On Tue, 2 Mar 1999, Priscilla wrote:

> have silver, mercury, and gold waste containers. I know how to
> precipitate the silver.  Can I do the same for mercury and gold?

  It is very easy to precipitate, redisssolve and purify your
  old gold chloride solutions. You end up with a somewhat smaller
  amount of perfectly usable gold chloride (HAuCl4) at almost no
  cost. Do the recycling as soon as your solution becomes a bit
  discoloured (greyish tinge). I have not bought any new gold
  chloride for more than 15 years. (I use it perhaps twice a
  month.)

   Ref: Stain Technol.  52: 245-248 (1977).

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1