Experiment 4: Boiling stones
In this experiment, I used an up-to-date product found in a standard catalogue, which were “boiling stones” made of pure Teflon. (Aren't there worries about not using the same materials used by the historical scientists?) Inserting some boiling stones into water boiling in a glass beaker produced extremely vigorous bubbling. Observe how violently the surface of the water breaks, and how the boiling stones are continually covered in a film of vapour. This vigorous boiling brought the temperature by more than a degree. In the next part of the clip, the boiling stones were placed in the water before heating. This produced very active bubbling from around 90°C, and vehement boiling from around 98°C. The maximum attainable temperature was only around 99°C. Next, in the trial with a ceramic mug, the boiling temperature was brought down by around 3 degrees.
Watch a video clip showing this experiment (1 min. 20 sec.)
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