Arsenic toad, that is, the toad venom produced by the processing of toad crisp, its main use in ancient times and medicine and alchemy related.
In medicine, "Compendium of Materia Medica" and many other books are recorded. Toad's venom is warm in nature, refreshing in taste, poisonous. After proper processing, it can be used as medicine to treat diseases. It has the effect of detoxifying, reducing swelling, and relieving pain. Carbuncle, sore throat and other diseases are often treated. In case of unknown swelling at the beginning of the poison, the toad crisp with alcohol, applied to the affected area, can make the swelling dissipate. For toothache unbearable disease, can also use a little toad crisp, placed on the pain, can relieve pain. Because it contains ingredients such as toad poison and toad toxin, it has specific effects on the human nervous system, cardiovascular system, etc., and can adjust the imbalance of yin and yang in the human body, achieving the purpose of healing and saving people.
In the field of alchemy, the ancients were keen on alchemy to seek immortality or to refine miraculous medicinal pills. Toad venom is regarded as one of the important raw materials for alchemy because of its unique properties. Alchemists believe that toad is born in a damp place and has a unique yin energy, and its venom contains some mysterious power. In the complex process of alchemy, toad crisp is added, or it is expected to change the nature of the medicinal pill and give the medicinal pill special effects. Although from the perspective of modern science, this concept has no scientific basis, but when the ancient alchemy culture prevailed, toad crisp occupied a place in the raw materials of alchemy.

Mercury, commonly known as mercury, is a liquid metal with unique physical properties. It is a flowing liquid at room temperature, with a silver-white and metallic luster, just like flowing silver, shining brightly.
The density of mercury is very high, about thirteen times that of water, reaching 13.59 g/cm ³. Due to its high density, if mercury is placed on top of other liquids, it can often sink to the bottom. Its fluidity is excellent, and it is difficult to gather when it is slightly exposed to external forces. It is like a pearl walking on a jade plate, changing rapidly.
The melting point of mercury is extremely low, only -38.87 ° C, so it is a liquid at room temperature. Its boiling point is 356.6 ° C. This property makes mercury prone to state changes in a specific temperature environment.
Mercury has a high surface tension, so it often aggregates into a ball on a flat surface, like a round silver bead, which is not easy to spread. This property also makes it form a special meniscus on the edge and wall of the container.
Mercury has good electrical conductivity and is widely used in the electrical field. Although it is a metal, it is different from common solid metals. It exhibits the electrical conductivity of metals in a liquid state, which is truly unique.
However, mercury is also toxic, and its vapors and compounds can cause serious harm to the human body. If you inadvertently inhale mercury vapor or accidentally ingest mercury compounds, it can cause damage to the nervous system, kidneys, and other organs, causing various diseases. Therefore, when using and disposing of mercury, you should exercise extreme caution.

Mercury, commonly known as mercury, is the only metal that is liquid at room temperature and pressure, and its chemical properties are unique.
Mercury is chemically stable, and it is difficult to react with oxygen in the air at room temperature. However, when heated to a specific temperature, mercury can combine with oxygen to form mercury oxide. This reaction can be shown as: $2Hg + O_2\ Delta }{=\!=\!=} 2Hg O $.
Mercury has certain metallic activity and can react with many oxidizing acids. If co-heated with concentrated sulfuric acid, mercury can be oxidized to form mercury sulfate, sulfur dioxide and water. The chemical reaction equation is: $Hg + 2H_2SO_4 (concentrated) \ stackrel {\ Delta }{=\!=\!=} HgSO_4 + SO_2\ uparrow + 2H_2O $. When reacted with nitric acid, the product is also different due to the concentration of nitric acid. Concentrated nitric acid reacts with mercury to form mercury nitrate, nitrogen dioxide and water, that is, $Hg + 4HNO_3 (concentrated )=\!=\! = Hg (NO_3) _2 + 2NO_2\ uparrow + 2H_2O $; when dilute nitric acid reacts with mercury, mercury nitrate, nitric oxide and water are formed. The reaction formula is $3Hg + 8HNO_3 (dilute )=\!=\!= 3Hg (NO_3) _2 + 2NO\ uparrow + 4H_2O $.
Mercury can form alloys with certain metals, which are called amalgams. Many metals can form amalgams with mercury, such as sodium, potassium and other active metals. Amalgam has unique applications in metallurgy and other fields.
However, mercury is also highly toxic, and its vapors and mercury compounds can cause serious damage to the human body. When using and handling mercury, strict protective measures must be taken to prevent mercury poisoning.

In "Tiangong Kaiwu", the method of making caramel is quite exquisite. The raw materials are more glutinous rice, corn and the like.
First cook the glutinous rice or corn, and wait for it to cool slightly, then mix with malt. Malt is also an important thing for fermentation. The two are in harmony, placed in a warm place, so that it can ferment. Malt contains enzymes, which can make the starch in rice turn into sugar, which is the key to the generation of caramel.
When fermenting, you need to take care of the ingredients carefully and check the temperature and humidity. If the temperature is too high, the fermentation will be too fast, and the sugar taste will not be good; if the temperature is too low, the fermentation will be slow or even stagnant. When the fermentation is appropriate, the mixture of rice and malt can be seen to gradually produce juice, which is the prototype of caramel.
Then, scoop out the juice and put it in a pot to cook. During the torment, the firepower needs to be moderate. At first, the fire can be slightly fierce, so that the juice boils and the water gradually evaporates; then the fire gradually slows down to prevent the sugar from burning. During the torment, keep stirring to make it evenly heated.
As the water evaporates, the juice gradually thickens. At this time, it is necessary to judge the heat of the caramel with experience. It is recommended to drop a little caramel in cold water. If the caramel solidifies quickly, and the texture is flexible and does not stick to the teeth, the heat is just right. In this way, the caramel is completed, its color is yellow and translucent, sweet and mellow, which can add color and flavor to the diet, and can also be used as a medicinal guide, etc., with a wide range of uses.

Alchemists should pay attention to all things in the process of use. First, choose the most important place. In the place of alchemy, it is advisable to choose a quiet and clean place, away from the hustle and bustle and filth, so that the spiritual energy can be gathered and not disturbed by outside. Such as deep mountain valleys and secret rooms of Taoist temples, it is a good choice. If you are in a noisy place in the market, the heart is difficult to calm and the qi is difficult to coagulate, and alchemy is easy to lead to failure.
Second, the seasons are different. When alchemy needs to be in line with the sky, the yin and yang of different solar terms change differently, which has a great impact on the refining of alchemy. If the yang energy rises in spring, it is advisable to refine the pill that generates hair; if the yin energy is prosperous in autumn, it can refine the medicine that converges. The winter solstice is born in the sun, and the summer solstice is born in the shade. At these key nodes, special attention should be paid to the control of the temperature and time of alchemy. According to the method of changing the tone of alchemy in the sky, the effect of alchemy will be obtained.
Third, the materials should be carefully selected. The materials for alchemy are fundamental, and the quality depends on success or failure. You must choose high-quality and pure things, such as gold and stone, which need to be pure in texture, and herbs should be picked at the right time and the place of origin. You must not be greedy for cheap prices and use inferior materials, otherwise there will be many impurities in the pill, which will not only be difficult to achieve, but may be toxic. And the material compatibility is also fixed. According to the proportion of the pill prescription, one more point will be too much, and one less point will not be enough. < br Temperature is the key to alchemy, divided into gentle fire and martial fire. Martial fire prompts the delivery of medicinal power, so that the materials can be quickly fused; gentle fire slowly nourishes and refines, so that the medicinal pills can be formed and sublimated. When to attack with martial fire and when to simmer slowly with gentle fire depends on the stage of alchemy and the characteristics of the material. If the heat is too strong, the pill will be easy to burn; if the heat is insufficient, the medicine will not be able to become a pill. This is measured, and the alchemist needs long-term practice and perception in order to grasp it accurately.
Fifth, the state of mind is peaceful. When alchemy, the mind needs to be calm, the mind needs to be dedicated, and it will not be disturbed by foreign affairs. If you are upset, the operation is easy to make mistakes, which will affect the quality of the medicinal pills. If you enter the furnace Therefore, before alchemy, one should abandon distracting thoughts and make one's state of mind like still water, so that one can focus on the path of alchemy and become a high-quality elixir.