Scholars Propose New Interpretation of Ancient Chinese Bell Metal

A new study in the journal Antiquity, “The Six Recipes of Zhou: A New Perspective on Jin and Xi,” written by A.M. Pollard and Ruiliang Liu and published by Cambridge University Press, suggests a composition of ancient Chinese bronze that has puzzled archeologists, metallurgists, and linguists for decades.

Roughly 2,300 years ago during the Zhou Dynasty, in a region just north of the modern metropolis of Shanghai, ancient scribes recorded six formulae, or recipes, for casting different types of bronze for specific objects. Generally thought to have been written between the fifth and third centuries BCE, the Rites of Zhou distinguishes these recipes based on the proportions of two components: Jin and Xi.

A translation of the text provided by the researchers presents the recipes as follows: The jin is divided into six, tin occupies one. This is the receipt (recipe) for bells and tripod-vessels. The jin is divided into five, tin occupies one. This is the receipt for axes and hatchets…and so on.

What are Jin and Xi? That is precisely the question researches have been looking to answer. Even with sustained scholarly analysis for the last 100 years, an interpretation of Jin and Xi has eluded explanation. While conventionally interpreted as copper and tin, respectively, the latest research proposes that Jin and Xi may themselves be alloys (a metal made by combining two or more metallic elements).

Bronze Age heads from the UNESCO-listed Sanxingdui archeological site in China

Image: Bronze Age figures of heads from the UNESCO-listed Sanxingdui archeological site in modern Guanghan, Sichuan, China.

You’ll remember that bronze is an alloy of roughly 80% copper to 20% tin. This 4:1 ratio comes together in a crystal lattice arrangement of atoms within the alloy, creating a harmonious damping capacity (the bronze’s ability to absorb energy) and sound velocity, which is what makes the toll of a bell (and related instruments, like cymbals) ripple across a neighborhood.

The new paper suggests that, rather than working with raw materials like pure copper and tin, artisans creating coinage, instruments (bells and gongs), armor, weaponry, and sculpture plausibly worked with ingots of pre-made alloys: Jin being a leaded bronze and Xi being a copper-lead alloy. How was that conclusion reached? Review the methodology and read the researchers’ interpretation of the data. 

Perhaps the mystery behind the earliest textual record of metallurgy in East Asia has been solved. This new theory suggests that mass bronze production in ancient China was far more complex than scholars had supposed – helping us understand the importance ancient civilizations placed on bronze objects like bells.

Cover image: The Bianzhong of Marquis Yi of Zeng, an ancient musical instrument comprising 64 bronze bells, cast in 433 BCE, on permanent display at the Hubei Provincial Museum in Wuhan, China.