Fu Rui watched the two men carry a load of salt to approach, and directed them to pour it aside. He then poured the earth salt into a large pot and turned it into salt water. He poured more than a dozen loads of salt water, and then scooped the salt water into the empty pot next to it.

Seeing that he was almost full, Du Zhongxiao ordered Tao Shiqi to lead his men to light coal under the pot.

Kuzi, Douzi and others from the Salt Prison were standing listlessly, watching Du Zhongxiao commanding people busy, expressionless and expressionless. In the past one or two years, the salt Prison was in a difficult life, and they lost interest in everything.

The process was extremely long. When Du Zhongxiao saw that the fire was burning strong, he left the shed and went to the official hall to talk to Feng Yuan and the others. Whether it was refined salt or boiled salt, it was technically confidential now and could not be seen by outsiders. This industry is big and has many uses, salt is still a small matter, and various by-products of nitrate and alkali will have great uses in the future. Once it is introduced to the Khitan, there will be hidden dangers.

The Khitan area north of Bingzhou is in Yanmen Village. Since the Khitan prohibits the market of horses, sheep are the largest export materials of the Khitan. In addition to tens of thousands of live sheep every year, there are also a large amount of sheepskin and a small amount of other animal furs.

Feng Yuan was very familiar with the Yanmen Village area and told Du Zhongxiao about the geographical and human feelings there and some interesting stories about his own business.

It was almost noon, and Du Zhongxiao ordered people to drink some wine, and he returned to the place where he cooked salt.

The salt-boiled person tried the boiled salt water and found that there was already salt crystals at the bottom. Du Zhongxiao ordered someone to scoop out the boiling salt water and pour it onto a cloth set up with a wooden rack next to it, so that the filtered salt water could be poured into the pot below.

The process of refining salt is nothing more than evaporation, filtration, and crystallization. However, although the cloth is simple, there are many requirements for specific operations. The more refined the salt, the better it is. If there is no subsequent filtration and crystallization, and boil the water directly in the pot, what is obtained is the earth salt in the salt field, which is of poor quality and contains too many impurities and cannot be eaten. For example, the salt water filtered into the pot can still be remade again, and after three or five times, you will get fine snowflake salt.

However, today Du Zhongxiaozhi is not in the fine salt, but in the salt of soil, so he misses this step.

After filtering all the boiled salt water, Du Zhongxiao ordered someone to take down the filter cloth. He saw a thick layer on it, as white as mud, and there were a lot of them.

When Fu Rui saw this, he hurriedly said, "This cloth is blocked and it is unbearable. Please change it to a new cloth!"

Du Zhongxiao smiled and said, "I'm not thinking about it, and what we want is the white mud on the cloth. You follow me, but wash the white mud with water a few times, then steam it out. It's like snowflakes, which is the salt we want."

Fu Rui was curious, walked up to look and looked again and said, "Is this the salt? I don't know what kind of salt it is?"

Du Zhongxiao said: "This is Glauber's salt. Whenever you use braised soil to make salt, the first time you make unearthed salt, you will receive alkali and nitrate, but at that time, the nitrate was mostly fire nitrate. The earth salt turned into salt water and boiled again, and the one produced was Glauber's salt. This is Glauber's salt and fire nitrate have different properties and different productions."

In the past, when I was in Yongcheng, Du Zhongxiao studied the chemical properties of saline-alkali earth in order to make fire and is familiar with it. In the process of using salt soil to make salt, the first step was sodium alkali carbonate and part of potassium nitrate. They were refined to separate the two. The technology in this era was very mature. Finally, the salt was refined, and the sodium sulfate was produced. The composition of saline-alkali earth in different places was different, and the proportion of these three by-products was also different. Here in Bingzhou, the most by-products were Glauber's salt and tin, and the alkali was less than that of Bozhou.

In fact, the production of earth salt in Hedong has not been cut off in history. With the development of gunpowder technology, the importance of tincture is getting higher and higher. So during the War of Resistance Against Japanese Aggression in history, salt became a by-product of tincture, and the output was very huge at that time. Du Zhongxiao did not know this history, but he had already realized that the value of earth salt on Hedong Road lies not in the salt itself, but in its by-products. In particular, tincture is also produced on Hedong Road, and the conditions for producing gunpowder are much better than those on Bozhou. At this time, there were tincture and tincture on the list of bans on the Khitan.

Fu Rui felt curious and took a few manpower to go out to refine the collected Glauber's salt. At this time, the ingredients were relatively single. After several filtration and crystallization, he obtained the product used. It was just white and slightly yellow, which was far from the snowflakes.

Du Zhongxiao saw it, and took it to the official hall.

After opening the cloth bag, Feng Yuan and others looked at the Glauber's salt inside. Du Zhongxiao said, "How? This is made from earth salt, which is best for tanning leather. This thing is prohibited along the border, and it is not common in the Khitan area. Of course, the most important thing is that there are few craftsmen there and they are also familiar with leather, so it depends on us Han people. No matter how much fur you sell, I can recruit craftsmen here and tannate them."

Feng Yuan took the cloth bag in his hand, and passed it over to the other two people. He even twisted a little and tasted it in his mouth, nodded repeatedly: "It's true that it's Glauber's salt."

Du Zhongxiao smiled and said nothing. Glauber's salt and many similar compounds are slightly astringent and salty. Where can I taste it?

Seeing that Du Zhongxiao had made many things in a short while, Feng Yuan was very calm and said, "The officials can make slurry here, so they can recruit skilled craftsmen to start this business. In fact, there are also good leather makers in the Hedong area, and craftsmen are not scarce in the countryside. The difficulty is that some people build farms and buy property to make this business bigger."

Du Zhongxiao said: "This is not difficult. As long as there are many people who know this craftsmanship, I will find enough staff even if I have the ability to rank the staff. What is lacking is that you sell enough fur and wait until it is cooked and then sell it to other places."

Feng Yuan smiled and said, "The mature leather can not only be sold to the Central Plains, but also to the north. Officials don't know that those Khitan nomads wore raw leather coats to prevent the severe cold, which are both hard and uncomfortable and easy to damage. With the mature leather, who would wear raw leather?"

Using nitro tanning to make leather is actually not an amazing skill, but in this era, there are still limited people who master it. Especially in the Central Plains, there is no habit of wearing fur and the technology is developing slowly. In the areas outside the border, there are few craftsmen and do not meet the conditions for industrialization.

Seeing the real thing, Feng Yuan did not doubt it anymore and said to Du Zhongxiao: "Since it is not difficult to make salt, the fur on my boat will be tanned locally. After we have used the meal, we will go to find a mature craftsman with the officials to see if it is easy to make."

Du Zhongxiao had no objection. Hedong is vast and sparsely populated. Not to mention that there are many sheep raising families, there are also many hunters in the mountains, and there are not a shortage of people who can tannate the skin. It takes only a few days for raw skin to tan, so it is not troublesome.

Just when Du Zhongxiao and Feng Yuan were talking enthusiastically, Fu Rui brought a bag of salt in and said to Du Zhongxiao: "Look at the signing of the verdict, the salt we refined is as white as snow, no worse than the salt removal in the south. It is not difficult to sell in the city like this. If the salt in the market is refined, it may be able to be sold. In the past, the earth salt was difficult to sell, but the quality was too low and the price was high."
Chapter completed!