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."