The addition of Fu Tianqi and Cheng Xuefeng greatly increased Jingyuexuan's strength.

The two quickly entered the role, broke up the five soldiers with rich combat experience they brought, and integrated them into the orphans of the fallen soldiers trained by Lu An for systematic training.

As for the girls of Sanssouci Fang run by Lu Yuyan, they had been engaged in intelligence gathering before, and most of them were non-combatants, and they continued to stay in Jingyuexuan, responsible for assisting Lu Yuyan in doing a good job of logistics and supply.

Lu An's attitude is that once Xia Yongtu finishes shipbuilding and training naval forces, he will inevitably invade the south on a large scale.

Chu Yin, Lu Mancang and Mu Cun accelerated the deployment of troops and generals, preparing for the final showdown with the Great Xia army, and they couldn't care about Lu An's movements.

The north and south banks of the Huai River are already tense.

And Lu An began a half-month-long retreat in the closed warehouse of Jingyue Xuan.

Although there is a huge disparity in strength compared to Xia Gang and Pu Zhen, it is imperative to rescue Lingfeng!

And his biggest reliance is the black powder that has not yet appeared in this era.

As a knowledgeable traveler, Lu An naturally knew the correct ratio of black powder.

It's just one thing to know, it's another to actually start doing it.

In the past, he didn't have the heart to compete for the world, he just wanted to live a peaceful and stable life.

Therefore, even if he knew the preparation ratio of black powder, he had never tried it, and he didn't want to rely on this kind of big killer to dominate the world.

But now it's different.

In order to save his wife and children, he had to do it as a last resort!

The correct ratio of black powder, saltpeter, charcoal and sulfur was mixed in a ratio of fifteen to three to two.

As for the granulation and what kind of polishing process, it is not in his consideration at all.

At least, he already has all the materials for making black powder, and the quantity is quite large!

To be on the safe side, Lu An first made a black powder fuse and a pill-sized gunpowder ball in the huge warehouse with the correct proportion.

Because there was no time for gunpowder granulation and polishing process, the power of the test was much worse than expected.

However, after two days of improvement, Lu An changed the outer packaging of the powder ball to rubber, which greatly enhanced the sealing of the powder ball and greatly improved its power!

It took nearly seven days for the black powder to be successfully trial-produced.

But then, looking at the mountains of various materials in the warehouse, Lu An made a difficulty.

In order to prevent the leakage of the black powder formula and the use of it by people with intentions, causing a huge disaster, Lu An had already made preparations for it long before he decided to make black powder.

In addition to the three essential materials of saltpeter, sulfur and charcoal, Lu An also specially announced the purchase of a large number of other materials in public.

Such as borax, clay, hemp rope, cloth, talcum powder, crushed iron filings and so on.

Moreover, after the purchase of these materials was over, Lu An was still not at ease, and specially told Lu Yuyan to destroy all the acquisition records this time.

This is done in order to prevent someone from getting the acquisition records afterwards and deducing the materials and proportions of black powder.

Although the confidentiality work in the early stage is good, what about the next step?

There are too many materials in this warehouse, and he has to operate it alone, and he can only finish it in the Year of the Monkey and the Year of the Horse!

In this matter, Lu An couldn't trust anyone.

After all, there was the Xiaohong incident before.

- Although Xiaohong did not betray him in the end.

But once accidentally leaked, the consequences are unimaginable!

Therefore, even if it was Ah Da and the other twenty-nine dead soldiers, Lu An did not dare to fully trust them.

However, it is obviously unrealistic to let him complete all the material proportions by himself.

Therefore, after careful consideration, Lu An finally decided to divide the black powder into several steps.

It took three days for Cheng Xuefeng to mobilize a hundred of his subordinates to accurately weigh all the materials in the warehouse, and divide each material into several piles to make a record.

Then, alone, it took another two days to mix a certain percentage of sulfur and charcoal, charcoal and saltpeter, and sulfur and saltpeter.

After some operation, Lu An divided Ah Da and them into two batches of people, and prepared the remaining materials in accurate proportions.

In this way, half a month passed.

Lu An finally appeared publicly and called Fu Tianqi, Cheng Xuefeng and Lu Yuyan together.

"Yuyan, from today onwards, you divide those people in Sanssouci Fang into two parts, and some people continue to process rubber, and I will hand over the rubber mold to you later, as for the specific quantity...... Until I call it a halt! ”

"The other part of the people specialize in processing leads and processing methods, and I will teach them later."

"Brother Fu, Brother Cheng, you each take three hundred people, take turns to enter the warehouse every other day, process the things I need, and continue to train the rest of the time."

"But remember!"

"All people who enter the warehouse must be strictly inspected, and must not bring the fire source in, otherwise the consequences will be unimaginable."

Lu Yuyan didn't ask the reason, nodded, and immediately started to act.

Fu Tianqi asked curiously, "Young Master, the big war is coming, what are you busy with?" ”

Lu An smiled mysteriously, "You'll know when the time comes......"

Seeing that there was only more than a month left before the time Chu Yin said, Lu An became more and more anxious, and only rested for two hours a day, and spent the rest of the time supervising the processing of black powder, checking the progress on the one hand, and preventing possible safety accidents on the other.

After three days, whether it was the rubber ball and lead on Lu Yuyan's side, or the speed at which Fu Tianqi and Fu Tianqi filled the rubber ball with gunpowder, the synchronization was greatly improved.

Every day, thousands of rubber balls the size of soccer balls are smoothly processed into small bombs with a length of 30 centimeters, which are carefully packed in large wooden boxes in another warehouse.

Ten days later, the number of processed pieces had even increased to nearly 3,000!

Seeing that there was no need to worry about the processing of small bombs, Lu An asked Zheng Xianjue to find ten experienced carpenters in Danyang and start manufacturing trebuchets.

"Only more than two hundred meters?"

Seeing the effect of the trebuchet, Lu An shook his head, not very satisfied.

"Masters, you have to think of a way to see if you can use the unique elasticity of our Jingyue Xuan's rubber at this time to increase the projection distance of the trebuchet and improve it as soon as possible."

With the rubber provided by Lu An, the ten carpenters immediately began the work of refining the speculative stone.

It took half a month to finally increase the projection distance of the trebuchet to about 350 meters!

"Come, Ah Da, you and Ah Er will accompany me to try the effect!"

Lu An actually Feng Ah Da and Ah Er, pulled the improved trebuchet, found a place where no one was, and after repeated experiments, observed the degree of burning of the lead from ignition to landing after projection, and finally determined the length of the lead.

Of course, during the test, Lu An did not use a real small bomb, but replaced it with a stone of the same size and weight as the small bomb.

But even so, when Ah Da and Ah Er saw the fire coming out of the fuse burning, they were still shocked!

After determining the length of the lead, Lu An stepped up the processing of the new trebuchet.

Just as Lu An was stepping up preparations for battle, Zheng Weitao, the captain of Wujiang Weishui, finally arrived at Jingyuexuan.

"Is there any movement over there in Xia Yongtu?"

Zheng Weitao's face was solemn, "Young master, after the observation of the last general, Xia Yongtu has built hundreds of warships in Jiangbei, and the training of sailors has also achieved initial results, and it is very likely that he will invade the south in the near future!" ”

Lu An sneered, "It's not Xia Yongtu who invades the south, but I, Lu An, are about to go north!" ”