2. Purple bamboo salt, that is, natural sea-floor salt is put into a bamboo bucket which has grown and developed for more than 3 years, and both sides are sealed with loess layers less than 4 meters in the deep forest. Then, the bamboo bucket filled with bamboo salt is put into a specially made furnace, and the special direction is selected, and the turpentine oil is sprayed, and red pine is used at 1000~ 1500℃.