After over a century of scrutiny, researchers now claim they have identified the two secret ingredients in China’s ancient recipes for bronze forging.

Since 1920, scholars have been scratching their heads over the meaning of Jin and Xi, two mysterious components that appeared in the Kaogong Ji. 

Kaogong Ji is Chinese literature from 300 BC, which contains six formulas for forging bronze, one of the most valuable items in the Zhou Dynasty (1050–221 BCE). It was written in the region that has become the north of modern-day Shanghai.

In a study published in the journal Antiquity on August 10, the researchers believed they may have determined the possible meaning of Xi and Jin by looking at the metal ratio in coins from the Zhou era.

The coins were made of two pre-prepared alloys, one copper-tin-lead, and one copper-lead. This has led them to suspect that Jin and Xi could have been names of premixed metals or metal alloys.

As the Guardian cited, Professor Mark Pollard from the University of Oxford said, “When you consider the possibility that ancient artisans were using pre-prepared alloys, you get a composition which looks like genuine early Chinese bronzes…. It suddenly struck me that if you reinterpret what Jin and Xi mean, they probably describe pre-prepared alloys.”

Ruiliang Liu, the lead author and curator of the early China collection at the British Museum, told Inverse that the new study indicates that bronze manufacture may have been more complicated than previously thought.

Pollard said, “It implies a whole new stage of metal preparation and supply that we didn’t really know about.”

Still, the researchers believe what was written in the Kaogong Ji document may not fully stand for the genuine art used at the time.

Pollard says, “The existence of this text suggests there was some imperial control of the production of bronze. … It’s a sort of administrative fiction. The sheer scale of what was going on means that we think nobody was truly in control.” 

However, Liu views that the discovery offers valuable new insights into the beginnings of Chinese bronze. He added that there is still a great deal to uncover about Jin and Xi.

Liu stated, “This is the nature of research. An iterative process with old questions resolved but new questions are emerging.”

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