Ancient people had two methods of making ice.
First, it is the kind of ice cellar in the Xixia Imperial Palace in the Tian Long Ba Bu. In winter, workers go to the frozen rivers and lakes to get ice, which must be at least half a meter thick. Hide these large ice cubes in cellars deep underground. There is generally underground water near the cellar, so the temperature is very low, close to zero. The cellar is then strictly sealed and the water is removed regularly and cannot be entered at other times. In this way, in summer, at most half of the ice cubes will melt, and the remaining half will be enough for the royal family.
The second is chemical ice making.
You read that right, it was chemical ice making, but it wasn’t called chemical ice making at that time.
This has to mention an item called "saltpeter", the main component of which is potassium nitrate. The biggest feature of this thing is that when it comes into contact with water, it will absorb a lot of heat, causing the surrounding temperature to drop.
The ancient Chinese were very smart. Otherwise, how could they have come up with the "Four Great Inventions"?
At the end of the Tang Dynasty, people mined saltpeter when producing gunpowder. It was discovered that when saltpeter dissolves in water, it absorbs a large amount of heat and cools the water until it freezes. Since then, there has been a method of making ice in summer. Later, traders gradually added sugar to the ice to attract customers. By the Song Dynasty, there were more and more varieties of cold food on the market. Merchants also added fruits or juices, and even added fruit pulp and milk to the ice. This was very similar to modern ice cream. In other words, contemporary ice cream and even Haagenda. The originator of Sri Lanka.
In the 13th century, Marco Polo brought this ice cream making method back to Italy and later spread it to France. One of Queen Catherine's personal chefs developed a semi-solid ice cream mixed with cream, milk, and spices and engraved it with patterns.
The specific operation is as follows: first find a large basin and pour water into it, then find a small basin and put some water in it. Place the small pot into the large pot.
Please note one important point: the water surface in the small basin should be lower than the water surface in the large basin. Then, slowly pour an appropriate amount of saltpeter into the large basin. When saltpeter meets water, it begins to react quickly and absorb heat. After a while, the water in the small basin gradually turned into ice.
This method was once very popular in the Song Dynasty. After making ice through this method, cold drinks were also made.
This shows that the people of the Song Dynasty were very good at enjoying themselves. Although fighting was average, few dynasties could compare with the Song Dynasty in terms of enjoying life.
In a poem written by Yang Wanli in the Song Dynasty, he wrote: On a Zhuowu day in June in the Imperial City, the people in the city were cooking and sweating like rain. The sound of selling ice comes across the water, but pedestrians are not satisfied.
However, this method of making ice from saltpeter also has two major drawbacks. First, the amount of saltpeter used is very high, at a ratio of about one to one. That is, one kilogram of saltpeter can make one kilogram of ice. Although it can be used repeatedly, it has not become popular and popular. not easy. Second, the quality of the ice produced is average and can be used to make drinks, but it is very difficult to make large ice cubes, so people who are not royal family members cannot afford it.
Glauber's salt, a traditional Chinese medicine name. It is a crystal of the sulfate mineral Glauber's salt, which is processed and refined. Mainly contains aqueous sodium sulfate (Na2SO4·10H2O). It is distributed in most parts of the country. It has the effects of purging and laxative, moistening dryness and softening hardness, clearing fire and reducing swelling. It is often used to treat stagnant heat, abdominal fullness and pain, dry stools, intestinal carbuncle swelling and pain, etc.; external treatment of mastitis, hemorrhoid swelling and pain.
This product is in prismatic, rectangular or irregular block or granular shape. Colorless, transparent or off-white translucent. It is brittle and fragile, and the cross section has a glass-like luster. The smell is slight and the taste is salty.
It can be harvested and processed throughout the year, but autumn and winter are preferred because the temperature is low and crystallization is easy. Take natural impure Glauber's salt, commonly known as soil salt, add water to dissolve it, leave it to allow impurities to precipitate, filter, heat and concentrate the filtrate, let it cool and the crystals will precipitate, take it out and dry it in the sun, commonly known as "picture salt".
It is mostly found in seaside alkaline soil areas, near mineral springs, salt fields and in humid caves. It is distributed in most parts of the country.
In ancient times, there were not many places to find potassium nitrate ore. People mostly obtained it from the soil at the base of walls of old houses, toilets, pig pens, etc. Soil containing more nitrogen elements will oxidize nitrogen-containing organic compounds into nitric acid due to the action of bacteria and other microorganisms. The cations in the soil generally include calcium, magnesium, sodium, potassium, etc., thus generating nitrates. Soil containing more nitrates is called nitrate soil. The ancients soaked such nitrate soil with plant ash water (rich in potassium carbonate) and allowed the potassium carbonate to react with calcium nitrate, magnesium nitrate and sodium nitrate to obtain a solution rich in potassium nitrate. After the water evaporated, saltpeter (potassium nitrate crystals) was obtained. Because this kind of saltpeter is obtained from the soil, it is also called soil saltpetre.
Since the sources of nitrate are not abundant, large-scale preparation of nitrate is difficult. Moreover, because Glauber's salt can also be obtained from alkaline soil, it is also called earth salt, and both types of saltpeter can be used to tan fur. Therefore, Glauber's salt with sodium sulfate as the main component and fire saltpeter with potassium nitrate as the main component are closely related to some ancient people. It's easy to get confused.
Saltpeter? Ask Liulichang to get more of it. It's not easy for ordinary people to get, but it's very convenient within the system. With repeated use, it's enough for your pharmacy in the summer. It's impossible to make money by making ice.
However, if you have nitrate, you can try to get some nitric acid to synthesize nitroglycerine. It is not only a raw material for the further development of gunpowder, but also a good medicine for treating diseases.
It is used as a vasodilator in medicine. It is made into 0.3% nitroglycerin tablets and administered sublingually. It has a rapid and short-lived effect and treats angina pectoris caused by coronary artery stenosis.
Nitroglycerin tablets should not be swallowed, but placed under the tongue. This is because swallowed nitroglycerin must pass through the liver during the absorption process, and most of the nitroglycerin is inactivated in the liver, greatly reducing the efficacy of the drug. There are many blood vessels under each of our tongues, medically called the sublingual venous plexus. Nitroglycerin is very easy to dissolve. When you hold it under the tongue, the dissolved medicine can directly enter the blood. Therefore, it not only takes effect quickly, but also is very effective. Will not decrease. Nitroglycerin tastes slightly sweet and irritating, so qualified nitroglycerin should not only dissolve quickly, but also have a burning sensation when held under the tongue, which is also a sign that the drug is effective.
Nitroglycerin is mainly used clinically for first aid, and has good therapeutic and defensive effects on coronary heart disease, angina pectoris, lowering blood pressure, and congestive heart failure. Nitroglycerin is used clinically as an oral drug and as an injection.
