In the 6th century B.C. , the ancient Chinese were the first people to use cast iron for tools, weapons, and cooking pots. It was a long process to make the cast iron. Therefore, in the first century A.D. , a blast furnace was invented by an unknown person. The blast furnace was powered by steam and boiling water. The furnace shot out hot air which heated the iron.
Heated iron is much easier to work with.
This early furnace might have opened the way for the creation of steel. The ancient Chinese loved to drink tea. Drinking tea became very popular during the Tang Dynasty. At first, tea leaves had to be chopped or shredded by hand which was very time-consuming. A Chinese inventor created the tea shredder.