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Re: Calorimetry is alive and well



At 14:50 9/24/97 +0000, you wrote:

.. Calorimetry - heating something and watching what
happens to the temperature - is still alive and well in solid state
physics, as well as in chemistry. ...

Think of differential scanning calorimetry as two simultaneous
calorimetry experiments. A known quantity of a known material (like
Al2O3 or quartz) is heated at a constant rate. A second material to be
studied is simultaneously heated at the same rate. As the heat is
applied, the temperatures increase (hence "scanning"). The difference
between the temperatures of the two objects (hence "differential") is
related to their specific heats (hence "calorimetry"). If the specific
heat of the first is known, the second can be easily determined. This
is particularly useful at either high or low temperatures, where it is
hard to thermally isolate the sample from its surroundings
...
Timothy J. Folkerts

One could criticize an experimental setup like the one described.
It is greatly to be preferred that the heat input to each object
is modulated in order to make the respective temperatures as far
as possible identical.
This has advantages: you can measure electrical quantities
with great precision, and keeping the test object and the 'standard'
object in the same environment ( as far as possible) is the preferred
arrangement for controlling extraneous variables.

Regards

brian whatcott <inet@intellisys.net>
Altus OK