"The Secret of Immortal Health Care" records: "A catty of mercury, a catty of black tin, and a catty of mountain ze. Black tin is boxed, and Yamazawa is boxed. The Yamazawa box is filled with mercury first, which is airtight. The tin box contains a silver box, and the silver box is placed in an iron tripod. The inside (used) halloysitum rubrum and raw honey are used to fix the tripod mouth. Tie it up and down with iron wire and enter the quiet room of Dan room, using 250 kilograms of charcoal. When it catches fire, it will come out in the morning. Open the tripod, but I can't see black tin and mercury. It is a secret to use two kilograms of Yamazawa at will. (For the secret of the immortal's health preservation, see Taoist Collection, Volume 593) The first three "Shanze" in this paper are natural silver, and the last "Shanze" is medicinal silver, namely lead amalgam, which contains some silver. (Hua, Zhang Huizhen: Textual Research and Simulation Experimental Research on Gold and Silver in Ancient China Elixir, No.2 Research on the History of Natural Science, Vol.6, 1987, pp. 105~ 122).