Bizarre Plots to Bezoars Stones: Poisons and Antidotes in Medici Florence

Claire Litt //

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Figure 1: Spherical bezoar stones from unknown animal, 1551-1750.  Science Museum, London. CC BY

On February 8th, 1548 a ciphered letter addressed to Duke Cosimo I reported that “The Farnesi every day try new practices to kill Don Ferrando [Gonzaga] with poison” (Medici Archive Project Doc ID# 5407). By the mid-16th century in Italy, the brazen daylight attacks that characterized assassinations of political leaders in previous centuries were increasingly replaced by more surreptitious methods, often using arsenic or other poisons (Barker, 72). Grand Duke Cosimo I de’Medici, in the wake of the gruesome homicide of his predecessor Alessandro de’Medici in 1537, instigated a manhunt for the perpetrator, Lorenzaccio (“Bad Lorenzo”) de’Medici. Eleven years later, Lorenzaccio was assassinated in Venice by a Florentine agent. Cosimo I was not, however, so naïve as to think that making an example of Lorenzaccio would put off other would-be assassins, especially since they could conceal their identities by slipping something into his food. The Grand Duke instead determined to find antidotes to combat the new alchemical-style of assassinations. While Alessandro’s death was officially the end of the main branch of the Medici tree, Cosimo I’s ancestry made him the link between the main and popolani (popular) branches. It was his popolani heritage, and specifically his inheritance of medical recipes from his grandmother Caterina Sforza, that helped him create antidotes to poisons and establish a strong tradition of alchemical experimentation in the Grand Ducal family.

Cosimo I was the great-great-grandson of Lorenzo il Magnifico, de facto ruler of Florence, through his mother, Maria Salviati. It was his paternal grandmother however, Caterina Sforza, who initiated a traceable genealogy of scientific experimentation (Ray, 10). Caterina created medicinal and cosmetic recipes and recorded them in a book, Gli Experimenti de la S.r Caterina da Furlj Matre de lo S.r Giouanni de Medici (The Experiments of the Most Excellent and Serene Caterina of Forli, Mother of the Most Illustrious Signore Giovanni de’Medici). This book, written in the fifteenth century, was passed to her son Giovanni and then to Cosimo I himself. Cosimo I’s correspondence indicates that he used trusted recipes, likely ones he inherited from his grandmother, as well as new experimental concoctions. On November 16th 1547, his friend Ferrando Gonzaga requested “remedio contro il veneno”, a remedy against poison (MAP Doc ID #23268). While Cosimo I sent him “cruets of oil”, antidotes without any warnings attached, another vile of antidote that Cosimo I sent Ferrante in January 1548 bore the warning that he should test it on a prisoner who was “already destined for death”(MAP Doc ID# 7450). This cautionary advisory gives the impression that the antidote was not a tried-and-true recipe from Caterina’s book, but rather a substance of his own invention. Curiously, Caterina claims that one of the recipes in her book came from Cosimo il Vecchio, the patriarch of the main branch of the Medici family (Ray, 15). This link would make both Cosimo I and his recipe book the physical manifestations of Medici reunification – the consolidation of genealogy and cumulation of intergenerational scientific knowledge.

In 1569, at the age of fifty and after thirty-two years of avoiding assassination, Cosimo I became one of the few early modern leaders to voluntarily retire. His son Francesco I de’Medici carried on Cosimo I’s strong interests in alchemical experimentation. Until recently, it was suggested that Francesco I and his wife Bianca Cappellos’ deaths on October 19 1587 were the result of their exposure to toxic substances from their alchemical laboratory. A toxicology carried out on their remains in 2006 indicates that both were exposed to high levels of arsenic in a short time period. This evidence vindicates contemporary rumours that the couple were intentionally poisoned. Some scholars point to Cardinal Ferdinand, Francesco I’s younger brother who was vacationing with the ducal couple at their villa in Poggio a Caiano at the time of their deaths, as a suspect for their murders. After the death of his legitimate male heir, Francesco I attempted to legitimize his son Don Antonio, who was born out of wedlock to Bianca Cappello while Francesco I was still married to Joanne of Austria. It is possible that his brother the Cardinal did not support this plan, and chose instead to murder Francesco I and his wife. After his brother’s death Ferdinand I denounced his cardinalship and became Grand Duke in 1588. A year later, Ferdinand I sent poison with a letter to an accomplice of his for the purpose of assassinating an unknown opponent. In the letter he described the poison as having “[…] no smell, no taste, and operates powerfully […]”, which indicates that the poison was arsenic. The Grand Duke offered to pay “three thousand crowns and also 4 to those who will give him the poison […]”(MAP Doc ID# 12397). Evidence of Ferdinand I’s murderous scheming, using the same poison that his brother died of and only a short time after his death, is a condemning indication of the former Cardinal’s fall from grace.

Given his familiarity with poisons, Ferdinand I’s interest in securing reliable antidotes is unsurprising. While he continued to make antidotal oils, such as his grandmother Caterina invented, he also became interested in bezoar stones, which had incredible popularity in the courts of 16th and 17th-century Europe [Figure 1]. The bezoar stone’s name originates from the Persian word padzahr, from pâd-, meaning to expel and zahr- , meaning poison (Do Sameiro Barroso, “The Bezoar Stone”, 375). Bezoar stones were concretionary secretions made of indigestible materials usually found in the stomaches of hoofed animals (Manutchehr-Danai, 112). Some sources claimed that these stones came from the stomaches of unicorns. The stones, which were often embedded into jewellery and worn, would be powdered and dissolved into liquid as a remedy for arsenic poisoning. Most bezoar stones were imported from the East, usually from Goa, or from the New World. In June 1608, Ferdinand I’s niece Eleonora de’Medici-Gonzaga, the daughter Francesco I, wrote to him to thank him for a “pietra di porcospino”, a special kind of bezoar stone used in Chinese medicine (MAP Doc ID# 5099; Millones Figueroa, 152). In 1998, a study carried out on bezoar stones proved their efficacy for removing both the arsenate and arsenite compounds of arsenic from a solution. Bezoar stones are comprised of both the mineral brushite and degraded hair. Brushite is the analogous phosphate chemical formula, CaHPO4·2(H2O), to arsenate pharmacolite, CaHAsO4·2(H2O). Arsenite binds with sulphur compounds found in proteins of degraded hair. Together they effectively neutralizing the effects of the arsenic (Do Sameiro Barroso, “Bezoar Stones, Magic, Science and Art”, 389). Ferdinand I could not have known the modern scientific reasoning behind why these stones worked. Instead, bezoar stones are an example of ‘rational magic’  – an instance in which the effectiveness of the outcome gave credence to its mythological origin. Ferdinand I’s use of them demonstrates the persistence of the intertwined nature of magic and science into the 17th century.

 In 1593, a Florentine apothecary name Stefano Rosselli wrote down all his “secrets” in a book for his sons. One of his recipes is entitled “How to make oil to counteract poisons, from the Grand Duke of Tuscany Cosimo de’Medici” (Zayas, 117; Barker, 78). Even though the Medici clearly sought to conserve their recipes and ingredients amongst themselves and their allies, their experiments were inevitably disseminated among apothecaries such as Rosselli. Without drawing a straight line of progression between their experiments and the origins of pharmacological research, the Medici undoubtably increased their collective understanding of natural philosophy and chemistry as knowledge was passed down and compounded by each generation’s trial-and-errors. At the same time, this increased body of knowledge continued to include magic even after the Scientific Revolution in the 17th century. More importantly, the Medici’s work should be viewed as a response to their desire to avoid alchemical assassination and to poison their enemies, who, we can speculate, may even have been amongst themselves. This serves as a reminder of the historical contingency of scientific research where the social world shaped alchemists’ inquiries – just as it continues to shape scientists’ questions today.

Works Cited:

Spherical bezoar stone from unknown animal, 1551-1750. Credit: Science Museum, LondonCC BY

Primary Sources:

BIA: The Medici Archive Project, Doc ID # 12397 (Archivio di Stato di Firenze, Mediceo del Principato 3121a, folio 22, not numbered transcribe folio) July 25th 1590, Ferdinando I de’Medici to Modesti, Giovan Vincenzo (Cavaliere).

BIA: The Medici Archive Project, Doc ID# 11840 (Archivio di Stato di Firenze, Mediceo del Principato 3101a , folio 1006 , not numbered transcribe folio).

BIA: The Medici Archive Project, Doc ID # 23268 (Archivio di Stato di Firenze, Mediceo del Principato 3191a, folio 886, not numbered transcribe folio) November 16th, 1547.

BIA: The Medici Archive Project, Doc ID# 5099 (Archivio di Stato di Firenze, Mediceo del Principato 2944 , folio 530 , not numbered transcribe folio). June 20 1608. Eleonora de’Medici-Gonzaga to Ferdinando I de’Medici.

Secondary Sources:

Barker, Sheila. “Poisons and the Prince: Toxicology and Statecraft at the Medici Grand Ducal Court,” in Toxicology in the Middle Ages and Renaissance. pp. 71-82, Ed. Philip Wexler. London, UK, Elsevier Academic Press: 2017. 

Do Sameiro Barroso, Maria. “Bezoar Stones, Magic Science and Art.”

Mari, Francesco, Aldo Polettini, Donatella Lippi, and Elisabetta Bertol. “The Mysterious Death of Francesco I De’ Medici and Bianca Cappello: An Arsenic Murder?” BMJ: British Medical Journal 333, no. 7582 (2006): 1299-301.

Millones Figueroa, Luis. “The Bezoar Stone: a Natural Wonder in the New World.” Hispanofila, vol. 171, June 2014, pp. 139–156. Academic Search Complete, EBSCOhost, doi:10.1353/hsf.2014.0028. Accessed 26 Mar. 2019.

Ray, Meredith K. 2015. Daughters of Alchemy: women and scientific culture in early modern Italy. Cambridge, Mass. : Harvard University Press.

Rosselli, Stefano. Mes secrets à Florence au temps des Médicis 1593. Édition établie par Rodrigo de Zayas.

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