Isolating and Weighing Precipitates

To disintegrate the filter paper, the rinsed filter paper containing the precipitate is folded and placed into a preweighed porcelain crucible and the crucible is heated, first cautiously with a cooler Bunsen burner flame, so as to dry and char the filter paper, and then with the full heat of a Meker burner. For this final ignition step, the crucible should be tilted to one side and partially covered with the crucible lid so that the burner flame can be directed to the bottom of the crucible, thus avoiding engulfing the 

Wil Kastning of the Nebraska State Agriculture Laboratory filters barium sulfate precipitates using filtering crucibles and a vacuum system while performing a gravimetric analysis of fertilizers for sulfate content. 

FIGURE 3.8 Rinsing the precipitate and filter paper with distilled water from a squeeze bottle. 

FIGURE 3.9 A crucible tilted to one side, with lid partially covering the opening. This allows the burner flame to be directed to the bottom of the crucible and air to circulate into the crucible. 

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