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Method for Preparing Alum and Nitre. Also known as Jade Elixir (Yudan) or Snow Frost (Xueshuang). First, take one qian of raw alum (Mineral: Alumen), crush it into pieces the size of beans, place it in a silver crucible, put the crucible into the furnace, and melt it using charcoal fire. It is ideal if no lumps remain when pierced with chopsticks and stirred. Next, add three qian of high-quality nitre (Saltpeter), broken into small pieces, about three-tenths of the total amount at a time. Then, add three qian of white borax (Borax), crushed, also about three-tenths. After a short while, add more raw alum gradually until completely melted. Repeat adding small amounts of nitre and borax as before, continuing until all ingredients are added. Wait until the mixture rises above the rim of the crucible, swelling like a steamed bun, then increase the charcoal fire intensity and burn until dry. Thereafter, cover the crucible mouth with a large piece of clean tile, let it sit for an hour, then remove it. Take a small amount of real musk (Moschus), grind it into fine powder, mix with five or six spoons of clear water, and drip this mixture onto the elixir using a spoon. Return the crucible to the fire to dry thoroughly, then remove it. Place the crucible upside down on a clean surface lined with paper first, and cover the top of the inverted crucible with a bowl. Leave it for seven days, then store for future use. The product should be light and free of cracks; those with cracks are unsuitable, though they may be kept for mixing with honey or used as topical applications. When initially heating, the fire should be gentle, but not too slow, lest the alum becomes stiff and difficult to dissolve, resulting in solidification with cracks later. In the middle and later stages, strong fire (Wu Huo) must be used. If alum powder is fully melted before adding nitre and borax, they will not fully dissolve, leading to hardness and cracking. Use old crucibles that have been previously poured out from, to prevent them from bursting in the furnace. If using new crucibles, pre-heat them with charcoal before placing them in the furnace; do not place them on wet charcoal to dry, as moisture entering the crucible will cause it to crack upon heating. Some say crucibles previously used for melting silver may still contain toxic fumes. This elixir is best prepared in advance; the longer it ages, the better.

Those made by burning thatch are called Baicaoshuang (Hundred Herbs Frost). Take the soot from near the bottom of the pot; neither the center nor the edges of the pot mouth should be used. First, scrape off the top floating layer, then scrape off the middle layer. Do not scrape repeatedly, as the third layer adhering to the pot is also unsuitable.