Re: chrome-alum gelatin (conc. of ca-g)

From:Sunil Thomas K <sthomaska@yahoo.com>


I left out he concentration in the previous message

 solution that is usually prepared in our contains
1.25 gm gelatin and 0.125 gm pot.chromium sulphate in
250ml d/w. I doubled the amount of both....

sunil
 
--- Connie McManus <conmac@cc.usu.edu> wrote:
> 
> 
> 
> John,
> 
> This is an interesting experiment, but I have never
> seen where my gelatin
> solution cannot be dissolved. I do it every day by
> putting it in my
> waterbath. I works Jim Dandy-- I don't have sections
> falling off.
> Furthermore, I have never seen any kind of
> contamination, fungal or
> bacterial.  With all due respect, John, my
> experience does not mesh with
> what you have said, so, below, are some questions
> about your experiment.  
> 
> At 03:54 PM 7/30/01 -0400, J. A. Kiernan wrote:
> >On Sat, 28 Jul 2001, Sunil Thomas K wrote:
> >
> >> I have a question regarding chrome alum-gelatin
> used
> >> for subbing. It gets very viscous when
> referigerated
> >> (difficult to pour out from the glass bottle. 
> >> Is this solution warmed before slides are dipped?
> >
> >A smart observation, Sunil Thomas K !
> >Chrome-gelatin solutions must be used soon after
> >making. They cannot be stored in a fridge or
> >anywhere else. They cannot be diluted either.
> 
> What is the connection between this and Sunil Thomas
> K's observation that
> the solution is viscous when refridgerated?  That is
> the nature of cold
> gelatin in my experience. As soon as the gelatin
> comes to RT, it is liquid
> --- well, less viscous.  Put it back in the fridge
> and let it come to that
> temp, voi la, viscous gelatin again.
> 
> >
> >Chrome gelatin solutions quickly become infected
> >so they should be used right away and not stored.
> 
> I thought the reason for adding the chrome in the
> gelatin solution was to
> prevent contamination (or infection).  I have used
> gelatin solutions
> without it and they DO become contaminated no matter
> how aseptic you treat
> them.  I have never ever had any problem with this
> since adding chrome
> sulfate to my gelatin (keep in mind, I never allow
> anything non sterile to
> touch the gelatin, either).
> 
> My last question is...are we talking about the same
> formula?  My formula is
> 1.5 g gelatin in 300 mL DI water and 4 mL 4% chromic
> sulfate, autoclaved
> for 15 minutes on a lq cylce and stored in a tightly
> sealed container.  I
> have always called this Chrome Gelatin (the person
> who clued me in to this
> was from Bern, Switzerland and that's what she
> called it).
> 
> seeking enlightenment *g*
> Connie McManus
> 
> Veterinary Diagnostics Lab
> Utah State University
> Logan, UT
> USA
> (435) 797-1891
> fax (435) 797-2805


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