Allowing the flasks to sit for a period of time in the same environment allows for enough thermal cycling to result in significant condensation in the flask containing the DI water. Once established, the flasks can be used repeatedly over a period of years with no further preparation. The amount of condensation that results in both flasks will depend upon the ambient temperature. To increase the amount of condensation, simply place both of the flasks in a refrigerator for an hour prior to use. Photographs of two Florence flasks containing the different liquids are shown in Figure 1