Little known.
In ancient Huaxia, the purification of salt had always been a troublesome affair.
In the most primitive tribal eras, humans initially relied on eating raw flesh and blood to obtain salt.
After entering the era of civilization,
the ancestors found salt wells and thus gained methods for processing crude salt.
By the Tang and Song periods, fine salt refined from sea salt gradually appeared and was quite expensive.
The highest price even reached a pound... or rather sixteen taels and ninety wen.
But the term 'fine salt' here is actually a concept compared to earlier crude salt.
Compared to the standard table salt of later generations, the fine salt of this period still contained many impurities.
Such as sulfate ions, magnesium ions, calcium ions, etc...
Especially magnesium ions.
This stuff, when entering the human body, could cause diarrhea, heart function disorders, and other anomalies.
