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From: Corey Brand
Date: Fri, 3 Apr 1998

I've just placed an order for a soxhlet extractor with a glass
extraction thimble. I decided on the glass thimble because the
catalog indicated the cellulose ones were not advisable for use with
strong alkaloids. Since I plan to use the apparatus for the
extraction of plant salts from ash, I figured it would be best not to
use cellulose.

However, it has just occured to me a glass thimble might be too
porous for the fine ash and allow some of the insoluble elements to
seep through. Does anyone on the list have any practical experience
with a soxhlet apparatus, and could they give me some tips?

Thanks!

Corey

Date: Sat, 04 Apr 1998
From: John H. Reid III

Corey:

I have done a lot of work extracting salts from plant ash using a
soxhlet. I have found that using a paper coffee filter works best. I am
able to get more ash into the paper than using the glass thimble
supplied with the soxhlet. I like to use the "Natural Brew" brown coffee
filter paper that has not been bleached. Generally I wrap the filter
holding the ash in a second filter, drop it into the soxhlet and away we
go :)

Kind Regards
John H. Reid III

Date: Sun, 5 Apr 1998
From: Beat Krummenacher

Cellulose can be used instead of glass to the extraction of plant ashes in
the Soxhlet. It even functions, if one takes an ordinary coffee filter,
fills in the ash and locks with staples.

There is however a much simpler method: One gives the ash in distilled
water and boils shortly under stirring. After cooling down it is filtered
by suction and rinsed with distilled water. The residue can be boiled with
fresh water and filtered by suction once more. However during the second
decoction hardly more soluble salts are received.

Lapis