Download NATS 1760 Lecture 13

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