Eugène Canseliet once wrote that Pierre Curie in all his researches from magnetism to piezoelectricity and radioactivity was actually chasing the Philosophers Stone.

Pierre Curie photographed by Dujardin c1906Canseliet  witnessed the friendship between Fulcanelli and Pierre Curie. And that is not surprising: both attended the same esoteric milieux, which fact Curie never denied, but actually wrote to his fiancée Maria Skłodowska, in 1894: “I must admit that those spiritual phenomena intensely interest me. I think in them are questions that deal with physics”. By the way, Canseliet told us that J.J. Champagne too used to attend Curie’s home.

In l’Alchimie Expliquée sur ses  Textes Classiques Canseliet wrote: “Like the unlucky discoverer of radium (Pierre Curie), Fulcanelli knew very well that the fire under his oven, or burners, was unable to produce any transmutation. The sublimity of the arcane awoke his caution in revealing, so, when covering the Secret Fire topic, he never went beyond the ancient alchemists. This is also the reason why we have treated once again on the chemical and physical realization by this great unknown. Fulcanelli met Pierre Curie, and then Madame Curie, born Maria Skłodowska who, according to him, neither was a true Perrenelle, nor the devoted companion of the Mutus Liber plates. But this is not our subject: what is usually ignored is that Curie, into the rare earths, was looking for the Philosophers Stone”.

Canseliet went on to reveal that the entire Curie family’s researches were targeting to find out the properties of metals leading to the Alchemy’s final goal. Pierre Curie showed that the magnetic properties of a given substance change at a certain temperature. This temperature is now known as the Curie point. The discovery of the Curie point, freed from the critical temperature, above which the ferromagnetic bodies change their state to paramagnetic, sufficiently indicates the alchemical orientation of Pierre Curie’s work.  Fulcanelli was convinced that there was a way  known as Ars Brevis much faster than the classic dry metallurgic process, and this might lay in some unknown properties of some minerals. While the Curies were probably more interested in deepening the scientific aspects.

The chapter in the end of his l’Alchimie Expliquée sur ses Textes Classiques, in which Canseliet inserted his observation about Curie’s researches, was dedicated, and entitled, to the Last Cooking (see the Opus Magnum scheme. The following grand final to this chapter will be the appendix with the description of the Philosophic Egg, emitting the weird musical whistles, which the readers may have already read about (see my article Canseliet, the Art of Music & Weight) (1).

To confirm his general purpose, Canseliet’s pointed soon at the high degree of heat reached in the Last Cooking, and specifically at what would happen to the chemical-physical properties of matter in order to be able to define the whole process as “alchemical”, and not mere chemical, i.e “magical”, or unexpected. Which, with Curie, he would have defined as “magnetic”. Canseliet said: “we know very well that the heat supplied in the Last Cooking cannot alone perform the miracle we hope to see. There must certainly intervene something highly magical, embodied in the allegory of the cat, who can see and hear through his whiskers“.  Like Perrault’s fairy tale, where a cat ( not common, but with riding boots, so a cabalist little feline) saves his master (the Marquis of Carabas, that’s to say the low-grade gold) from poverty and misfortune. Alchemically, the cat with riding boots can procure wealth. Or rather, the cat’s whiskers. That’s to say, according to Canseliet’s theories, the electromagnetic waves, which he, together with Curie and Fulcanelli, conceived only in their magnetic side.

pierre curie doctoral these on magnetismNot surprisingly Curie, together with his brother Jacques, while coming to torment the matter taking a hammer and pressing it, was primarily interested in understanding what was magnetically going strange inside the structure of a material subjected to high degree of heat. In fact it is known that the starting point of Curie’s theories was the study of magnetism, as he demonstrated in his famous PhD thesis. Almost a century after, we are instead used to interpret Pierre Curie’s discovering on the heated and stressed material mostly pointing at piezoelectric aspects. Or polarized. At least electric. But, of course, it is certainly true that the ferromagnetic materials heated by Curie at a critical heating degree ceased to be ferromagnetic. And that, for Curie, was the utmost discovery.  In fact, he showed that the magnetic properties of a given substance change at a certain temperature. This temperature is now known as the Curie point.

But let’s proceed in order. Pierre moved on to investigating magnetism, uncovering an intriguing effect of temperature on paramagnetism now known as Curie’s law. Another discovery was the above mentioned Curie point: the critical temperature at which ferromagnetic materials cease to be ferromagnetic.

jacques and pierre curieGoing on with their researches, the brothers Curie thought there would be a direct correlation between the potential generated by temperature changes and the mechanical strain that gave rise to piezoelectricity. They expected that a piezoelectric effect would arise in materials with certain crystal asymmetries. Armed with the crudest of materials — tinfoil, glue, wire, magnets, and a simple jeweler’s saw — they tested various types of crystals, including quartz, topaz, cane sugar, Rochelle salt, and tourmaline. As a result, the Curies found that when such materials were compressed, the mechanical strain did indeed result in an electric potential. The strongest piezoelectric effects were found in quartz and Rochelle salt. The brothers put their discovery immediately to good use by inventing the piezoelectric quartz electrometer. “In 1880, Jacques and Pierre Curie (photo left) discovered an unusual characteristic of certain crystalline piezo electric crystals with electrodes: when subjected to a mechanical force, the crystals became electrically polarized. Tension and compression generated voltages of opposite polarity, and in proportion to the applied force. Subsequently, the converse of this relationship was confirmed: if one of these voltage-generating crystals was exposed to an electric field it lengthened or shortened according to the polarity of the field, and in proportion to the strength of the field. These behaviors were labelled the piezoelectric effect and the inverse piezoelectric effect, respectively, from the Greek word piezein, meaning to press or squeeze.

The Curie brothers did not, however, predict that crystals exhibiting the direct piezoelectric effect (electricity from applied stress) would also exhibit the converse piezoelectric effect (stress in response to applied electric field). This property was mathematically deduced from fundamental thermodynamic principles by Lippmann in 1881. The Curies immediately confirmed the existence of the “converse effect,” and continued on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals.

There was another twist to the piezoelectric saga still to come. The following year, mathematician Gabriel Lippman demonstrated that there should be a converse piezoelectric effect, whereby applying an electric field to a crystal should cause that material to deform in response. The brothers rushed to test Lippman’s theory, and their experiments showed the mathematician was correct. Piezoelectricity could indeed work in the other direction.

After the initial flurry of excitement died down, piezoelectric research faded into the background for the next 30 years or so, in part because the theory was so mathematically complex. But incremental progress was still being made. In 1910, Woldemar Voigt published the definitive treatise on the subject, Lehrbuch der Kristallphysik, a massive tome describing the 20-odd classes of natural crystal with piezoelectric properties. More importantly, it rigorously defined the 18 possible macroscopic piezoelectric coefficients in crystal solids.

This set the stage for subsequent development of practical applications for such materials, beginning with sonar in 1917, when Paul Langevin developed an ultrasonic transducer for use on submarines using thin quartz crystals. Many automobiles today have ultrasonic transducers to assist drivers in measuring the distance between the rear bumper and any obstacles in its path.

In conclusion, Curie’s brothers discovery was about converting Mechanical Vibration into Electricity. The present state of piezoelectric technology is today about some fine ceramics (also known as “advanced ceramics”) possessing a unique property which allow them to convert mechanical shock or vibration into electrical signals, and vice versa. These materials are called piezoelectric ceramics.

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