The cooling curves of the salt solution and water obtained through the above experiment
(see Fig. 5) support our hypothesis. Indeed, there was a “flat” interval in the cooling curve of
water during which the water turned into ice. Shortly after this “flat” interval, the rate of decrease
in temperature increased considerably. In contrast, there was no “flat” interval in the cooling
curve of the salt solution and the temperature decreased at a slower rate from about –6 °C
onwards. The salt solution did not turn into solid at a single temperature but froze gradually over
more than 8 hours as it cooled along the ice/brine coexistence line. Consequently, latent heat and
sensible heat were gradually released along the way. The salt solution did exhibit supercooling
(which we will discuss in detail later) to a lower temperature as compared to the water, probably
due to the presence of dissolved salt.