In the Cathedral of Naples An ampoule is kept that should contain the Blood of San Gennarothe patron of the city. During some anniversaries, such as the feast of the saint who celebrates the September 19ththe blood could “melt” or more correctly liquefythen pass from liquid “coagulated”. According to tradition if this happens we speak of prodigy or “miracle“And of a good omen event for the city and the inhabitants, while the lack of liquefaction is an unfavorable sign. There is a plausible scientific explanation for why it melts? From the chemical point of view, some hypotheses have been advanced to explain the phenomenon: one concerns a substance with a low melting point while another the presence of a thissotropic mixture.
To find out what happens with certainty, it should be withdraw a little of this liquid, analyze it with current modern instrumentation and obtain information on his chemical composition. However, since the Catholic Church has never given permission to scientists to open the ampoule, for now nobody can really know what’s inside. In fact, the “analysis” were carried out, one of the 1902 and one in 1989but only by studying the light coming from the liquid, without opening the ampoule. Furthermore, these studies are not never been published in a magazine and consequently have not been validated from the scientific community.
However, there are two hypotheses on the content:
- The first is that it contains a substance that has a low melting point. So the temperaturefor example through the warmth of the hands, the mergerthe passage of state Solid to liquid.
- The second hypothesis is that it contains one Tissotropic mixture. That is, a substance that is solid if it remains firmbut that if it comes agitated becomes liquid And it returns solid if it is left firm again.
The interesting thing to support this last theory is a study published in 1991 on Natureone of the most prestigious and influential scientific journals in the world. In this study, three researchers from Cicap (Italian Committee for the control of statements on pseudosciences) have recreated a mixture using some substances and techniques that were available in 14th centurywhen the first liquefaction occurred the August 17, 1389.
Scientists mixed ferric chloride (Fecl3), a salt also present on the slopes of Vesuvius, e calcium carbonate (Caco₃), the limestone. This mixture was then left in soaking in the water inside a piece of parchment and at the end of the Municipality of the Municipality kitchen salt (NACL). One was thus obtained red substance With tissotropic properties, therefore initially solid, but which became liquid by shaking it.
This study shows that technically in the Middle Ages such a substance could be produced, but it is good to reiterate that it is only a hypothesis and that until the ampoule is opened we will never be able to know with certainty what it contains.
At this point the question can arise spontaneously: how the times the blood are explained does not melt? According to the first hypothesis, a plausible response would be that the temperature does not reach high enough values to be able to merge the mixture. While in the event that there was a thissotropic mixture, the ampoule may not have been agitated with sufficient energy and that therefore the substance could not show its ability to change the state of solid to liquid.
In any case, you live or Sang and San Gennar!
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