Brew up a miracle for fun and profit, in the comfort of your own kitchen.

The blood, in a phial in a church in Naples, is reverently turned over several times during services every few months. It has seldom failed to liquefy since 1389. (It has also accidentally liquefied when the monstrance holding the phial was being cleaned!) Three Italian scientists are quoted in the Skeptical Inquirer (Vol 16, No 3, Spring 1992, p236) as having duplicated the “blood.” The relevant data (Nature vol 353, p507) are:

“To a solution of 25g FeCl3.6H2O in 100 ml of water we slowly added 10g CaCO3, and dialysed this solution for 4 days against distilled water from a Spectra/por tubing (parchment or animal gut works just as well; a simple procedure1 even allows us to avoid this dialysis step). The resulting solution was allowed to evaporate from a crystallisation disc to a volume of 100ml (containing about 7.5% of FeO(OH). Addition of 1.7g NaCl yielded dark brownish thixotropic sol which set in about 1 hour to a gel. The gel could be easily liquefied by gentle shaking, and the liquefaction-solidification cycle was highly repeatable.”

Thixotropy is the property that interests us, that of setting to a gel or shaking to a sol(ution). I had always imagined the warmth of the priest’s hands was the main secular reason for the liquefaction, but apparently not.

I rang my old chemistry master, Alex Wooff, in Christchurch, to find out what the dialysis would involve. Dialysis is a differential diffusion through a membrane. You put the mix in a tube (rather like a sausage skin with the ends tied, I gather) and the tube in a tank of distilled water. Certain acidic by-products pass out through the tube walls, and what you want stays inside. (Someone who speaks French could look up what Herr Doktor Guthknecht had to say in 1946 about avoiding that.)

Alan Wooff also explained that the calcium carbonate would have to be precipitated — common chalk wouldn’t do; “You wouldn’t want lumps in it.”

Perhaps (I like to give people the benefit of every possible doubt) the 14th century originators of this pious fraud did not use sausage skin — let alone Spectra/por tubing — but stripped a blood-filled vein from the saint’s leg, say, and piously washed it in a mountain stream, like kaanga pirau.

If some reaction turned the iron in the haemoglobin into FeO(OH)– a reaction with the chalky deposits of the saintly artherosclerosis, perhaps? — and all unknowing they dialysed it out, perhaps they would get the result that the faithful see in Naples to this day.


Denise of Salmond Smith Biolab (Freephone 0800-807-809) told me they could get precipitated calcium carbonate (CaCO3) from England for $22.86 a kilo, in six or eight weeks by air freight at $39. They have hydrous ferric chloride (FeCl3.6H2O) in stock at $47.22 for 250 grams. The minimum order of dialysis tubing (10mm diam, 32mm flat) is 30 metres at $60. Geoff Meadows of Clark Products Ltd quoted $36.59 for 20 l of deionised water.

The limiting dimension is the volume of the tubing, 2.35 litres. That divides into 78 samples of 30 ml each.

That’s $205.67 (plus the cost of the phials) to produce 78 phials of miraculous blood. Perhaps 20 skeptics might pay $10 each for them, so I’d be lucky to break even. That is, if all the kitchen chemistry worked out.

Of course, if I sold them outside a church at $1000 a phial…?

Anyone got access to a chemistry lab?

1. Guthknecht, R. Bull Soc. Chim. Fr. 13, 55-60 (1946)
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