At the beginning of the Ming Dynasty, firearms officially entered the period of large-scale use, although the pure firearms force of the Shenji Battalion would not be established until Zhu Di was in power, but now firearms have begun to be equipped on a large scale in the army, and almost every expedition of the Ming Dynasty will use a large number of firearms.

Gunpowder is the foundation of firearms, but the preparation of gunpowder by Ming craftsmen is too primitive, when Li Jie visited before, he saw that the craftsmen put saltpeter and sulfur without any treatment, so directly grind and use, you must know that these two materials are minerals, must carry all kinds of impurities, if not purified, it will definitely affect the power of gunpowder.

Li Jie personally demonstrated the method of purification, the purification of saltpeter is very simple, it is nothing more than to dissolve saltpeter in water and filter impurities, and then heat and evaporate crystallization, so as to obtain pure potassium nitrate, of course, if the purity is higher, you can use this process several times.

In contrast, the purification of sulfur is more troublesome, it needs to be heated and melted, some impurities are filtered out, and then heated to boiling to vaporize, and pure sulfur can be obtained after condensation.

Sulfur needs to use a condenser, if you let people build it, it will take at least a few days, but Li Jie asked people to find a still for distilling spirits, the distillation of wine and the purification of sulfur are the same, so the equipment can also be general, of course, the efficiency is not too high, it will definitely need to be redesigned in the future, and now it can only be improvised.

As the sulfur heated and boiled, a strong smell of sulfur spread out, and the smokers were a little untenable, but Li Jiangtou and these people had been dealing with sulfur all year round and didn't care about the taste.

The melting point of sulfur is as high as more than 100 degrees, so after vaporization, it will immediately crystallize when it is slightly cold, and when the distillation is over, the upper layer of the still has formed a thick layer of sulfur, and after people scrape it off, it is very pure sulfur.

After the saltpeter and sulfur are purified, the charcoal does not need to be purified, this thing was originally fired from wood, and the craftsmen of the Ming Dynasty have figured out that the charcoal used in gunpowder is better than willow charcoal.

"Okay, because of the limited time, I won't make wet gunpowder, and there will be a craftsman to mix these three materials in the best proportion, and then test the power of this gunpowder!" Li Jie saluted Li Jiangtou at this time, and he didn't know many of the tools made of gunpowder, such as the rod scale, so it was better to let an experienced person like Li Jiangtou make the final preparation.

Li Craftsman was not polite, they had been staring at Li Jie's purification process just now, and at this time they also wanted to try the power of the gunpowder obtained after purification, so he immediately stepped forward, mixed the three materials according to the best ratio, and asked people to take a hollow iron ball, the gunpowder was poured into the iron ball and compacted, and the mouth was blocked after inserting the lead, this is the simplest firearm, called Thunderbolt, which is actually a cannon battle.

"Go to the proving ground!" Li Zhu immediately instructed, of course, the power of the firearms must be tested when they are ready, so the firearms also have a special test site, which is on the outskirts of the Firearms Bureau.

After the group came to the test site, Li Zhu took Li Jie and others to hide behind a low wall, and two thunderbolts were placed in the field, one of which was a thunderbolt made of purified gunpowder, and the other was the original old gunpowder, and the two thunderbolts were ignited at the same time.

I only heard the two loud noises of "boom~boom~", and there were also two puffs of smoke and dust in the venue, but it was obvious that the smoke and dust caused by the explosion of the purified thunderbolt were even louder, and even the sound was louder than the other.

Li Zhu and the others hurriedly ran forward, only to see that two pits had been blown out on the ground, among which the purified thunderbolt had blown up a pit that was more than two feet long, while the old thunderbolt had only blown out a pit more than a foot long, and the power was obviously very different.

"God! God! After this purification, the power of gunpowder has nearly doubled! Craftsman Li's face turned red with excitement.

"Li Gongzi is really a god, he can double the power of gunpowder, if this matter is reported, it will definitely be a great achievement!" The other craftsmen also reacted, and immediately praised Li Jie, although these craftsmen had a low status, they were still very confident in their craft, but they did not expect that Li Jie, such a young man, was more proficient in gunpowder than them.

"Congratulations to the bureau envoy for giving birth to a good son!" At this time, some smart people immediately congratulated Li Zhu, after all, Li Zhu was their top boss, and other people also congratulated Li Zhu when they heard it.

If someone else patted his ass, Li Zhu might not care, but when he heard so many people praising his son, he suddenly said it to Li Zhu's heart, and he immediately couldn't close his mouth happily.

Seeing the power of purifying gunpowder with their own eyes, these craftsmen no longer had any doubts, and immediately asked Li Jie for advice on the method of purification, although they had seen it with their own eyes, but some details still needed to be consulted by Li Jie, and Li Jie did not hide it, and explained the method of purification in detail, as well as some points that need to be paid attention to.

In the end, Li Jie also let the craftsmen operate it themselves, what are the irregularities, he also pointed out on the spot, which made Li Jie and others more appreciative of Li Jie, after all, a talented and approachable young man, especially if the other party is still the son of their boss, which is too rare for them.

Li Jie was busy working in firearms for most of the day, and he ate lunch with Li Jiangtou and them, and it was only in the afternoon that Li Jiangtou and them thoroughly mastered the technology of purification and wet gunpowder.

After doing all these things, Li Jie said goodbye and left, and accompanied Li Zhu to his official room, and when he entered the room, Li Jie immediately said: "Father, improving the preparation of gunpowder should be a great credit, right?" ”

"Of course, although the use of firearms in the army is limited, but the development is extremely fast, many generals attach great importance to firearms, especially last year in the battle of Dingbian, Xiping Hou broke 300,000 rebels in Yunnan with firearms, but also made the name of firearms shake the world, I heard that the DPRK and China even want to build a force equipped with firearms!" Li Zhu also looked very excited when he mentioned firearms, the Ordnance Bureau does not only make firearms, but he attaches great importance to firearms.

Li Jie knew that the so-called Xiping Marquis was the famous Mu Ying, that is, the founder of Yunnan Mu Wangfu, Mu Ying was Zhu Yuanzhang's righteous son, and he was good at using soldiers.

"Father, can this credit be sent to Your Majesty, so that Your Majesty can know the names of our father and son?" Mu Ying is not the focus of Li Jie's attention, what he is most concerned about now is whether he can use his credit to attract Zhu Yuanzhang's attention? It was also the second domino he had toppled in his plan.