Re: Alcohol followup - hygroscopicity of anhydrous ethanol

From:Philip Oshel

I'll have to check my OED, but whatthehell, it is now.
Your experiment is interesting, and counter to all I've been taught 
and read. This should be repeated, or perhaps a Quantitative Analysis 
student convinced to repeat the work. It would be nice if true.
But, along this line, an observation:
We keep our EtOH anhydrous by placing desiccant in the bottle. Saves 
lots of money over opening a new bottle every time we dehydrate 
tissue (we're an EM lab). If desiccant dust is an issue, the 
desiccant can be put in dialysis tubing and the ends closed. This 
should work for tissue processors, for those people for whom 
completely dehydrated EtOH is a necessity.


>Do you suppose "hygroscopicity" is a real word?
>In any case, in the recent discussion on alcohols it was stated by someone
>that 100 percent (anhydrous) ethanol would absorb water "very quickly" and
>so be non-100 percent. I have always believed that as well (after all, it is
>stated in most histology and EM books), but decided to test some 100 percent
>that had been exposed to air in a stain line for about two weeks. With my
>hydrometer it tested at 100 percent. Of course it is not too humid in
>Atlanta this time of year (about 35 percent), but if anhydrous ethanol is
>supposed to be hygroscopic you would think it would have taken in a little
>water in the two weeks it has been exposed. As it is ,it has appeared to
>take in NO water. Any thoughts or comments?
>Tim Morken
>CDC, Atlanta

Philip Oshel
Supervisor, BBPIC microscopy facility
Department of Animal Sciences
University of Wisconsin
1675 Observatory Drive
Madison,  WI  53706 - 1284
voice: (608) 263-4162
fax: (608) 262-5157 (dept. fax)

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