30: Naples Blood

Every year on 19 September a miracle takes place in Naples Cathedral when Saint Januarius’ blood is held up by the resident bishop. The 1,600 year old blood liquefies and the Neapolitans can breathe a sigh of relief for another year.

Professor Garlaschelli, a chemist at the University of Pavia has come up with another theory: the `blood’ is a thixotropic gel. Despite not being able to analyse the holy relic, Professor Garlaschelli has created a remarkably similar substance using the ingredients given here.

What you will need

weighing balance
150cm3 - 250cm3 beakers
iron(lll) chloride, hydrate
sodium chloride
eye protection 		dialysis tubing
100cm3 measuring cylinder
calcium carbonate powder

What you do

  1. Eye ProtectionIrritant
    Mix 10g iron(III) chloride hydrate with 20g calcium carbonate powder in about 100cm3 of water. A deep red suspension is formed.
  2. Pour this suspension into a suitable length of dialysis tubing. Close the tubing with a clip or knot and place it in a beaker of distilled water for about four days.
  3. After four days pour the contents of the tubing into a clean beaker.
  4. Add 1.5g of sodium chloride to the suspension taken from the dialysis tubing.
    A thixotropic gel which has a similar consistency to tomato ketchup should form in about one hour.
  5. Gentle shaking will cause the gel to liquefy and if you leave it to stand it will re-solidify.
Eye Protection
eye protection must be worn

Irritant
IRRITANT
iron chloride solid and solution

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