjamin Franklin (1706-1790), he installed lightening
rods on the roof of Saint-Paul's Church.
Meteorology
• He considered weather forecasting to be almost as
difficult an art as medicine: one needed daily
measurements of atmospheric pressure, the velocity and
direction of winds at different altitudes and the
hygrometric state of the air.
• He created a network of correspondents in France and
Europe and selected barometers and wind gauges.
"With all this information," he wrote, "it is almost always
possible to predict one or two days in advance, within a
rather broad range of probability, what the weather is
going to be; it is even thought that it will not be
impossible to publish daily forecasts which would be very
useful to society."
Antoine-Laurent Lavoisier
The Father of Modern Chemistry
Chemical Revolution. Over the 20 year period 1770 - 1790, the science of chemistry
experienced a revolution so fundamental and so complete that there has been nothing
like it since. The architect of the revolution was one man — Antoine Lavoisier.
Antoine-Laurent Lavoisier (1743–
1794)
• Succeeded in producing more and better
gunpowder by increasing the supply and
ensuring the purity of the constituents—
saltpeter (potassium nitrate), sulfur, and
charcoal—as well as by improving the
methods of granulating the powder.
• Traité Élémentaire de chimie, and began a
journal, Annales de Chimie, which carried
research reports about the new chemistry
Lavoisier
• Lavoisier's chemistry was his systematic
determination of the weights of reagents
and products involved in chemical
reactions, including the gaseous
components, and his underlying belief that
matter—identified by weight—would be
conserved through any reaction
Lavoisier
• Among his contributions to chemistry
associated with this method were the
understanding of combustion and
respiration as caused by chemical
reactions with the part of the air he called
"oxygen," and his definitive proof by
composition and decomposition that water
is made up of oxygen and hydrogen
Lavoisier believed that weight was
conserved through the course of chemical
reactions — even those involving gases.
• He proved the Law of Conservation of Mass, showing
that the mass of the reactants had to equal the mass of
the products.
• Regarding respiration, he showed that oxygen is
consumed and carbon dioxide is given off.
• In 1783 he began heat measuring experiments using a
calorimeter and showed that the heat produced by
respiration was equal to the heat produced when the
same amount of oxygen was used to burn charcoal.
• He also used a calorimeter to find the specific heats of
various substances and measure the heat produced in
chemical reactions.
Chemical Reactions
• Carbon Dioxide (CO2) : Fixed Air
• Carbon Dioxide was the first gas prepared and
truly characterized as a pure substance.
• It was studied around 1750 by Joseph Black
who named it "fixed air." Information about "fixed
air" was received through the equation:
• limestone + acid --> a salt + fixed air (modern
equation: CaCO3 + 2HCL --> CaCl2 +H2O +
CO2)
• While Black did not find any commercial use for
it, Joseph Priestly prepared carbonated
beverages as early as 1772 in London
Antoine-Laurent Lavoisier conducts an experiment on
human respiration in this drawing made by his wife, who
depicted herself at the table on the far right
A replica of Lavoisier's laboratory at the
Deutsches Museum in Munich, Germany. The
large lens in the center of the picture was used to
focus sunlight in order to ignite samples during
combustion studies
Oxygen and the end of
Phlogiston
• The doctrine of Phlogiston explained that
phlogiston was released upon calx
formation.
• While modern scientists recognize the
implication that this: phlogiston must have
a negative weight, early phlogistonists
(Becker, Stahl) were not bothered as they
considered phlogiston to be something of
a philosophical concept.
Oxygen and the end of
Phlogiston
• Later phlogistonists such as Priestley did
consider phlogiston to be a material
substance (Cavendish believed it to be his
inflammable air, now H2)
• But because the theory explained so many
chemical phenomena, they were able to
overlook its shortcomings.
• But not Lavoisier!
Oxygen and the end of
Phlogiston
• Lavoisier heated tin in air in a closed
vessel.
• The tin increased in mass upon forming
the calx [now SnO] and air rushed into the
vessel as it was opened.
Oxygen and the end of
Phlogiston
• In 1777, Lavoisier conducted an
experiment that established a fatal
shortcoming of the phlogiston theory.
• He heated mercury and air using a bell-jar
for 12 days.
• Red mercury calx (now HgO) formed and
the volume of air decreased from 50 to 42
in3.
Oxygen and the end of
Phlogiston
• The remaining air was determined to be
atmospheric mofette, and later renamed
azote (now nitrogen).
• The red [HgO] was heated in a retort
producing 8 in3 of dephlogisticated air
[O2].
Oxygen and the end of
Phlogiston
• The sequence of experiments established
that heat caused formation of a calx (the
doctrine of phlogiston explained phlogiston
was released):
– Hg(l) + O2(g)
HgO(s)
• And then stronger heating reverted the
calx back to the original substances (which
the doctrine of phlogiston would predict to
be impossible):
– HgO(s)
Hg(l) + O2(g)
Water
• Proof of the validity of Lavoisier's Oxygen
Theory came when Lavoisier
– (a) decomposed water into two gases, which
he named hydrogen and oxygen, and then
– (b) reformed them into water as had been
previously done by Priestley (1781) and then
quantitatively by Cavendish.
Production of hydrogen
Lavoisier and Du Pont de Nemours
Condemned to the Guillotine
• On May 8, 1794, the Revolutionary Tribunal tried thirtytwo Farmers General on charges of misappropriation of
funds, excessive profits, abusive distribution of bonuses,
unjustified delay in payments to the Public Treasury and,
especially, for increasing its profits by introducing
excessive amounts of water into tobacco, and of having
used these profits in a "plot against the French people
tending to favor by all possible means the success of the
enemies of France."
• Joseph Louis Lagrange (1736-1813) commented: "It
took them only an instant to cut off that head, but it is
unlikely that a hundred years will suffice to reproduce a
similar one."

similar documents