Lecture 2 - Weights & Analysis

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Department
History and Philosophy of Science and Technology
Course
HPS211H1
Professor
Chen- Pang Yeang
Semester
Summer

Description
HPS211 Lecture 2 MAY17/2012 Weight - Major topic of research during the Chemical Revolution was weight I. Origin of chemistry & alchemy - People interested in the properties of matter - Transformation of matter (i.e. salts/crystals dissolving in acidic water) - Aristotle has a theory for the cause of the transformation of matter  4 elements: Air (wet, hot), Fire (hot, dry), Earth (dry, cold), and water (cold, wet)  Combination of elements indicates a substances’ properties - Alchemy: interested in transformation of matter for not only intellectual reason but also practical reasons  The acts/skills of transforming base metals into gold (precious metal) (i.e. copper into gold)  Alchemists witnessed a lot of matter transformation (i.e. liquid to solid, etc.) Therefore, assumed the possibility of transforming base metals into gold  Alchemical 3 Principles: Mercury, Sulphur, and Salt  Employed for understanding chemical phenomena  Not necessarily in contradiction with Aristotelian elements  Abstract elements – cannot be found in our daily lives  3 principles responsible for the chemical properties of substances  Alchemy far from primitive; associated with magic, charlatan, witchcraft, etc.  Alchemy was very secretive because of its potential gain in revenue and for negative views (i.e. cheating)  Texts about alchemy were written in esoteric texts and practices  In religious (catholic) places, alchemy was called a religious heresy for its seeming association with witchcraft  Also, a threat to monetary order since there’s a possibility of transforming metal into gold.  Alchemy is a secret, private form of inquiry to nature II. Newtonian Chemistry & Phlogiston chemistry - Two alchemists/Scientific Revolutionaries: Robert Boyle and Isaac Newton  Boyle was the founder of Chemistry  Newton was a mathematician and physicist and later became interested in alchemy  They were both interested in WHY matter transform  Reformed alchemy including its means of practice  Reformed from a secretive alchemy to a more open, public kind  Alchemy  “Chymistry”  Chemistry - Copuscular Theory of Chemistry  BOYLE: Properties and transformation of matter determined by motions and configurations of constituent corpuscles  different between iron and gold – atomic configuration. Therefore, if iron`s atomic configuration can be rearranged, it can be turned into gold  NEWTON: Properties and transformation of mattth determined by forces between corpuscles  Newtonian chemistry prevailed in 18 c. in England and France  Explains displacement/ chemical affinity  Chemical Affinity:  Place copper in oil of vitriol (sulphuric acid)  copper dissolves  Place iron in the solvent  iron dissolves, copper deposits  It seems that iron has a stronger affinity that copper to oil of vitriol  Table of Chemical Affinity created by Étienne-François Geoffroy in 1718, Paris  Synthesis of empirical observation  Newtonian Chemistry: Chemical affinity indicates microscopic force – popular in France and England - A different Approach to Chemistry in Germany  Johann Joachim Becher and Georg Ernst Stahl: base study of chemistry not on Newtonian chemistry HPS211 Lecture 2 MAY17/2012  Both believed chemistry to be independent of physics, go back to alchemical system, and came up with the theory of phlogiston  Theory of Phlogiston  Cause of combustion (in general sense)  In combustion, phlogiston releases from matter to air  Combustion stops when matter runs out of phlogiston or when air is saturated with phlogiston  So after combustion, matter loses something  CLIMAX: discovery of “dephlogisticated air” (oxygen) - Joseph Priestley: nonconformist, discovered oxygen, interested in chemical studies  1774: important experimental discovery – discovery of New Air  Sun-burn red “mercury precipitate” in mercury-trough device  Generate a new air  Enable bright candle fire  Mouse survives long  Conclusion: air with greatest capacity for combustion  air with minimum density of phlogiston III. Chemical Revolution - Antoine-Laurent Lavoisier was intrigued with Priestley’s discovery  He refused the theory of phlogiston; his refutation:  From phlogiston theory, metal loses phlogiston after burning. When metal is weighed before and after burning, it gained weight. SO, metal must gain something, not lose something in the process  Metal combines with the new air of “oxygen” (acid generator)  Characteristics of Lavoisier’s Research Style  Highly quantitative, contrasting qualitative phlogiston chemist
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