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*Bo Wu Zhi* (Records of Various Things) and Tao Hongjing both state that these two types of stones are taken by storks to cover their eggs; if this is the case, then they are the same substance. Hongjing further states: If the Immortal Scriptures do not refer to it as "Te Sheng" (Specially Grown), then it is merely the aforementioned White Stone (Bai Shi). The current *Bu Zhu* (Supplementary Annotations) merely interprets the text literally, failing to grasp the meaning of "Te Sheng." Essentially, these two records refer to the same substance, differing only in whether it is "Te Sheng" or not. What is meant by "Te Sheng" is that it grows independently, not adhering to other stones. Currently, its use in medicine is extremely rare; only Dai Zhe Shi (Hematitum, 代赭石) is used, but it must be employed with extreme caution due to its severe toxicity. Regarding the stone found in stork nests, the claim follows erroneous theories. There is no such stone in stork nests; yet it is said: Storks frequently enter water and become cold, so they take it to cover eggs for warmth. If this were true, then cormorants, geese, and similar birds, which also feed in water, would naturally reproduce and thrive without needing these two stones. Their arguments often adopt the words of laymen, never investigating the actual situation or exhausting the principles involved. I once served as an official in Shun'an Jun and personally inspected stork nests, finding almost no stones. Moreover, how could stones be present everywhere? However, it is effective in treating long-standing accumulations and chronic coldness in the chest and abdomen, but must be used cautiously because its toxicity is formidable.

It is widely used in the furnace fires of alchemists. Those with a nail-head luster, solid texture, and reddish-purple color are considered superior.

Bai E (Chalk) is white fertile soil, known in the capital as Bai Tu Zi (White Earth Child). Cut into pieces about one square inch in size, sold in the market, people use it to wash clothes. Nowadays, people mix equal parts of Wang Gua (Trichosanthes Cucumerina Fruit) and Bai E, grind them into powder, and take two qian with hot water to treat headache.

Chi Tu (Red Earth) is currently used by public offices to decorate rafters and pillars. Mixed with water into a fine powder, taking one or two qian treats wind-rash.

New salt is not bitter; after a long time, it becomes salty and bitter. The salt produced in the Jiezhou Salt Pool now forms clods of varying sizes and shapes, and becomes bitter over time. Salt boiled from seawater has a milder taste; the two salts have their respective advantages and disadvantages. For medicinal use and silver/gold crafting, Da Yan (Large Salt) and Jie Yan (Jiezhou Salt) are mostly used. People living near the sea often have dark skin, likely due to daily consumption of fish and salt, which is evidence of salt entering the blood vessels. When blood oozes from the gum spaces, rinsing with salt water helps, and salt guides medicines into the Kidney Meridian. Northern barbarians use salt to pickle corpses to prevent decay.