Re: eosin/thymol (Why buy?)

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From:"J. A. Kiernan" <>
To:Gayle Callis <>
Date:Mon, 30 Aug 1999 00:39:20 -0400 (EDT)
Content-Type:TEXT/PLAIN; charset=US-ASCII

On Sun, 29 Aug 1999, Gayle Callis wrote:

> I find the concept of adding thymol to eosin interesting.  If the alcohol content is
> 70%, I doubt you will ever get growth, as this is the concentration preferred by those
> working in biohoods, to kill off bacterial and probably other contaminants and that is 
> why they spray and wipe down all working surfaces, before and after handling specimens or
> cell cultures.
> If you are working with aqueous solutions of eosin, you may have a problem, have seen
> this in stock1% eosin, before making up eosin phloxine solutions, even in the phloxine,
> but I can honestly say, I have never seen growth in any commercial preparations or 
> alchololic eosin solutions.  If you are not making up huge stocks, and use them fairly soon,
> plus storage in refrig, you may not need to use the thymol.  Vendors, what do you do?
> Your silence is overwhelming!

    The terrific overwhelmingness can only be a tacit admission
    that Gayle is (as usual) right, and thymol does nothing to
    increase the bactericidal action of 70% alcohol. Does it add
    to the price? The probable answer is Yes cubed.

    Why BUY a simple solution when the solvent and solute are
    more cheaply available?  You are paying someone else to
    do what you could do yourself for nothing. 

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1
   Phone: (519) 679-2111

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