larger container. Even in well-equipped labs, office wastepaper baskets may prove to be
practical and effective for this purpose. Any water forming from melting ice must be
removed from time to time.
In considering the length of time the ice mantle will be intact, note that water reaches its
maximum density at +3.98,C. This means that any water which is around 0,C and
becomes heated slightly will fall to the bottom of whatever container it is in. This is the
basis for stating that the Equiphase Cell should not be used beyond the time at which the
ice mantle floats.
Larger ice mantles can be preserved for a longer time than others and tend to melt more
uniformly, partly because they impede somewhat the circulation of warmer and heavier
water to the bottom of the cell.
(5) INSERTING THERMOMETERS (See figure 10). Any type of thermometer
may be used with the Equiphase Cell provided it will fit into the thermometer
well. Before inserting the thermometer, replace the cover over the top part of the
cell. Thermometers should be chilled before insertion.
With the thermometer inserted into the well, there should be sufficient ice water or
chilled liquid in the well so that the liquid level is above the top of the ice mantle. If the
thermometer is frequently removed and replaced in the well, it should be pre-cooled
before inserting so as to avoid excessive melting of the ice mantle.
(6) TEMPERING THERMOMETER LEADS (See figure 11). Ice and water may
be added through the opening in the cover to surround the top portion of the
thermometer well in order to temper the thermometer leads and prevent heat
conduction through the leads down into the well. It does not matter if this
tempering ice bath spills over the well provided that no ice chips are forced down
into the well.