[Phys-L] Re: Caloric

[Gary Karshner <gkarshner@STMARYTX.EDU>]

Jim,
Antoine Lavoisier used it in his "New Chemistry" to explain heat. He
defined he chemical elements and in many cases gave them there modern
names, and defined heat as a fluid "caloric." His explanation gave us much
of modern chemistry, and replaced phlogiston an element like substance heat
with caloric a fundamental substance. For example oxygen replaced
dephogistonated air.
         I think most physicists think of the history of science as a
linear process; Galileo, Newton, D'Alembert, Laplace, etc. Each one
building on the previous one. The history of thermodynamics and statistical
mechanics is anything but linear.
         One of caloric theory's great high points is that it along with
the atomic theory could explain the changes of phase. Billiard ball atoms
stuck together to make molecules and in solids the molecules stuck to each
other. As one forces caloric between the balls they are eventually
separated enough to slip over each other and you have a fluid or become
completely detached and you get a gas.
         The the french atomist did not like Rumford's kinetic theory
because there was no places this picture for their solid atoms to be in
motion. They derided it as the "old theory" as it harped back to Newton's
idea of fundamentalness of motion. Of course caloric fluid is where the
image of heat flowing comes from and is still argued about on this list.
Old ideas die hard.
         Rumford married Lavoisier's widow. The union was not a happy one,
unlike her first marriage. There is a famous portrait of Lavoisier by
David. It is typical of 18th century portraits as a man surrounded by the
things he holds dear see:
         http://www.artchive.com/artchive/D/david/david_lavoisier.jpg.html
         Sadi Carnot conserved Caloric to develop his Carnot cycle.

Gary


At 09:41 AM 6/4/2005 -0600, you wrote:
> A little tutoring if you will:
>
> Who invented the idea of caloric?
>
> What was the motivation?
>
> TX
>
> Jim
>
>
> Jim Green
> mailto:JMGreen@sisna.com
> http://users.sisna.com/jmgreen
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