alternative hoyer's solution

[Anne Schot]

----- Begin forwarded message 11-Apr-96


In January there was a lot of discussion on TAXACOM about the ingredient Arabic
gum for Hoyer's solution. At that time I was just trying to make a new solution
for our bryology department. Here's my solution:

METHODS USED TO MAKE ALTERNATIVE HOYER'S SOLUTION

Formula for alternative Hoyer's solution using powdered Arabic gum:

Arabic gum (powder)             40 g
Distilled water                 80 ml
Glycerin                        20 ml
Chloral hydrate                 30 g  *

Dissolve the Arabic gum in destilled water by stirring it on a magnetic stirrer
for 48 hours.
Add the glycerin and chloral hydrate.
Carefully heat the mixture (to about 60 degrees Celcius) and filtre it through
a Buchner funnel with a piece of clean, roughly woven cotton cloth, to remove
the biggest particles.
Pour the mixture into a tall narrow glass cylinder and let it rest for two
weeks so that the small particles sink to the bottom.
The top part which is an almost clear solution can now be used to mount mosses.

* The amount of chloral hydrate is a lot less than in the original Hoyer's
formula. This has the advantage that the mounted material doesn't become too
clear.


The use of powdered Arabic gum as done above has the disadvantage that the
final solution remains a little cloudy.
We found that we could still obtain granular Arabic gum from a chemical
supplier in the Netherlands. But it should be no problem to find a supplier in
your own country that distributes products from the firm "CHROMA gesellschaft".

We ordered:

Gummi Arabicum, granuliert      CHROMA nr. 3G 112

from:   Brunschwig chemie b.v.
        P.O.box 70213
        1007 KE  AMSTERDAM
        The Netherlands

Good luck with making your own moss mounting medium!

        Bertie Joan van Heuven
        Rijksherbarium/Hortus Botanicus
        P.O.box 9514
        2300 RA  LEIDEN
        The Netherlands

        EMAIL:  IN%"HEUVEN at RULRHB.LEIDENUNIV.NL"


----- End forwarded message