Ancient Cooling Vessel’s Secrets Unveiled

The humble ‘botijo’ harbored scientific mysteries for millennia.

A humble clay pot, the botijo, once a ubiquitous item for cooling water, harbored scientific secrets that took thousands of years and modern research to unravel. Its remarkable ability to chill without electricity has captivated scientists and curious minds alike.

A Literary Debut for a Humble Artifact

This enduring artifact was already making headlines over a century ago. In an August 1891 publication, an article titled “History of a botijo” detailed the life of one such vessel. The narrative, penned from the pot’s perspective, recounted its journey from creation to an unfortunate end, abandoned in a city landfill.

“I was born in Ocaña… There I spent my youth, in love with a casserole that, for the bright and polished, resembled a Venetian moon. Since there is no joy that lasts, one day that the heat was shown, the residents of Madrid threw themselves into the street in search of some pottery jewel that served as a bomb to put out the burning of their inflamed stomachs.”

—The Botijo, as recounted in historical archives

Global Recognition and Scientific Inquiry

The botijo’s cooling prowess was so effective that even in 1988, The New York Times sought to explain its function to its readership. The mystery of its evaporative cooling remained largely unsolved until 1990, when Gabriel Pinto, a professor at the Polytechnic University of Madrid, developed a mathematical model to decipher its science.

Unlocking the Cooling Mechanism

Pinto‘s initial experiments involved heating a botijo filled with water under controlled laboratory conditions. While his model predicted significant cooling, it fell short of explaining unlimited chilling. His university colleague, José Ignacio Zubizarreta, later refined the model by incorporating the impact of heat radiation from the air within the vessel.

Their collaborative study, published in 1995, finally provided the equations explaining the botijo’s cooling capabilities. This breakthrough illuminated a principle dating back over 5,500 years to ancient Mesopotamia, where Sumerians and Akkadians first crafted porous vessels for water preservation in arid climates.

A Timeless Tradition of Evaporative Cooling

Similar cooling containers, known as “Zeer” or “Mathi” in various Asian and African cultures, showcase this ingenious and universal solution to keeping liquids cool without artificial refrigeration. In the Mediterranean region, precursors to the botijo emerged around 2,200 BC in the Iberian Peninsula.

Archaeological findings in Murcia reveal 3,500-year-old pottery fragments with shapes anticipating the modern botijo. These early versions featured globular bodies, side handles, and a clear functional design for keeping water cool through filtration and evaporation via unvarnished clay.

Evolution and Popularization of the Botijo

Over centuries, the botijo’s design evolved, becoming more refined and widespread. Improvements in pottery during Roman and Andalusi periods enhanced its porosity and effectiveness. However, the botijo as we recognize it today, with its distinct spout and filling opening, reached its final form in the Middle Ages and gained widespread popularity by the 18th century in regions like Castilla, Aragon, and Andalusia.

The intense heatwaves experienced in Spain during the late 19th century, with temperatures soaring above 45 degrees Celsius in some southern areas, amplified the need for such cooling solutions. The botijo’s enduring practicality continued to be relevant amidst these extreme weather events.

According to the World Meteorological Organization, global average temperatures have risen significantly. In 2023, the average temperature was approximately 1.45 degrees Celsius above the pre-industrial (1850-1900) average, underscoring the ongoing relevance of efficient cooling methods, ancient or modern (WMO, 2024).

The botijo’s story, from its early literary mention to the scientific unraveling of its cooling principles, highlights a remarkable blend of cultural heritage and ingenious engineering that continues to fascinate.