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Re: A question



While surveying a collection of books for preservation evaluation purposes =
I came across a volume that had powder sprinkled throughout.  Included was =
a note on a slip of paper that indicated the powder was talcum.  What =
might have been the reason for using the talcum?  What is the best method =
for removing it?  I ask because after brushing the powder away very =
carefully there seemed to be a residue left behind on the page.

- Walter Cybulski
National Library of Medicine

>>> <info@papertrail.on.ca> 02/29/00 10:55PM >>>
If you can extract a bit of the powder onto some clean paper (waxed paper
might be better), put a drop of vinegar on the powder; bubbling (generation=

of carbon dioxide) would indicate that it is most likely sodium bicarbonate=

(baking soda) or calcium carbonate (chalk). If you can't get enough =
powder,
though, it might be difficult to observe the bubbling. Also, make sure =
that
your "clean" paper does not itself cause bubbling!
You can tell these two powders apart because baking soda will dissolve
completely in a moderate amount of plain water, but chalk does not =
dissolve
at all.

Other substances fizz in vinegar too, but these two would be the most =
likely
candidates.
If it does not fizz, it might be, as you suggest, mould or fungus, but it
could also be talcum.
-Kevin Martin
 the Papertrail

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