Introduction: For us from ancient times to the present, how to spend the harsh winter and the unbearable summer is a major problem in life.
Whether it is cold or extreme heat, it is a natural enemy of human beings, and it can even take everyone's life. Even in ancient times, when there was no science and technology, everyone would find ways to create some comfortable conditions for themselves.
In the summer in the big city, there are two kinds of household appliances that everyone can't do without, that is, refrigerators and air conditioners.
The desire for the air conditioner has basically become an instinctive reaction, and in the face of extreme heat and thirst, everyone's first reaction is if you can eat a little cold food. As a result, ice becomes the most precious item of summer.
Our home refrigerators today can easily produce ice cubes, and everyone can experience delicious cold food at home. But in ancient times, when there was no ice machine, did everyone lose touch with ice cubes in the summer? In fact, this is not the case, the wisdom of the ancients is far higher than everyone thinks.
In the case of prehistory, we have found that in the underground, caves and other areas can always maintain ultra-low temperatures, so in the case of winter temperatures below the water can naturally thaw, a large number of ice cubes are excavated and transported to the "ice caves" that are naturally produced or professionally excavated, and the ice cubes can be stored until the summer.
As early as the case of the Zhou Dynasty, there were high-ranking officials who professionally managed ice caves in China, known as "Lingren".
First, can China make ice in ancient times?
Although it is relatively simple to extract pure natural ice in winter and survive until summer, it is clear that not everyone can have an ice cave, which in the past was also the exclusive right of the royal family and rich merchants. So could it be that ordinary people in ancient times could only bear the heat in the summer?
In fact, the laborers also exerted their own wisdom, and the most convenient and fast natural "refrigerator" in ancient times was the deep water well.
Pack a variety of ingredients and fresh fruits in bamboo baskets and hang them in the river water, and after a while you can experience the cold food. But this can be regarded as "freezing" at most, did the ancients have a way to "refrigerate"?
The truth is likely to exceed our expectations, because in the philosophical work of the Han Dynasty "Huainanzi" before 2000, it is recorded that "to build glue in winter, to make ice in summer".
"HuainanZi" was written together with the "Huainan School" assembled by Liu An, the king of Huainan in the Han Dynasty, also known as "Huainan Honglie", which is the "inner book" of the Huainan school.
In addition to the Kai Neishu, the Huainan School also wrote "outer books" that described various weather phenomena and life techniques, and the Huainan Wanbi Book is one of them. However, what is disappointing is that the entire reading of the Huainan Wanbi Book has long been scattered, and at this stage, there are only some compilations of posterity.
According to the current materials, the Huainan Wanbi Book does indeed record the way of ancient artificial ice. The original words are as follows: "Take the boiling soup and put it in the urn, close it to the new silk, and the Shen (well) in the middle of the three days into ice." "A simple translation is to put boiling water in an urn, carefully seal it with fabric, and sink it in the well for three days, and the water can turn into ice.
It sounds a little unbelievable, the river is indeed very cold, there is nothing wrong with it, but why use boiling water to make ice, isn't the effect of cold water faster? Although the temperature of the river itself is very low, it has not reached the ice level, so why can it make the hotter water freeze?
Second, what is the principle of ancient artificial ice?
For this passage of the Huainan Wanbi Book, scholars over the years have their own opinions. Especially after the modern physical expertise was transmitted to China, everyone was more suspicious of the authenticity and effectiveness of this record, after all, there are also many mythical stories in the Huainanzi.
But it is also some scholars who feel that the ancients only inadvertently learned some of the physics expertise that is now easy to ignore.
For example, Hong Zhenhuan, a scholar at Ningbo University, believes that this type of method uses the basic principle of rising water freezing point temperature in places with lower air pressure, and because the height of the well is generally deeper, the standard air pressure at the bottom of the well will be very low.
However, some scholars disagree with this view, because there was no equipment to drill in ancient times, and it is unlikely to move the depths of the well into five hundred meters.
The main point of ancient artificial ice depends on the counterintuitive point of "boiling water", which causes a reaction similar to "scorching soup effect" in the deepest part of the sealed urn, so that boiling water can quickly cool down and even freeze at the end.
The so-called scorching soup effect is that the vapor has an irreversible thermal deformation according to the porous substance, and finally causes a sudden change in temperature.
In this practice, the "silk" that seals the mouth of the urn is the porous structural substance, and the urn can seal part of the sex. So, is this guess correct?
3. Experiments on ancient icemaking
Any basic theory that is used to guide operation concretely, if it does not pass real trials, is merely speculation and empty talk.
Therefore, the scholar Li Zhichao conducted an experiment on this matter. It replaces the ceramic urn with a spherical glass bottle, in which it is filled with water and a thermometer, sealed, and then boiled the water in the water bottle, and quickly put into a pure bucket filled with cold water, which is equivalent to using a more careful and controllable method to certify the views of the ancients.
So what's the result? Li Zhichao found that at the beginning, the water in the bottle did cool down very quickly, from almost 90 degrees Celsius to more than 20 degrees Celsius at a melting point in a short period of time, but the temperature reduction after that was not so fast.
Could it be the cause of insufficient storage time? After all, the record in the Huainan Wanbi Book is to be placed for three days.
Therefore, Li Zhichao placed the Aquarius seat for many hours, and the temperature had already dropped to 7.5 ° C. He will slowly remove the seal, which can also allow the external gas to be injected slowly, which has the effect of balancing the internal and external standard air pressure.
Since then, the water in the bottle has slipped by about 1.5 ° C, and the overall temperature is around 6 ° C, which can already be said to be very refreshing, but it is obviously some distance away from the ice level, and it is more difficult to obtain the same lumpy and hard ice stored in the ice cave.
Did the ancients really make ice?
This experiment is the first detailed test of the icemaking method in the Huainan Wanbi Book, and has provided a crucial scientific research material for the academic community.
There is also a very divergent result as to whether the methods recorded in the "Book of Wanbi of Huainan" are real: on the one hand, this method recorded by the ancients can indeed rapidly reduce the temperature of boiling water in a short period of time, indicating that it is not a nonsense, but only a way of summarizing according to realistic experiments; but on the other hand, such methods do not seem to be able to bring water to the real ice level, what is the reason?
Some scholars have clearly put forward another view: perhaps this was originally a way of summarizing the daily life of laborers in reality, but the article compiling the "Huainan Wanbi Book" has not really been tested, so they do not know the expected effect of this method, so they write it into the book.
There are many examples of this view in ancient history, but at this stage, there can be no doubt that this is the case, after all, the records in the Huainan Wanbi Book are also very simple and vague, and it may be that some important processes have been ignored, resulting in unsatisfactory final results.
In general, the basic principle of making ice with hot water in ancient China has so far been a difficult point that confuses scientists.
summary:
People's intelligence is guiding this race forward, and our desire for a happy life makes us constantly challenge ourselves in technology.
Even in ancient times, when they were not advanced, the people also summed up a lot of useful experiences in their daily lives, which could make everyone get some simple happiness in the era when the main force of production was not yet developed.
Source: Science Channel Avocado
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