You can use a thermistor to both heat the solution sample
and test the temperature. Or use a separate heater and still
use a thermistor sensor. Heat the fluid while monitoring
temperature. As you approach boiling the rate of temperature
rise will slow and then stop at the boiling point. You
should be able to determine the boiling point to under 1
degree C this way (depending on how you measure the (sensor)
and this has the added advantage of being able to stop the
heating as soon as boiling point is reached. If the
non-linear change of resistance is too hard to handle you
can use a platinum PT100 resistor which has a very
standardised linear change of resistance with temperature.
You could also cheat by using one of the digital temperature
measuring ic's that are available.

When heating you want to keep the sample small so the heater
can bring it to boiling essentially all at once.

I have seen brake fluid boiling point testers which seem to
work much along the above lines.


From: PHXSYS <PHXSYS@AOL.COM>
Subject: HOW TO MEASURE BOILING POINT


>I need some ideas for measuring the boiling point of
various fluids. The
>specific gravity of one fluid is approx 1.03, very close to
water. The
>accuracy I am looking for is +/- 3 %. I am looking for
creative options, the
>simplier the better.