Datang: Chemical Salt Production Starts, Li Er Asks for Cooperation

A doctor of chemistry is reborn in the Tang Dynasty, with only a brain and no system. Let's see how the protagonist plays with the Tang Dynasty. Purify salt, refine gunpowder, use bromide salt to control heroes, and use chemical equations to rewrite the Xuanwu Gate changes! The fight for hegemony of salt and iron hides a conspiracy, the five surnames and the seven hopes are destined to die, and Li Shimin has to call him "Sir"!