Duzhong, also known as Sixian, Chesipi, and Silianpi, is mentioned in the "Shennong's Materia Medica". It is the dried bark of the Eucommia ulmoides Oliv., a plant in the Eucommiaceae family. The bark is harvested from April to June, and the rough outer bark is scraped off. The inner bark is then piled up and "sweated" until it turns purplish-brown, and finally dried in the sun.
[Processing Method] 1. Duzhong "Leigong Paozhi Lun": "Before use, the rough outer bark must be shaved off... Use a fine file." "Newly Revised Materia Medica": "Thinly shave off the upper bark, cut horizontally to break the fibers." Currently, the raw herb is taken, residual rough bark is scraped off, washed, and cut into fibers or pieces, and then dried.
2. Salt-processed Duzhong "Wanshi Nüke": "Stir-fry with salt water to remove the fibers." "Complete Book of Ulcers": "Stir-fry with salt to remove the fibers, and grind into powder." "Youyou Jicheng": "Cut into slices, stir-fry with salt water until the fibers break." "Newly Expanded Collection of Tested Recipes": "Cut into slices, soak in salt water for seven days, changing the water daily, stir-fry with low heat in a copper pot until the fibers break." Currently, Duzhong fibers or pieces are mixed with salt water, thoroughly moistened, placed in a pot, heated over medium heat, stir-fried or scalded until the fibers easily break, and then taken out and cooled. For every 100kg of Duzhong fibers or pieces, 2kg of table salt is used. Alternatively, Duzhong fibers or pieces are mixed with salt water, thoroughly moistened, placed in a pot, heated over medium heat, stir-fried or scalded until the fibers easily break, and then taken out and cooled. For every 100kg of Duzhong fibers or pieces, 2kg of table salt is used. Or Duzhong fibers or pieces are moistened with salt water, left overnight, steamed for 1 hour, taken out, and dried. For every 100kg of Duzhong fibers or pieces, 0.9kg of table salt is used.
