When they got closer, the villagers laughed in amazement when they saw that most of the returnees had turned black.

The coal is black, and if anything sticks to it, it will definitely be covered with black ash.

The subjects and slaves carried sacks of coal all the way, and the sacks were not sealed, and the black ashes would surely fall, and naturally they would be black.

The ridiculed subjects were not annoyed.

They proudly puffed out their chests to those who laughed at them, and spoke eloquently about their hardships and the importance of the black stone to the title.

As a result, the ridiculers stopped laughing and looked with envy at the group of subjects who had become black.

Lü Wu stood at the gate of the village, watching the huge procession enter the village, and loudly announcing the rewards for the samurai and subjects.

The rewards are great.

The samurai and the subjects who followed out all smiled and smiled.

In fact, whether it was a samurai or a subject, it was only natural for them to do things for their lords.

In other words, they are protected by the lord, and working for the lord is a reward, and it is reasonable to have no salary.

Because the lord valued something, he thought that he should be rewarded, which was another gain for the samurai and his subjects.

After announcing the reward, Lu Wu explained how the slaves brought back should be arranged, and he didn't have to worry too much about the rest.

For example, grain, cloth and other things, the old man will record and put them into the warehouse.

Coal is delivered to the workshop.

Cheng Ying was very curious about how Lu Wu was going to use the newly arrived slaves, so he asked if he had any questions.

"The irrigation system in my territory doesn't work." Lu Wu really didn't find any irrigation system, and said: "There are streams in the territory, there is no shortage of water sources, and you can dig ditches and distribute irrigation systems. ”

Not to mention, at this time, most of the countries in the Central Plains really do not have a perfect irrigation system, and they generally use water-loading tools to carry the irrigation method on their shoulders.

In the Chinese cultural circle, Qi was the first vassal state to use national resources to build a systematic irrigation system. (Done during the Guan Zhong period)

By the Warring States period, the Qin state had become the most complete power with the most complete irrigation system, and far surpassed the other countries.

However, for a long time, Qin's medical technology was far ahead of other countries.

For a long time, the Qin State relied on medical technology to improve diplomatic relations with various countries and maintain friendly diplomatic relations with foreign countries, and they had a team walking around the world.

That medical team is called Bian Que by the nations.

(During the Yellow Emperor, there was a divine doctor called "Bian Que", and the medical organization in the Chunhua cultural circle was also called Bian Que, until a very good Qin Yue person (name) was recognized, and Bian Que was named by Qin Yue people)

Because there was no relevant concept, Cheng Ying was stunned when she heard it.

Lu Wu ignored the stunned Cheng Ying, went back to freshen up first, tied a ponytail casually, and rushed to the workshop with wet hair.

The craftsman had already seen the benefits of burning coal before, and when he learned that Lu Wu had brought back a lot of coal this time, he waited with his eyes open.

Last time, the coal was only enough for Lu Wu to conduct a small test, and there was no big movement.

"Start the furnace!" Lü Wu ordered the fire to be lit, walked to a hut, and when he came out again, he personally carried a basket of charcoal. He had too much to experiment, and told the craftsman, "Go get some horse urine." ”

The craftsman didn't know what Lu Wu was doing with horse urine, so he went with a lot of confusion.

After thinking about it, Lu Wu let the people who didn't need it leave, leaving only the craftsmen he wanted to use, as well as the three warriors Qing, Lin, and Zhi, who had been loyal to the old Lu family for many years.

He did it, of course, to maintain the necessary secrecy, and the samurai ensured his own safety.

Then, he asked Nao to get animal fat.

Horse urine and animal fat, of course, for quenching!

The furnace had been heated enough, and Lu Wu personally put in the iron ingot, waited for the iron ingot to melt, and then lifted the entire furnace with a tool, and poured the molten iron into the mold.

The next step is to forge it.

Lu Wu's small body, of course, can swing the hammer with strength, but the strength is not enough, and the staying power is not good.

He instructed the craftsmen to do a repetitive forging, which was cooled and then melted into a furnace to melt molten iron.

Again and again it was melted and forged, and it was repeated hundreds of times.

This is the removal of vein slag from the iron, making the iron more pure.

The day passed in the midst of repeated forging.

In the next few days, the repeated forging operation was still carried out, and the finished products were looked at separately and the rest of the experiments were carried out.

For example, limestone is used in the smelting process to remove certain impurities from iron ore.

It wasn't until Lu Wu felt that the forged iron was sufficient, and then proceeded to the second step.

On the twelfth day, Lü Wucai had the craftsmen smash the charcoal and pound it into powder.

The iron is thrown back into the furnace, a portion of the weighed charcoal powder is added, and the two materials are carefully stirred to homogenize the two materials.

When it is taken out for forging again, it is no longer a random swing of the hammer, but the iron is beaten into a long shape.

At this step, when heated again, it will not completely melt into molten iron again, but will only cause the long shape to be burned red.

In addition to extraction, the quenching method is a double quenching method using horse urine and animal fat.

A series of steps made the participating craftsmen stare at each other.

They didn't know that there were so many steps to striking iron, and there were so many tricks to be done.

"Swing!" With full of expectations, the craftsman put the long iron on the wooden table, and immediately leaned over, staring at the things, while secretly commenting: "Look at the texture is such a thing, I don't know if the formula ratio is right, whether it has reached the desired hardness." ”

Whether it is hard or not depends on the test.

Lu Wu personally placed the long iron on top of the two stones that had no stress point in the middle, and said to the craftsman holding the hammer: "Smash." ”

Even if the craftsman has no culture, he knows that he wants to test the hardness, so he has a momentum and smashes it hard.

A metallic symphony appeared.

The hammer smashed into the long iron, and the elastic force caused the hammer to swing away, and the long iron was dropped to the side with a single flick.

Lu Wu, who walked forward quickly, picked up the long piece of iron, held it in his hand and examined it repeatedly.

The long strip of iron bent to a certain extent, but did not shatter.

Lü Wu placed the long iron on the stone table again, and asked the craftsman to smash it repeatedly to see if it would break or shatter.

After checking again, he couldn't control the excited heart, and shouted loudly: "Lao Tzu is really awesome! ”

Carbon content of 2.1~4.3% is pig iron, which is characterized by hardness, brittleness, castability and non-forge.

Carbon content of 0.03~2.1% is steel, which is characterized by hard and tough. Can be cast and forged.

The carbon content is less than 0.033% wrought iron, and it is soft.

Carbon content greater than 4.3% is scrap iron.

The craftsman couldn't understand what Lu Wu was shouting.

They could understand Lu Wu's expressions and actions, and they became excited after knowing that they had succeeded.

Although it took many days, Lu Wu was full of joy when he succeeded in making it the first time, but he didn't stop it immediately.

In the following period, he repeatedly changed the ratio of iron to charcoal, or instead of adding charcoal, he added pulverized coal to the iron.

At the same time, the double quenching method is no longer used, and horse urine or animal fat is applied separately, and cold water quenching is also carried out.

Different steps.

Different material ratios.

Every time the results are different.

One day, he was busy until late at night, and Lu Wu, who was originally white and clean, became a dirty person again, but he smiled extremely satisfied.

After learning that the work would be temporarily suspended, the craftsmen were no longer happy, and they frequently looked at Lu Wu with evasive eyes, and their expressions were still full of worry and fear.

Lu Wu noticed the actions of the craftsmen and looked at the past......