Dear Heike,

  You raise a couple of questions, so here are a couple of answers.
  The first (long) is about names and is, IMHO, correct. The second
  answer (short) is merely a little more speculation about the
  deposits on your slides.

On Wed, 13 Sep 2000, Heike Grabsch wrote:

> - I have already seen precipitates coming directly from haemalaun (or is
> it called haematoxylin? please forgive me for my ignorance),

   Haematoxylin is the compound you dissolve; it is colourless when
   pure. It is oxidized to haematein, which is yellow and can form
   coloured complexes with many metals. When the metal is aluminium,
   the solution is called a haemalum. It is commonly the colour of
   red wine, but may be purple, depending on the formulation. (pH and
   amount of excess aluminium ions affect the colour.)
   Solutions such as Ehrlich's, Delafield's, Mayer's, Harris's, Gill's
   etc are all haemalums, but they are regularly wrongly named as
   "haematoxylins."  With other metals the dye is also haematein, not
   haematoxylin, but everyone says "Weigert's haematoxylin",
   "phosphotungstic acid-haematoxylin" etc, and many live with the
   illusion that the H in H&E is for haematoxylin rather than haemalum.

 Next paragraph is small-print stuff.

   The system of names is complicated by variations in spelling. The
   haem- is simplified to hem- in American English. In German, many
   informal chemical names end in -ine rather than -in or -ein, and
   the ending -ine is used for many compounds that in English
   should end in -in. The French are as bad, with a propensity to
   make all the words end in -ine. These suffixes are chemically
   significant in English usage, and modern writers from Continental
   Europe now follow the same principles, but plenty of anomalous
   spellings are still frequently seen because of uncritical use of
   words taken from German or French into English. The Colour Index
   (CI) itself uses the archaic German "haematine" for haematein,
   probably retained un-noticed for 50 years, but modern German
   writers on dye chemistry (Heinrich Zollinger is pre-eminent)
   use the convention of -ine for bases (amines), -ein for compounds
   in which unsaturation is significant, and -in for uncharged or
   anionic dyes. Haematoxylin and haematein are uncharged (but can
   form anions). Eosin and phloxin are also anionic dyes, so it is
   wrong to put an -e on the end of either. Thionine is a basic
   (cationic) dye, so it should never be spelled as "thionin,"
   and the same is true of all dyes with "fuchsine" or "rosaniline"
   as parts of their names. Even acid fuchsine (an anionic dye)
   gets a terminal -e because it is formed by sulphonation of a
   basic parent compound.

   Returning to haemat-    Don't ever confuse any of these
   compounds with haemoglobin and some of the products of its
   degradation, such as acid haematin (formalin pigment). There
   is an excellent stain known as Baker's acid haematein that
   uses chromium as the metal component. It is nearly 60 years
   old and its histochemistry was sorted out nearly 40 years ago.
   It displays structures rich in choline-containing phospholipids,
   including mitochondria and myelin sheaths of axons.

 End of small-print stuff.

> (BioGenex) as chromogen, rinse in dist. water, 90 sec Mayer's,

    Could the rinse in water after buffered AEC be insufficient?
    If some phosphate buffer carries over into the haemalum
    there could be precipitation of aluminium phosphate, with
    attachment of haematein to the Al ions.

    'nuff said.

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