I want to thank Brian for pointing out that there are no stupid questions,
too often some ridicule accompanies answers.
Bryan is correct in that hematoxylin dissolves in water, however it is
often contaminated with bark, crystals and other wood portions that can be
extracted with alcohol. 
In some cases the alcohol may facilitate the penetration of the solution.
You can ripen hematoxylin solutions simply by exposure to the oxygen in the
air to form oxyhemateins. This was the original time honored method. The
problem with most oxidizers is that they oxidize to form a mixture usually
di- and trioxy-hemateins to give colors (with potash alum hematoxylins) of
Cambridge blue to blue black. If the oxidation is carried further then the
product of tetroxy-hematein is usually brownish and pentoxy-hematein is
colorless. This can also be seen with iron hematoxylins. That is why
hematoxylin solutions have a limited life and as they get beyond their
useful life the staining becomes weaker.
One way to overcome this overoxidation is to store the ripened hematoxylin
in a large separating funnel with a layer of mineral oil on the top to
prevent further oxidation. Then simply use the stopcock on the bottom of
the funnel to remove the amount of hematoxylin solution that you want. This
can be a bit messy but works well.
An alternate is to purchase dioxyhematein and use this, there are several
formulae that have done so on the past.
Barry


At 08:57 AM 10/20/2001 -0700, you wrote:
>
>----- 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
>
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