The performance of the sun today gives me this feeling:
Under the attack of the heat wave, Xiaobian realized that in addition to the refrigerator can save my life, only a glass of "cold happy water" can bring me back to life. But while I was drinking a cold drink, I also thought about a question:
How did humans refrigerate food before the invention of the refrigerator? You can't always try a cold drink in the summer, can you?
In fact, human use of refrigeration dates back thousands of years. If you want to divide it into types, the refrigerator wisdom of the ancients can be regarded as the era of natural refrigerators.
(Image courtesy of LSGScience)
"Ice cellar" storage is one of the earliest natural ways of "cooling", that is, storing ice cubes in winter and placing them in ice caves for re-enjoyment in summer.
This cooling technique is primitively simple, but very effective. People began using it thousands of years ago until the 19th century.
In order for ice to melt, it needs to absorb heat, so when making ice cream, it must be cooled internally and sealed externally. Ice tanks are generally similar to semi-basements, partially located underground, near natural ice sources such as rivers and freshwater lakes, which are convenient for extraction and storage.
At the same time, people will cover the ice with dust, which has high thermal conductivity and can be considered the standard layer of ice. If handled properly, this will keep the ice in place for several months and last until next winter.
Many ancient civilizations used this method to store ice. China was one of them, and they did it in 1000 BC. According to records, "the ice is cut and washed on the second day, and the ice is collected on the third day". Fragment of "Lingyin".
The Song Dynasty also set up ice storage wells. There are also many types of ice cream delicacies, such as mixing sugar, fruit, juice and ice cream. In the Yuan Dynasty, people added fruit and milk.
Traces of history left by igloos can also be seen in some street names and locations:
It should be noted that in China, ice storage equipment is very special, such as "ice cups", often referred to as old-fashioned refrigerators:
(Sengoku Bronze Ice Mirror)
Its appearance is simple and generous, and the internal structure is ingenious. Interestingly, people can put ice cubes in copper bowls so that the wine in the cellar will be colder and become an ice drink to cool off;
But if winter comes, you can also heat the water, and the wine will turn into warm wine to warm the body...
This is not only wisdom, but also art.
Romans and Jews also loved to make chilled drinks. The Romans took snow from the mountains, stored it in pits and covered it with such a filter.
However, in dry air such as Egypt, people choose another cooling method, the "evaporative cooling method". We know that evaporation can absorb heat and have a cooling function, a physical phenomenon discovered by humans a long time ago and used in the use of refrigeration.
(The water on the ground is evaporating)
In a hot climate, the food will not be kept fresh for a long time, and some fruits and vegetables are difficult to survive a week. So people will use this kind of technology to make fresh-keeping tools for their own food, generally known as zeer.
This is an "ice" box consisting of two clay pots, which is also jokingly called a jar-within-a-tank refrigerator.
Zeer is simple to use, small cans are put into large tanks, and the gap between the two is filled with sand.
The next step is to add water to the sand to keep it moist.
At this time, the outer tank will generally have multiple holes to facilitate the air out, and the internal tank will generally use some local materials to make waterproof facilities, and the whole device will be placed in a ventilated and dry place.
Finally, some unpickled foods such as vegetables and fruits are placed in the inner jar, covered with a damp cloth, and enter the refrigeration mode.
At high temperatures, the moisture in the sand will gradually evaporate, and at the same time, during the endothermic process, it will cause the temperature to drop and prolong the storage time of the food inside. It is understood that unless the climate is extreme, the ingredients can be kept fresh for about 20 days.
Speaking of which, the "evaporative cooling method" can still play a life-saving role in the early 90s of the 19th century, and the Coolgardiesafe simple refrigerator invented by Australian gold explorers basically uses this principle. The invention also delayed food decay, increasing the explorer's chances of survival.
However, with the progress of history, summer ice is no longer a luxury item exclusive to the rich and aristocratic, and it is in the 19th century that the era of natural cooling has reached its peak, and people began to collect ice on a large scale with commercial awareness and sell it.
In 1825, ice merchant Nathaniel Wyeth invented the horse-drawn ice cutter to make cutting ice more efficient. Merchants even packed ice on ships as ballast, covered with wood chips, and sent them from Europe and North America to Asia.
In the 30s of the 19th century, household wooden refrigerators have appeared, which are actually very similar to Bingjian, but simpler and more close to the people. Part of their structure is insulated, and drip trays are designed to collect melted water and empty it once a day.
At this time, the demand for ice rose again, and it is understood that from 1843 to 1856, Boston's consumption jumped from 6,000 tons to 85,000 tons.
However, the era of natural refrigeration did not go further, but came to an end in the 20th century, followed by the rise of artificial mechanical refrigeration.
Since Scottish scientist William Cullen first discovered mechanical refrigeration for humans in the 1840s, inventors have been plagued by research and development failures, commercial competition, traffic and environmental damage, and eventually refrigerators have become daily necessities.
The operation of the "refrigerator" is no longer a big box or a big house that requires ice cubes and depends on the weather. People use science not only to provide refrigerators to preserve information and refrigerate, but also to "freeze" ice.
In short, thanks to technology, we can open the refrigerator and enjoy our favorite cold drinks.
In addition, I hope that the technology will be more advanced. After all, it's already 2019. They are all full-fledged refrigerators, and they should slowly learn to grow their own ice cream, cola and watermelon...
(The pictures in this article come from the Internet and are for exchange and learning purposes only)
Reference:
Source: Madness Pill Science
Creator: Major Tom
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