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At 01:31 PM 12/12/2009, David Bradbury wrote:
James Enterline wrote:
At 04:00 PM 12/10/2009, David Bradbury wrote:
James Enterline wrote:
At 04:50 PM 12/9/2009, David Bradbury wrote [on detection of
tannic acid in the Vinland Map ink):
Both FTIR and Raman spectroscopy, which have been used on the
Vinland Map ink, are theoretically able to do the job, but neither
of the analysts responsible reported relevant peaks.
This may be simply because neither were looking for such
peaks. This is the whole reason I keep saying that someone should
do my experiment with a more open mind. Farther on this right below.
It seems clear from the way he abandoned the "alkyd resin" theory
that McCrone at least did approach his FTIR analysis with an open
mind; why do you assume he would not have reported tannic acid if he
had found it in significant quantities?
(rhetorical question!)
it was not until Walter McCrone applied FTIR in the 1990s that he
was able to make a fairly confident statement, namely that the
binder appeared to be based on gelatin made from skin.
Indeed, McCrone's confidence in that statement seems more justified
by spectroscopy than some other grandstanding of his. However, his
allusion to it as "the binder" is an assumption for which Olin
provides an alternative, that it results from hydrolysis of the
parchment collagen in situ.
By "the acid present due to the deterioration of an iron
gallotannate ink" But the iron is absent, and as far as we know, the
gallotannate is absent too. Also, I've seen a very large number of
medieval documents written with iron gall ink, and I don't recall a
single one in which the yellow stain of deteriorated ink appears to
be sitting on top of the parchment. In short, some fairly
extraordinary chemistry is required to create the conditions on the
Vinland Map from a starting point of an iron-gall ink, and despite
over 30 years of trying, Mrs Olin doesn't seem very close to
reproducing that chemistry.
Furthermore it is still not determinative between tannin and
gelatin for the following reason: His published spectrum (Fig. 3
in his 1999 paper) is cut off at the left just before one would
expect the peaks (dips) for tannin at 0.254 and 0.280 microns. It
would be interesting to know if his unpublished raw data includes
any points in that neighboring region. The Brown & Clark graph has
a corresponding vacuum at its right edge where tannin might appear.
...
I'll let you know if I learn anything helpful.
Thanks very much, David. And maybe Jacque has some contacts in
Chicago that could be helpful.
There's too much titanium underneath the surviving parts of the
black layer of the ink.
Who's to say how much is too much?
In general (though with massive variations due to the crude mixing
of the ink) there is a positive correlation between the amount of
black crust and the amount of titanium in the ink, but the Raman
analysis shows that the black carbon crust is definitely on top of
the anatase. There are simple explanations for this (the anatase is
in a layer that was applied to the paper before, or at least with,
the carbon) and there are one-in-a-million fluke explanations, such as:
The bleaching / transfer I suggested would leave the temporarily
re-fluidized ink vulnerable to lateral transfer of anatase under
any black film from mechanical action of the applying brush (as
well as diffusion).
Through the thickness of the tissue?
Through the thickness of the carbon, which would have been fluidized
with the binder. The anatase was throughout the tissue.
Furthermore, this episode could introduce a new plausibility for
Olin's and Cahill's ink-separation hypothesis. Carbon in the
original ink, now fluidized in an alkaline environment, might ball
up toward the center of the line.
So the ink fluidized enough for carbon to rise to the surface, and
anatase from the bleacher's tissue to sink into it, but not enough
to blur or feather. Neat.
That question would be best answered by an experiment, by someone
other than me. That's how science works.
The rare examples of mis-registration of the black layer could have
been caused by shear forces when the bleach brush swept a bubble aside.
Except that the one glaring example of mis-registration (the British
west coast) shows a clear structure, as if applied with a nibbed pen.
Well, that's a judgement--could an appropriately sized bubble have
lifted the structure and moved it with minimal distortion? We're
getting close to angels on a pin.
When everything dries out, any anatase deposited on the plain
parchment could fall off and the carbon could begin flaking away.
The evidence shows one or two factors (to be explained in a future
paper, or at the hypothetical conference) which tend to make that
scenario unlikely.
In any case, McCrone's tale of a forger sitting down and painfully
retracing, almost perfectly, a map he had just painfully fabricated
is too much to swallow.
It is until you consider the actual state of the map. If the British
Museum investigators were right in observing that the finest writing
tended to lack the black crust, and McCrone was right about most of
the black crust from the main lines being removed deliberately, then
the "painful" retracing could be a much more casual process,
applying the carbon fairly rapidly to the major lines and to random
points in the fine writing, then scraping most of it away,
particularly where it was badly matched with the underlying yellow.
It is too circular in motivation. The conclusion of forgery surely
came before the hypothesis of retracing.
Not really. The British Museum team were the first to hypothesise
retracing- but, inhibited by Yale from using high-powered
microscopes with bright light, they guessed that the carbon-like
black traces were underneath the yellow, not on top, which would
mean they were the remains of a mostly-erased preliminary graphite
pencil line, about a century before graphite pencils were invented.
That was just one of a number of factors (including the mismatch
between the ink's iron-gall-like appearance under visible light and
its very non-iron-gall-like appearance under UV and IR light; plus
the strange appearance of the parchment itself under UV) which led
them to declare the Map suspect.
OK, I'm glad for that information. I take back my harsh judgement of
McCrone based of his "battleship Nelson" metaphor as gloating after
his Shroud of Turin success.
And even before he could have lifted a pen, the forger had to sit
down and dope out the Latin cryptograms he was going to incorporate
into the inscriptions, an art not practiced since the middle
ages. And to what end nowadays?
Multiple cryptograms using multiple cryptographic systems.
No, multiple cryptograms (two) using the same single system.
To what end in the Middle Ages?
To secretly impress their indoctrinated colleagues with their own
creations, exactly the way the earliest creators of benign computer
viruses impressed their friends. They were followers or predecessors
of Trithemius.
Are they real, or figments of overactive cryptanalytical imagination?
I hope to have that decided by peer review of a paper I too am
working on. Meanwhile, don't jump to conclusions.
Jim
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