Library

Lei Gong said: Longgu (Fossilized Bones, *Longgu*) produced in Shanzhou, as well as those from Cangzhou and Taiyuan, are of the highest quality. Those with fine bone texture and broad patterns are female; those with coarse bone texture and narrow patterns are male.
Those with five-colored bones are superior; white ones are medium grade; black ones are inferior; yellow ones are barely acceptable. Do not use those found in unclean places or those collected by women.
When preparing it, first wash it twice by bathing in a decoction made from aromatic herbs. Then crush and grind it into powder, and store the powder in a silk bag. Take one swallow, split open its abdomen, remove the entrails, place the bag containing the bone powder inside the swallow's belly, and hang it above a well overnight. At dawn, remove the swallow and the bag, and grind the bone powder ten thousand times more; its efficacy is miraculous.
However, when taken by men, it should be consumed on an empty stomach. It is placed within kidney-nourishing formulas to facilitate the Qi of Longgu entering the Kidney organ.

Lei Gong said: In practice, there are many counterfeit products; it is better not to use them at all. Musk (*Shexiang*, *Moschus*) is divided into three grades: The first is called "Yi Xiang" (Lost Fragrance), which occurs when the musk deer's scent sac is full and closed. The deer rubs its sac against a stone until it bursts with its hoof tip; where the substance falls, no grass or trees grow for a li, and the substance turns scorched yellow. If obtained, this fragrance is worth as much as a bright pearl. The second is called "Xi Xiang" (Knee Fragrance), which is harvested and very suitable for use. The third is called "Xin Jie Xiang" (Heart-Knot Fragrance), which results when a large beast startles the deer, breaking its heart. The deer runs madly, mixes with other herds, and eventually jumps into water, where it is retrieved by humans. Upon splitting open, blood flows from the heart and accumulates on the spleen, forming a large dry blood clot. This fragrance can be smelled across a mountain stream and is considered the lowest grade among musks.
When using Shexiang, it should be opened on Zi days. It should not be ground too finely; simply grind and sieve it for use.

Lei Gong said: There are four types of Niuhuang (Calculus Bovis, *Niuhuang*): The first is "Sheng Shen Huang" (Living Divine Yellow), obtained through deception. The second is "Jiao Huang" (Horn Yellow), extracted directly from the horn. The third is "Xin Huang" (Heart Yellow), identified and removed by experts after the ox dies of illness; upon splitting the heart, the calculus is found inside, resembling thick yellow sauce. Immediately after collection, it is thrown into water, where it hardens like crushed Tribulus seeds or beans, becoming as hard as imperial pearls. The fourth is "Gan Huang" (Liver Yellow); the ox has a glossy body, reddish eyes, enjoys playing with water, reflects light, possesses night-glowing properties, and fears humans. Alternatively, if collected separately, it may possess miraculous properties.
When using Niuhuang, it must first be individually pounded and ground finely like dust. Wrap it in silk, then wrap that in fresh yellow cowhide. Place it above a well, about three to four feet above the water surface, and leave it overnight until morning before use.