Klarinet Archive - Posting 000263.txt from 2005/08

From: George Kidder <gkidder@-----.org>
Subj: RE: [kl] salt and mold growth
Date: Mon, 15 Aug 2005 10:04:25 -0400

At 10:19 PM 8/14/2005, Ed Lacy wrote:

>According to an experiment reported in the Instrumentalist Magazine in
>about 1962 or '63, in a closed environment near water saturated with
>salt, the humidity remains at exactly 50%. I didn't do the experiment
>itself; I'm only reporting what I read. That was where I first heard of
>the possibility of keeping reeds or reed cane in such an environment. I
>tried it for a while, but found it more trouble than it is worth.

I have recently had to look this up for reasons having nothing to do with
clarinets. According to Greenspan (Greenspan, L. 1977. Humidity fixed
points of binary saturated aqueous solutions. Res. Nat. Bureau Stand.
81A:89-96) the relative humidity of air in equilibrium with a saturated
solution of sodium chloride (table salt) is 75.74 +/- 0.14 % at 20 degrees
C, and varies less than +/- 1% over the temperature range from 0 to 80
C. 75% is not really very dry. We can assume that the "dry" salt absorbs
moisture, but unless it dissolves in that moisture, it would have a lower
Aw (in Bill's terms) than a saturated solution. There are salts which
would produce 50% as a saturated solution (magnisium nitrate or sodium
bromide come close) but I would NOT recommend keeping these in the vicinity
of something which I was going to suck on.

George W. Kidder III, PhD
Senior Scientist, Instrumentation Officer and Director of the Animal Program
Mt. Desert Island Biological Laboratory
Salisbury Cove, ME

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