Simplify the following text for a Grade 8 native English-speaking person.
Original: One of China 's emperors , QÃ n ShÇ HuÃ ng DÃ â '' allegedly buried in a tomb that contained rivers of flowing mercury on a model of the land he ruled , representative of the rivers of China â '' was killed by drinking a mercury and powdered jade mixture ( causing liver failure , poisoning , and brain death ) intended to give him eternal life .
Simplified: One of China 's emperors , QÃ n ShÇ HuÃ ng DÃ , is said to have been buried in a tomb with rivers of flowing mercury . He was killed by drinking a mixture of mercury and powdered jade because he wanted to live forever .