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Name: Mark L.
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: N/A 


Question:
Why does the weight of sediment (dirt) mixed with water, strained through various brands of paper towels, and oven dried for 20 minures (250F), not correlate with the remaining residue in the specimen jars?
Does the dirt adhere to the water molecule, evaporate & then seem to dissappear?



Replies:
Mark,

Do you include the amount of soil stuck to the paper towels in you calculations.

The heating of the sample certainly may cause something in the sample to volatilize and "disappear", leading to decreased sample weight.

David R. Cook
Atmospheric Section
Environmental Research Division
Argonne National Laboratory


No, more likely you have just dissolved some salts or other soluble solids. E.g., if you took table salt, stuck 1 gram in in a jar, mixed it up in water, and dried it, you'd pretty much have 1 gram at the end. If you took that same 1 g of salt, mixed it up in water, strained it through paper towels, you'd be lucky to have anything left. Lots of other minerals dissolve at least partially in water, so it's no surprise that you would have less "dirt" left over after dissolving and straining it.

Don Yee



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