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The Yin refining method uses urine from prepubertal boys (tongbian), the quantity being unrestricted. For every shi (a unit of volume) of urine, one large vat is used for storage. One shi of clear water is mixed in with it. One cup of decoction prepared from Gleditsia Sinensis Fruit (Zaojiao, 皂荚) is added, and the mixture is stirred hundreds of times with a bamboo rod until stopped. After waiting for it to settle and clarify for a moment, the upper clear portion (one shi) is poured out. Another shi of clean water is added, and it is stirred as before. The process of clarifying and pouring is repeated; the precipitate gradually becomes thicker with each cycle. This continues until after ten cycles, the substance condenses like frost or snow, at which point the water is removed. It is dried on cloth spread with paper ash, collected, and the Qiushi (Autumn Stone) is sun-dried and ground again. Alternatively, male breast milk can be added to blend it. It is exposed to the sun during the day and dew at night for seven cycles of seven days (49 days), after which it can be used as either a powder or pills. Taking it for one year can extend life by one jiyi (12 years). This is the Yin refining method. Although the salty taste is washed away, the essential nature of the material is depleted. As mentioned, the primordial qi is mixed and leaked; while it certainly retains the function of resolving phlegm and descending fire, it cannot act as rapidly as when the salty taste is retained. Its tonifying efficacy can be discussed similarly. Nowadays, people often debate its superiority or inferiority, so I have distinguished between Yin and Yang methods.

The Yang refining method requires preparing several new vats. More than ten shi of urine from prepubertal boys are collected. The collection method involves stationing a person to guard the medicine vats in a school for young students. A small vat is placed beside the medicine vat. When students urinate, their urine color is tested first; only clear, reddish urine is taken. Urine that appears red due to pathogenic heat mixing in is discarded and not used. Only clear, white urine is collected. Once ten shi are accumulated, they are moved to a secluded place and boiled in a large pot. More urine is added as it evaporates, until all ten shi are completely dry. The residue, which resembles iron or stone, is called "Pi Tai" (丕胎). This Pi Tai is placed in an earthen crucible and heated over a bright fire until black smoke and foul odors are completely eliminated; this stage is called "Tui Yin Fu" (Retreating Yin Talisman). It is then taken out and boiled in a small silver pot with freshly drawn spring water (if no silver pot is available, a copper pot may be used). It melts into a formless state, is filtered, and the pure liquid drips down like clear spring water. It is returned to the silver pot and boiled dry, resulting in a substance as white as snow, clean and lustrous without dust. Milk or Hongqian San (Red Lead Powder) can be freely added, and pill forms are suitable for consumption. If this snow-white medicine is placed in a cinnabar furnace and refined over a bright fire, it dissolves clearly with rosy light, and through smoldering earth, it forms a spiritual elixir resembling jade. From this, it can be seen that the treasures within the human body are indeed genuine; how could those who consume it fail to experience efficacy!