Ancient westerners believed that metal is a living body, which can gradually grow into perfect gold, and this growth process can be artificially interfered. The way they take is to separate the form or soul of gold and turn it into base metals such as iron and copper; In this way, the base metal will have the form or characteristics of gold. The soul or form of metal is regarded as a kind of aura, mainly manifested in the color of metal, so the gold-plated silver on the surface of base metal is regarded as the transformation promoted by alchemists.
At that time, the general operation flow of an alchemist was: four base metals, copper, iron, tin and lead, were put together to melt and cooled to become colorless dead substances. This process is called "black transformation"; Then add mercury to whiten the surface of the alloy, which is called "whitening" or "silvering"; Thirdly, adding a little gold to make the alloy surface yellow, which is called "yellowing" or "gold formation"; The last step is "purification", which removes the base metal on its surface by soaking and washing, so that the alloy presents pure gold. After this step is completed, the original base metal has undergone a gradual evolution, losing its original base soul, gaining a noble soul and turning it into gold!
There were many famous alchemists in ancient China, such as Wei Boyang in the Eastern Han Dynasty, Tao Hongjing in the Jin Dynasty and Sun Simiao in the Tang Dynasty. Among these people, Ge Hong of the Eastern Jin Dynasty is the most famous. In his book "The Inner Chapter of Bao Puzi", he specifically described various chemical knowledge such as refining gold and silver pills, such as: "When you are a big iron, it is one foot and two inches high. Make a small shovel, six inches in the middle, and polish it. A kilo of halloysitum rubrum, a kilo of Xiaoshi, a kilo of mica, a kilo of ochre, half a kilo of yellow, four ounces of blue, and a kilo of coagulated water stone are carefully screened, mixed with acyl, and coated with a small layer with a thickness of two points. A catty of mercury, half a catty of cinnabar, not half a catty. Put good illegal lead in an iron pot weighing 10 kg and expose it on the stove. Lead pin contains three ounces of mercury, and those who come out early copy it with an iron spoon, which is called good or bad. Stir and take it. When the mercury disappears, put it in a small pot, cover it with mica and iron. Live in a cauldron on the stove, sell the lead and pour it into the cauldron. If there is no small pot, go to the top half inch and take the lead. Boil for three days and three nights with strong fire, which is called purple powder. Take ten catties of lead and sell it in iron ware. On the 20th, put it in bronze ware, put it in a lead pin, put purple powder in it, and stir it to turn it into gold. If you want to become silver, put mercury in an iron vessel. Three inches of purple powder has been applied, which matches the fire. When it is filled with water, it will turn silvery white. "
Although gold could not be extracted by Ge Hong's method, he discovered many material properties and changes. For example, "Red mercuric sulfide (red mercuric sulfide) decomposes red mercuric sulfide (red mercuric sulfide) by heating. Adding sulfur to mercury can generate black mercuric sulfide and then become red mercuric sulfide. The reversibility of chemical reaction is described. Another example is "Zeng Qing painted iron, iron red as copper", describing the reaction of iron replacing copper and so on.