While I believe the Shroud image to be a contact scorch on linen, due to chemical dehydration and yellowing of linen carbohydrates, I still try to keep an open mind as to the source of heat.
Given that a dead body does not produce sufficient heat to scorch linen (for which a temperature of 200 degrees Celsius or more is required) then the thinking so far has been that an effigy of a real person, e.g. a bronze statue, was deployed. However, I'm as conscious as the next man of the practical difficulties of imprinting successfully off a life-size effigy. Mistakes would be costly, given the price of quality linen,
So this morning, I got to wondering about alternatives to metal templates that have been heated, say, over coals. Might an exothermic reaction using a chemical have been used instead - but a common one available in medieval times?
I got to thinking about quicklime, chemical name calcium oxide (CaO) and googling quickly led to this fascinating WordPress site:
No sooner said than done... (Poor choice of title methinks - it's calcium oxide that is the chief interest, not the precursor calcium carbonate).
Addendum: for those interested in the entire limestone/quicklime/slaked lime/limestone cycle, here's the full works.
1. Take natural chalk or limestone (calcium carbonate). Kiln-roast to decompose, driving off CO2 gas to leave residue of quicklime (calcium oxide)
Calcium carbonate + strong heat = calcium oxide + carbon dioxide gas
2. Slake the quicklime with water to get slaked lime (calcium hydroxide):
Calcium oxide + water = calcium hydroxide (highly exothermic reaction)
3. Slow reaction (months, years even) between slaked lime and CO2 of air to revert back to calcium carbonate:
Calcium hydroxide + CO2 = calcium carbonate + water
|Lime kiln, La Rochelle, France, reckoned to be 2nd - 6th century. Much is now missing, like the top part, usually hemispherical, that served as a hopper for the limestone.|
Update 10:50am, 20 June
Hey, look what's just turned up. A 13th century French recipe (originally) for cooking without fire, using the heat from slaking of quicklime with water. (The same reaction is still being used today in camping kits).
Click on image to enlarge. It's the last paragraph that is especially interesting ("to cook meat without fire"). The medieval French and no doubt others knew all about the extraordinary properties of quicklime and uses to which it could be put - notably an easily portable source of instant heat, needing only the addition of a little water - the stuff that extinguishes conventional fires.
Further thoughts - 11:40am
OK, so it's blue sky thinking at this stage. Suppose the geometry were as follows (top down): corpse, linen sheet, bed of quicklime.
Now where's the MAIN image likely to be formed when moisture from the drying corpse meets quicklime? Answer: not on the conventional interface between body and linen, but on the OPPOSITE side. In other words, moisture would need to migrate through the thickness of the linen first, and only when it meets the quicklime would heat be generated to create a thermal imprint via chemical dehydration of the linen. Might this mechanism go some way towards explaining the curious superficiality (to say nothing of fuzzy character!) of the TS image?
What's being conjured up here is a scenario that might be described as 'reverse-side imaging'.
Might it even help to explain (don't ask me how) the "second face", that being where the body IS in direct contact with the linen?
More thoughts: 13:00
OK, so we know from the YouTube clip that the reaction between quicklime and water generates sufficient heat not just to bring water to the boil, but to convert it instantly to steam. That suggests a temperature considerable in excess of 100 degrees C, which is needed, of course, to produce scorching of linen. But how much greater?
The wiki entry on calcium oxide provides some clues (my bold/italics)
"Quicklime is also thought to have been a component of Greek fire. Upon contact with water, quicklime would increase its temperature above 150 °C and ignite the fuel (ref)..
Because of vigorous reaction of quicklime with water, quicklime causes severe irritation when inhaled or placed in contact with moist skin or eyes. Inhalation may cause coughing, sneezing, labored breathing. It may then evolve into burns with perforation of the nasal septum, abdominal pain, nausea and vomiting. Although quicklime is not considered a fire hazard, its reaction with water can release enough heat to ignite combustible materials."
Me again: the temperatures quoted are maybe lower than those required for rapid scorching from a heated metal template, but in the scenario imagined here, it is a slower process that gradually produces a visible yellowing of linen and final image production. What's more, the production of the alkaline calcium hydroxide would almost certainly allow chemical dehydration and yellowing to occur at lower temperatures, due to base catalysis by hydroxide (OH-) ions..
And finally, to bring this shroudological derring- do to a close, none too soon some might feel, one has to ask the crucial question: is the idea testable?
Why yes. The first thing to do is buy in some quicklime, which I see is available though Amazon.
One then gets a jar with a well-fitting lid. One places a bed of quicklime on the bottom. One then adds a layer of linen, and then adds something that is organic of high moisture content, to model a human corpse, preferable with intact skin. It could be a chicken leg or wing, say. One then covers with a second layer of linen, and adds more quicklime on top. One then screws the lid on firmly, to exclude moist air and CO2 (which would inactivate the quicklime) and then leaves the jar. For how long? No idea. It might be days, or it might be weeks. Ideally one ought to set it up in such a way that the progress of any imaging can be monitored without having to open the jar or disturb the contents. A thermometer inside might also be a wise precaution.
Postscript: This posting was quickly spotted by shroudstory.com while still in gestation (yes, I generally take a working day to assemble a posting by instalments in 'real time', it being my preferred MO), and appeared under the title: "Maybe a new image hypothesis"
Sadly, the discussion there was side-tracked (yet again) by someone proselytising his own "limestone" scenario, one I don't pretend to understand, given his long-expressed belief, predating current references to ammonia as well, that limestone is an alkali. Things went rapidly into the mire, given (one suspects) that a lot of folk do not know (or care) that limestone and quicklime are two entirely different substances. Limestone is natural, and a major surface rock. Quicklime is man-made (yes, from limestone) and is a vicious chemical that burns skin and eyes, due to its avidity for water, and the heat that is generated when it reacts with that water, forming calcium hydroxide, a strong alkali. It is also increasingly apparent that folk on that site plunge into comment and indeed criticism without bothering to check with the originating site (this one!). At least two commentators appear to imagine that the corpse is in direct contact with the limestone, and would become attacked and decomposed. They have had to be disabused of that idea. The corpse is wrapped in linen, and the shroud and its contents placed on or in a bed of quicklime. The putative scorch imprint is formed when moisture from the corpse migrates across the thickness of the linen, and on meeting quicklime on the outside, reacts instantly with the calcium oxide to generate local heat and alkali. It is the combination of the heat and alkali that produces the thermal imprint on the OUTSIDE of the shroud, leaving the body inside largely unaffected (while slowly drying out, and perhaps mummifying).
Speaking of which (shroudstory.com) today's posting has the title: Discussion about the Pray Codex and its relation to the Shroud of Turin is over".
(A Guest Posting by "OK", a Polish Shroud scholar).
Am I the only one to be overawed by the sophisticated nature of the probability calculations that led to OK's conclusion, namely that it is the Shroud of Turin that is being displayed in the late 12th century (1192-1195) Pray Codex (outside the range of the Shroud's radiocarbon dating, 1260-1390)?
Taking a leaf from OK's book (of probability and statistics) I've just made two amazing discoveries.
First I shuffled a pack of cards, then dealt them from the top of the pack onto a table. The resulting order in which the cards emerged had an amazingly small probability, one that was 1 in 52 factorial (52!), i.e. 1 in 52x 51x 50x 49 ... x4x 3x 2 x1. See link for the infinitesimal answer from a calculator. Isn't that just incredible, though I have to admit I thought that probabilities were supposed to be computed BEFORE one did one's trial, not after. ;-)
I've also been experimenting with his "points of correspondence" criteria for determining whether two items are related or unrelated in space and time, and have made yet another amazing discovery.
Look closely at the two pictures. (Naturally, I chose the one of Queen Victoria that had a Mona Lisa-like enigmatic smile, the way that textile restorer Mechthild Flury-Lemberg and historian Ian Wilson chose the Pray Codex with its "L-shaped poker hole". (Selection bias gets one ahead of the game when wishing to make claims for real as distinct from spurious cause-and-effect relationships). Notice anything else about the pictures? NEITHER OF THE TWO LADIES HAS A FULL SET OF DIGITS (either a thumb or finger is missing). And as everyone knows there are no thumbs on either the Shroud image or the Pray Codex which simply HAS TO BE TELLING US SOMETHING, and COULD NOT POSSIBLY BE ACCIDENTAL.
Yup, there's no doubt about it. Queen Victoria could not have been born in 1819 as historians would have us believe. She must have been around much earlier to have served as Da Vinci's model for the Mona Lisa, painted 1505-1507.
See my critique from two years ago and that of others of the claims made for the Pray Codex, with links to a particularly long and trying discussion on shroudstory.com .(It was clearly a waste of time, given the way that folk return time and again to their entrenched positions, failing to acknowledge the points that one has researched, e.g. that what is being interpreted as a shroud with a herring bone weave and "poker holes"is in fact a sarcophagus lid with a stepped pattern).
OK has come back to someone with this comment:
Other similarities that could be mentioned include a seemingly high set chest and long arms