5 of an
inch is left between its rim and the cover. An instant before putting
in the heat carrier--"pouring" it from the crucible--lift the cover and
agitator both together, so that the rim of the latter is level with the
sloping top of the instrument. The agitator then receives the hot ball
without shock, and no harm is done. If the ball goes below the agitator,
it is likely to injure the bottom of the cup. If, on taking the
temperature of the water before the immersion of the heat carrier, any
change is observed, either rising or falling, the direction and rate of
such change, and the exact interval of time between the last recorded
observation and the immersion, should be noted, in order to determine
the exact temperature of the water at the instant of immersion. The
temperature of the water will continue to rise as long as the heat
carrier gives out heat faster than the cell loses it. The rise will grow
gradually slower until it ceases, and the maximum can be very accurately
determined. Examples of the mode of using the tables, and of determining
the true temperature of the heat carrier at the instant of immersion
from the observations with the instrument, are given in the table on
pages 170 and 171 of this Journal for September.
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