Chapter 495 Unexpected Encounter

When it comes to the preparation of gunpowder, we have to mention saltpeter, which accounts for a very large percentage.

Saltpeter often contains sodium nitrate and potassium nitrate. Both of them have the property of absorbing heat when dissolved in water, and can even cause water to freeze. Therefore, saltpeter was also used as a refrigerant in ancient times.

Of course, compared to refrigeration, in Yuan Xi's opinion, what can make saltpeter more useful is obviously heating, which is the art of explosion.

However, what is needed to make gunpowder is potassium nitrate, not sodium nitrate, because the latter easily absorbs water, which can make the gunpowder damp, seriously affecting the explosion effect or even causing it to misfire. Therefore, products mixed with multiple nitrates can only be used as fireworks most of the time.

However, to purify it, it involves two methods of making gunpowder saltpeter. One is to convert sodium nitrate into potassium nitrate through chemical reaction, and the other is to filter out potassium nitrate from the mixture of sodium nitrate and potassium nitrate to purify potassium nitrate.

The simplest and most direct source of saltpeter is saltpeter soil.

Nitrates are generally soluble in water, so they are difficult to find in areas with abundant rainfall in summer and autumn. However, in the cold and dry northern regions in spring and autumn, due to the sudden change in temperature, nitrates will crystallize and precipitate, commonly known as alkali.

The place where these things appear is often the toilet. This is because the urine excreted by humans and animals is rich in urea, which slowly reacts with water to decompose into ammonia and carbon dioxide. Under the action of ammonia bacteria and nitrate bacteria, it undergoes a series of chemical reactions to generate nitrite and nitric acid, and finally sodium and potassium ions in the surrounding environment to generate nitrates. This process is commonly known as urine cocoon.

In medieval Europe, due to the lack of saltpeter mines, saltpeter soil in toilets became almost the only channel for preparing gunpowder, so urine was listed as a war preparedness resource by the royal families of various countries at that time.

Because it is easiest to collect urine in places where people gather, King Charles I of England once issued a regulation requiring monks to encourage people to urinate on the church benches when they came to church for worship.

Because people were not allowed to leave the pews during worship, a large amount of saltpeter could be collected through this practice. From then on, church pews became an important source of munitions for Britain's foreign expansion.

After obtaining the saltpeter, it must be purified. If there are too many impurities, even with the best gunpowder ratio, the effect cannot be achieved. This is Yuan Xi's biggest headache.

Throughout Chinese history, the proportions of gunpowder have been constantly changing. This was certainly due to its improvement during use, but the impurities in saltpeter were also an important factor restricting its development.

The process of purifying saltpeter is called boiling alkali and saltpeter. During this process, the Chinese people discovered another key raw material.

plant ash.

Its main ingredient is potassium carbonate, which is used to provide potassium ions. By continuously adding wood ash, then dissolving it in water and heating it, and finally filtering it, the calcium, magnesium ions and carbonate ions in the aqueous solution can be effectively removed, leaving only potassium carbonate and sodium carbonate.

After a series of steps, the purity of potassium nitrate can be improved, thereby helping the gunpowder to reach the final ratio.

The reason why gunpowder is one of the four great inventions is that it condenses a lot of experience and wisdom of the Chinese people. It is really not easy to achieve this without the assistance of basic chemical knowledge.

Saltpeter soil cannot be collected for mass production, but the potassium-rich brine in the Black Mountain Salt Lake is abundant and sufficient. Moreover, using it to boil saltpeter can not only produce crude salt and pure saltpeter, but also produce brine, which can not only be used to make tofu but also increase soil fertility. It can be said to kill three birds with one stone.

Therefore, taking over Montenegro means far more to Yuan Xi than people of this era think, but people may not realize this for quite a long period of time.

He looked at the last few bamboo tubes left on the table, reached out to take them and put them on his waist. Seeing that Lu Lingqi also wanted to take them, he said, "This thing is very dangerous. Are you sure?"

Lu Lingqi said disdainfully: "Isn't it just the fireworks that Master set off back then?"

Yuan Xi said: "Although it has not been tested many times, the power this time may be much greater."

"Really?" Lu Lingqi was eager to try, "Click and see!"

Yuan Xi was helpless, "This thing is not easy to use. It is used to break through the armored soldiers and cavalry formations."

He explained the method of use in detail, saying: "After lighting it, you must throw it out within ten breaths, otherwise it will injure your hand. If it explodes in your own formation, it will be more trouble than help."

After hearing this, Lu Lingqi waved her hand and said, "I understand, don't worry." Then she stuffed the two bamboo tubes into her waist.

Seeing her nonchalant look, Yuan Xi thought to himself that this made him even more worried.

The two men walked out of the tent side by side and found that everyone was already lined up and ready to go.

The number of people was much larger than what he brought. This was a temporarily disbanded team that mixed in with the reserve forces of several cities around Haixi, because this time facing the situation of a large army approaching, a few thousand people were too few.

But with the influx of new recruits, in the worst case scenario, the combat effectiveness may not increase but decrease. Then it will all depend on their performance in battle!

Yuan Xi took a deep breath and raised his hands high, "Move camp!"

A day later, more than 200 miles east of Haixi, Yuan Xi's army encountered tens of thousands of refugees from Xuzhou.

Chasing closely behind them were the vanguard cavalry of Cao's army, disguised as Taishan bandits.

The moment the two armies encountered each other, neither side hesitated, and they immediately sped up their horses and charged towards each other!

At this point, both sides no longer concealed their concerns. They both knew each other's intentions, and there was only one choice.

A life-and-death struggle!

The two sides first fired a few rounds of arrows and rushed from a distance of hundreds of steps to a distance of dozens of steps.

The leader Cao Chun instinctively felt that something was wrong. Although this was his first time fighting against the Youzhou soldiers, he had fought many battles with Lu Bu in Yanzhou with his cavalry before. It can be said that he was familiar with dealing with cavalry.

But after several rounds of shooting between the two sides, Cao Chun keenly discovered that the opponent's body was extremely stable when shooting, and his shooting speed was faster, and thus more accurate!

Judging from the number of people killed on both sides, he realized that his side was at a disadvantage as soon as they met!

Seeing that the two sides were about to collide with each other in just a few dozen steps, the soldiers on both sides had already put away their bows and drawn the ring-handled swords at their waists, ready to engage in battle the next moment!

Cao Chun looked at the opponent's armor, which was obviously much more sophisticated than his own, and had a bad feeling in his heart. The opponent's posture seemed a bit incongruous no matter how he looked at it!

His body trembled. The two sides engaged in battle, each holding a weapon in one hand and holding the saddle with the other, but the other side held the knife with both hands? ?

He yelled, "Change direction!"

After hearing this, the Cao cavalry in front quickly turned their horses' heads in an attempt to avoid the Youzhou army's frontal attack, but it was already too late!

The dozens of riders in front dodged, but the hundreds of riders behind couldn't stop their momentum and rushed towards the enemy.

They were also brave. They roared loudly, shook their arms, and swung out with their ring-handled swords!

This is the most effective way to kill the enemy on horseback with a ring-handled sword. By using the whip-like posture of the arm, the force of the chop can be increased to the greatest extent. Coupled with the horse's sprinting speed, if it hits the opponent's body, even if it cannot break the armor, it can still cause serious internal injuries to the opponent!

The sound of sharp and tooth-grinding collisions of weapons and armor rang out frequently, accompanied by screams and groans, echoing across the battlefield.

People from both sides kept falling off their horses, but Cao Chun was surprised to find that not only did the number of Cao's soldiers falling off their horses far exceed that of the other side, but almost all of them had no reaction after falling off their horses, while the other side could still get up!

He made a prompt decision and shouted, "Turn around, disperse!"

The Cao army cavalry immediately distanced themselves, turned around and fired two rounds of arrows, then gathered along the way they came, and finally, under the leadership of Cao Chun, rode away.

After Yuan Xi received the news of the conflict between the two sides, he learned that in this first battle, there were more than a hundred cavalrymen on both sides, and more than a dozen of his own people were killed or wounded, while more than half of Cao's troops were killed or wounded, but he was not happy at all.

Horse stirrups are used here, and the weapons and armor are also the best. In a head-on collision, this is all we can do.

Although he knew that Cao's army must be more distressed than himself, it seemed that the number of cavalry on both sides could not determine the final outcome of the battlefield. The main force of the decisive battle between the two sides was still the infantry.

Yuan Xi has already learned that Cao Cao has transferred almost all of his most powerful Qingzhou troops to Xuzhou!

Although the Qingzhou soldiers' equipment is average, they were originally Yellow Turban bandits and have rich combat experience. Therefore, they are extremely difficult to deal with on the battlefield. Just look at the many times Lu Bu suffered defeats.

At that time, Lu Bu had eight strong generals under his command, including Zhang Liao and Gao Shun, but he was still defeated several times in battles with Cao Cao. On the one hand, this shows that Cao Cao's tactics were correct, and on the other hand, it also shows that the combat effectiveness of the Qingzhou soldiers should not be underestimated.

Now the other side has an overwhelming advantage in numbers. If Yuan Xi does not have a way to break the deadlock, he will most likely be surrounded and killed by the enemy.

Yuan Xi learned another bad news from the refugees in Xuzhou.

When Liu Bei was the rear guard, his entire army was defeated in a surprise attack by Cao's army that night and his whereabouts are unknown.

Yuan Xi's heart tightened. Was Liu Bei probably dead?

Although he understood that if Liu Bei died, it might not be a bad thing for him, maybe Guan Yu and Zhang Fei would come to him for revenge?

But it seems that in later generations, Liu Bei was defeated by Cao Cao and disappeared, while Guan Yu was captured and surrendered to Cao Cao. Who can tell clearly about what is happening in this world?

He said to Lu Xun: "Let the soldiers set up camps and dig trenches on the spot to build fortifications."

After hearing this, Lu Xun hurried out to make arrangements. Soon, the soldiers began to cut wood and dig on the spot, and set up chevaux de frise and other equipment.

Facing an enemy that is several times larger than your own, there are two ways to deal with it. One is to use mobility to erode the enemy's weak military force, and the other is to set up a stronghold for defense.

According to Yuan Xi's situation, it would be more flexible to take the former approach. However, he had to buy time for the fleeing people of Xuzhou, so he could only hastily build a defensive offensive to guard against the attack of Cao Cao's main force in an hour or two at most.

As Yuan Xi expected, as the people continued to flee to the rear, the Cao army in the telescope continued to gather, and it seemed that they were preparing to form a battle array and march.

On Yuan Xi's side, there were only a few thousand soldiers and a simple camp with only a hundred or so trees.

Just as Yuan Xi was preparing to respond to the local attack, a spy brought news that Liu Bei's family members were surrounded by Cao's army a dozen miles to the south.

When Lu Xun heard this, he immediately said to Yuan Xi: "Your Excellency, do not act rashly. This is a trap."