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SC/NATS 1760 – Lecture 13 – Science and Industry in the 18th and 19th Centuries - Economic factors do not determine “what is found out”, but “when and how” new facts are introduced Steam Engine and Thermodynamic Theory - Thermodynamic theory and steam engines - Vacuum and atmospheric pressure - Christian Huygens & Denis Papin (1673) small charge of gunpowder exploded in cylinder, vacuum causes cylinder to be pushed downwards by air pressure, lifting 1600lbs through 5 feet - Steam engine: piston covers chamber, steam pushes it up, cooling the steam causes it to condense, creating vacuum, and weight of atmosphere presses down - Thomas Newcomen: steam engine in 1712 - Newcomen engine inefficient, demonstrated that a vacuum could be harnessed - James Watt introduced a separate condenser for steam, improved efficiency - No significant scientific contributions to the early development of steam engine Thermodynamic Theory - Joseph Black: specific heat and latent heat o Specific heat: different substances are heated to different degrees by the same amount of heat o Latent heat: when you heat a material and it changes phase the temperature does not increase for a time, as the energy is used to change it from one phase to another, this energy is latent in the material - Heat is a substance found inside of things, imponderable, like light or electricity - Sadi Carnot: first person to quantify heat transformation into work - Conservation of energy, heat, motion and electricity are different forms of energy Electricity - Electricity an imponderable fluid, passed through certain substances, and not others, stored in objects called Leyden jars - Storage of electricity and experiments - Benjamin Franklin: electricity has a charge, lightning and electricity the same - Coulomb measured electricity with a magnetic needle, electricity and magnetism and inverse square laws - Patterns: energy was convertible, different forces (gravity, electricity, magnetism) behaved according to inverse square laws - Alessandro Volta –a damp cloth between two pieces of metal could produce electricity, first battery - Electricity used for different purposes: medical, decomposition of materials - Oerstead - connection between electricity and magnetism - Michael Faraday: moving electrical current produces a magnetic field, and vice versa - Currents can be produced by moving magnets, basis of electric motor Chemistry - Chemical processes: o Rusting of metal o Calcination: add heat to metal and get ashen calx o Calx can be transformed back to the original metal by heating it with charcoal o Mixing solutions can change their color o Distillation for purification Combustion, Experiments with Fire - Progress and the problem of combustion - Combustion is a primary process in chemistry and alchemy - Aristotle’s 4 element theory - Fire as a weightless fluid with small particles that penetrate other substances - 1703 Ernst Stahl borrowed from alchemical theory to explain combustion - Alchemical theory something escaped during combustion - He called the substance released phlogiston (Greek phlogistos, meaning burnt) - Phlogiston and combustion (fire, heat, light) - Combustion a loss of phlogiston, leaving ash behind - Air supports combustion, absorbing phlogiston, to saturation - Phlogisticated air is saturated and will not support combustion - Dephlogisticated air will support combustion - No combustion in a vacuum, as it cannot absorb phlogiston - Weight gain on combustion, phlogiston has negative weight, or levity Pneumatics, Experiments with Air - Vacuums used to develop scientific theories, liquids evaporate in a vacuum, water boils at lower temperature - Experimental isolation of different kinds of air - Henry Cavendish: immersed metals in acid to produce gas, inflammable air, or phlogiston o Mixing two kinds of air together (common and inflammable) with a spark produced a liquid o Dephlogisticated air also produced liquid when sparked - Joseph Priestly: heating the calx of mercury produces respirable air, or dephlogisticated air Lavoisier and the Revolution in Chemistry - Antoine Laurent Lavoisier, beheaded during Terror of French Revolution - 1789, Elements of Chemistry, a fundamental change in chemistry - Lavoisier’s work standardized quantitative laboratory methods in chemistry - He applied “methods of physics”, i.e. Newton, to chemistry - “Balance approach”, weight of products and reactants to be equal Lavoisier and Combustion: - Certain metals (mercury and lead), gained weight when heated - Objects heated in air would combust Lavoisier reversed phlogiston theory; air was absorbed during combustion, rather than phlogiston being emitted When you burn a metal it absorbs oxygen and becomes a metallic oxide Calx’s are thus metal + oxygen “Eminently respirable air” or flammable air, was found in acids, named it “oxygen”, or “acid begetter” in Greek Water is a complex substance made up of two kinds of air or gasses Nomenclature - Substances named according to known components, using Greek and Latin names - Standardization in textbooks - Element: whatever was left over after analysis, an experimental definition Science and Capitalism - “… science was affecting the development of capitalism, enabling it to turn away from the individualist free competition of small-scale industry to the large monopolist undertakings with deliberately planned and scientific production methods.” p 658 - Science and understanding of world, science and changing or manipulating world - Scientists and tradesmen, and the availability of capital allow shift