On Wed, 14 Oct 1998 NTT@shcc.org wrote:

> Does anyone have a recipe for 4% paraformaldehyde that they would be
>willing to
> share?  Hopefully someone will be able to get back to me by the end of
>today.

  Add 40 g paraformaldehyde and 6.5 g dibasic sodium
  phosphate (Na2HPO4) to about 750 ml of water. Heat
  to 60C, with magnetic stirring. The slution should
  become transparent when it reaches 60C. Add 4.0 g
  of monobasic sodium phosphate (NaH2PO4.H2O) and
  let it cool down. Add water to one litre.
  Check the pH (7.2-7.4), adjusting if necessary.

  Note that this solution and others like it are
  NOT "4% paraformaldehyde." They don't contain
  any paraformaldehyde at all, only formaldehyde
  (actually methylene hydrate) formed by
  depolymerization.

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