On Sun, 8 Nov 1998, B.A.Murray wrote:

> ... How do you dispose of your hematoxylin with mercuric oxide?

  The mercuric oxide used to do the oxidizing hardly dissolves in
  water (0.005 g per 100 ml) and the product of its reduction,
  mercurous oxide, is even less soluble, even in acids. [Data
  from Lange's Handbook of Chemistry]  Consequently nearly all
  the mercury used in making a Harris-type haemalum remains
  in insoluble form. If you filter the product, the evil
  mercury is in the filter paper. This can be set aside and
  allowed to dry, making a very small object for safe disposal.
  If you do not filter the matured staining solution, the
  mercury will accumulate in a sludge at the bottom of the
  bottle. If it's a small, cheap plastic bottle, it can be
  sent for disposal. If it's a big, expensive glass-stoppered
  vessel, you'll need to wash it out and collect the
  poisonois sludge in filter paper.

  The staining solution itself (with no insoluble material)
  does not contain mercury. It can and should be used repeatedly
  until its potency diminishes. Rinsing solutions are therefore
  harmless too, because they do not contain mercury.

  All this trouble with mercury and silly safety officers is
  most easily avoided by not using the accursed element. Iodate
  is traditional and a lot less toxic. All the standard textbooks
  have mercury-free recipes for haemalum staining solutions.

> Another question,how many of you still make your Hematoxylin?

    If you buy the solution you pay for the transportation of
    water, glass and protective packing. A single small order
    of cheap solid chemicals, all minimally hazardous, has to
    be a big saving. Here in prosperous SW Ontario no academic
    outfit (relying on research grants) could afford to buy
    pre-made solutions of uncertain composition. A laboratory
    with generous government or other external support might be
    able to afford the luxury of saving one man-hour instead
    of making enough staining solution to last a few months.

 This doesn't answer your "how many" question, but it might
 encourage others to make up their own routine alum-hematoxylin
 solutions. You can do it if you can read, weigh and measure
 volumes.

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