1. Clean vacuum-desiccators and cover the bottom with water (about 1 cm). Place the 'F' flasks inside the desiccator. As many flasks as will fit without spilling the soil or blocking the opening of another flask may be placed in each desiccator (about 13 flasks). Include one blank (empty Erlenmeyer flask) in each desiccator.
2. Place a 100-mL beaker in each desiccator. Add a few glass beads and 40 of alcohol-free chloroform. Use gloves and work in the fume hood at all times when working with chloroform. Close the desiccator with the lid (use some Lubriseal or Vaseline for good sealing).
3. Start the water aspirator, check the vacuum suction, then attach the hose to the desiccator. This will create a vacuum in the desiccator, causing the chloroform to boil and evaporate, and saturate the desiccator atmosphere. Allow the chloroform to boil vigorously for 5 minutes. Then (first) close the vacuum route by sealing the desiccator (by turning the top), and then stop the water aspirator. The vacuum will suck water into the desiccator if you turn off the water before sealing the desiccator. Reapply the vacuum 3 times over the next hour. The chloroform may not boil after the first time. Allow the fumigation to proceed for 2 days.
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