In "Tiangong Kaiwu", alum stone is widely used. There are five types of alum stone, and its main use is to help with dyeing. In dyeing workshops, when fabrics are dyed, alum stone can be used as a mordant. For example, indigo dyeing cloth, assisted by alum stone, can make the color adhere more firmly, the color is also brighter and longer lasting, and the dyed cloth will not fade for a long time. This is an important function in the textile dyeing industry.
Furthermore, alum stone is also indispensable in the papermaking industry. In the process of papermaking, the fibers in the pulp need to be better interwoven and fixed. Adding alum stone to it can help the pulp form, make the paper smoother and tighter, and enhance the toughness and quality of the paper. In this way, the paper produced can meet many needs such as writing and printing.
When smelting metals, alum stone can also play a role. In the smelting of some metal ores, it can be used as a flux to reduce the melting point of the ore, promote the separation of metals and impurities, improve smelting efficiency, make metal extraction more pure, improve metal quality, and occupy an important position in the metal smelting process.
In addition, in the tanning industry, alum stone is used for leather tanning. It can shrink and fix leather fibers, enhance the corrosion resistance and durability of leather, and the leather tanned by it is soft and tough, not perishable, and can be stored and used for a long time, greatly improving the quality and service life of leather products.
In summary, alum is an important material in dyeing, papermaking, smelting, tanning and other industries, which has a profound impact on the development of many traditional crafts.

Carbon disulfide is a colorless liquid that is volatile, has a special odor, and is highly toxic. It is highly flammable, and can easily burn and explode in case of open flames and hot topics. Steam and air can form explosive mixtures. It is widely used in industrial fields, such as as as solvents, extractants, etc. However, extreme caution is required when using it.
The main component of saltpeter is potassium nitrate, a white crystalline powder, with a salty and cold taste. It has unique physical properties. It is easily soluble in water, and the solubility increases significantly with increasing temperature. When heated, it decomposes and releases oxygen, which is highly combustible.
Saltpeter has various uses in ancient times. First, it is used to make gunpowder. Saltpeter is the key ingredient in the gunpowder formula. Mixed with sulfur and charcoal in a specific ratio, it can be made into a powerful gunpowder, which has extraordinary effects in military, fireworks and other fields. Second, in ancient refrigeration, the use of saltpeter's heat-absorbing characteristics when dissolved in water is used to achieve cooling, such as summer ice making. Third, saltpeter is also used in the field of medicine. It has certain medicinal effects and can be used as medicine to treat diseases and save people.
Carbon disulfide and saltpeter have different properties and play unique roles in different fields. However, their characteristics need to be fully considered when using them to ensure safe and effective application.

The chemical properties of dienyl acetyl groups are particularly important. This group contains the structure of alkenyl and acetyl groups, and its properties are active. It has a wide range of uses in the field of organic synthesis. The alkenyl group is unsaturated and can perform addition reactions. When it encounters electrophilic reagents, such as halogens, hydrogen halides, etc., it can quickly combine with it to form new carbon-halogen bonds or carbon-carbon bonds. The acetyl group gives it a certain nucleophilicity, which can be used as an offensive end in nucleophilic substitution reactions, and reacts with substrates such as halogenated hydrocarbons to expand the molecular structure.
Naphthalene is a typical example of thick ring aromatic hydrocarbons. Its shape is white crystalline and has a special aroma. The chemistry of naphthalene is unique in aromatic hydrocarbons. Due to the existence of the conjugated system, naphthalene is relatively stable, but it has a typical reaction of aromatic hydrocarbons. First, naphthalene can undergo electrophilic substitution reactions, such as halogenation, nitrification, sulfonation, etc. Taking halogenation as an example, under appropriate catalytic conditions, halogens can replace the hydrogen on the naphthalene ring, and the reaction mostly occurs at the α position, and the electron cloud density at the α position is relatively high. Second, naphthalene can participate in oxidation reactions. Under the action of strong oxidants, naphthalene rings can be broken, generating carboxylic acids, quinones, etc. Third, the hydrogenation of naphthalene is also quite common. Under suitable catalysts and conditions, naphthalene can be partially or completely hydrogenated to obtain products such as hydrogenated naphthalene. Most importantly, dienyl acetyl groups are active and changeable, and naphthalene has distinct characteristics in aromatic hydrocarbon reactions, and both have an indispensable position in the process of organic chemistry.

The synthesis of dichloroacetoxy groups has been investigated by Fang family throughout the ages, and the methods can be roughly described as follows:
First, dichloroacetic acid and alcohols are used as substances, accompanied by suitable catalysts, and esterified. In this way, alcohols are selected differently, and the resulting products are also different. However, it is necessary to pay attention to the reaction conditions, such as temperature, duration, and catalyst dosage, which are all related to yield and purity. If the temperature is too high, side reactions may occur, resulting in impure products; if the temperature is too low, the reaction will be slow and take a long time.
Second, it is obtained by halogenation. Taking a compound containing hydroxyl groups as the substrate, when encountering a halogenated reagent, the hydroxyl group is replaced by a halogen atom, and then a dichloroacetoxy group is introduced. This way, the amount of halogenated reagents needs to be carefully controlled and the reaction environment. If there are too many halogenated reagents, it is easy to cause the harm of excessive halogenation; if there are too few, the reaction will not be completed, and the amount of product will be small.
Third, with the help of acylation reaction. Select dichloroacetyl halide or acid anhydride, interact with a compound with active hydrogen, and acylate to obtain dichloroacetoxy. In this process, the choice and dosage of acid binding agent are quite important, which can adjust the pH of the reaction system, promote the positive reaction, and avoid the
Fourth, the method of ester exchange is used. Take dichloroacetate and another ester, and exchange ester groups with the help of catalysts to achieve the synthesis of dichloroacetoxy groups. This approach requires strict reaction conditions, and the catalyst activity and reactant ratio need to be precisely adjusted to obtain ideal results.
All these methods have their own advantages and disadvantages. In practice, when taking into account the characteristics of the desired product, the availability of raw materials, cost considerations and many other factors, carefully choose to obtain the optimal synthesis path to prepare dichloroacetoxy groups.

Mercury is one of the hardware, its nature is fluid, and it is liquid at room temperature. It is commonly used in alchemy. However, it is toxic, and many matters need to be paid attention to when using it.
First, it is related to storage. Mercury is highly volatile, so it must be sealed and stored in a cool and well-ventilated place. If you use the analogy in "Tiangong Kaiqi", it should be like a delicate weapon hidden in the mouth, protected from high temperature and sun, to prevent it from escaping. In the past, alchemists also knew to use special bottles and cans to hold mercury and bury it in a damp place to make it stable.
Second, during transportation. Since mercury is in a flowing state, the container must be strong and tight to prevent leakage. When handling, the movement should be gentle, do not make bumps and collisions. I still remember that in ancient times, when transporting mercury, a thick lead box was used as a device, and the outside of the box was wrapped with hemp flocs and other materials, and placed in a stable sedan. Be careful on the road, lest it spill.
Third, the operation process. When operating mercury indoors, it must be well ventilated, preferably in the open air or in a ventilated place. If indoors, open windows and windows to allow air to circulate. When the ancients refined alchemy to operate mercury, they often used to open courtyards and set up bellows to help ventilate, and the operator often covered his mouth and nose with a cloth towel to prevent mercury gas from entering the body.
Fourth, protective measures. When exposed to mercury, it is advisable to wear protective clothing and gloves to avoid direct contact with the skin. People who used to make alchemy, although they did not have complete protection today, also know to wrap their hands in leather or thick cloth, and operate with caution. After the operation, they must clean their hands with clean water to prevent mercury toxicity.
Although mercury has its uses in alchemy and other fields, its toxicity is very serious. During storage, transportation and use, a little carelessness can easily cause mercury poisoning, so everything needs to be paid attention to.