----- Original Message -----
From: "Doug Wade" 
To: 
Sent: October 19, 2001 2:41 PM
Subject: Hematoxylin recipes


> Hopefully these aren't too stupid questions:

There is no such thing!

>
> Why are some oxidizers chosen for various hematoxylin forulas.

Mostly it is the personal preference of the person publishing the formula.
Modern authors almost always recommend sodium iodate.

> I'll see sodium iodate or mercuric oxide used but never oxidizers like

The commonest one is sodium iodate at a maximum of 0.2 grams per gram
hematoxylin.  Mercuric oxide is almost never used today (and really
shouldn't be at all) because it ends up in the public water systems and can
contaminate rivers and such.

> hydrogen peroxide or chromium trioxide (chromic oxide) etc.

I seem to recall that one variation does use hydrogen peroxide.  Probably
chromium trioxide could be used as well. but sodium iodate is so very
effective and convenient there would be little point.  In reality, the
chemical used as a source of oxygen is pretty well irrelevant, just so long
as oxidation takes place.

>
> Why do some recipes (IE Delafields Alum Hematoxylin) ask for absolute
> alcohol yet other ingredients in the forumla are aqueous solutions?

This is almost certainly for historical reasons.  Hematoxylin began to be
used in the late 19th century.  Purified hematoxylin powder was not
available at the time.  It was common practice to extract the dye from
logwood chips into ethanol.  The maximum concentration was about 10%, and
this alcoholic solution was used to calculate the amount of dye.  Through
use it has become common to think that hematoxylin requires alcohol to
dissolve at the concentrations needed for strong solutions.  In fact it
dissolves in water well enough (see Lillie's strong formula).  Of course, if
you remove the ethanol it won't be Delafield's anymore.  It would be someone
else's modification of Delafield's.  Alcohol free formulae are quite common.


Bryan Llewellyn