Marin didn't care what the Genoese thought, he just explained the truth:

"My teacher had traveled to Port Kaffa and talked to the elders to find out the truth. However, while traveling in Asia, the teacher noticed a very strange phenomenon - although there were also recorded outbreaks of the Black Death in the region, they were not as frequent as ours. He then spent more than a decade in Persia and Turkey, and finally found the secret ......"

"What's the secret?" Everyone pricked up their ears in curiosity. Because the Black Death was more terrible than smallpox, it was very important to avoid it.

The teacher found that women in the Middle East are not allowed to go out because they are stuck at home, so many women like to keep cats with them. And these cats are not only the companions of those hostesses, but also the killers of rats, destroying the rats in the homes of those Middle Easterners......"

"Raising cats...... But isn't the cat the embodiment of an ominous? Emperor Maximilian I wondered.

"Here's the problem...... "Marin gave the emperor a thumbs up in his heart - a good compliment!

Marin explains:

"The teacher's research found that the reason why cats are considered ominous is because on spring nights, cats make terrifying and annoying calls when they are courting. In the silence of the night, this cry is indeed terrifying, like a devil. But in reality, it's just those cats who want to breed with the opposite sex......"

Speaking of this, many people present laughed...... This is the kind of topic that men have been excited about since ancient times......

Marin waved his hand and said:

"Don't laugh, I'm serious! This kind of cry is actually just a cat's normal courtship confession, similar to what humans say, 'Girl, I love you'......"

Everyone's laughter is louder, this topic is a bit exciting......

It's just that the cat's courtship sounds a little scary, and it's really a quiet night, so it's mistaken for a demon. However, as everyone knows, cats are active in the middle of the night, so there is no way. Dogs are also pets, but because they are mainly active during the day, although they also have sounds, they do not affect people's lives. At the end of the day, the cat's midnight bark is a bit out of place. And, it's just a little ugly......"

"But, Grand Duke Marin...... Oh no, Your Majesty Marin, what do you say have to do with the Black Death? The French envoy Duby asked.

Marin glanced at Dolby and explained:

"As I said earlier, the Black Death was called the plague, and it was spread by fleas on rats. If there are enough cats to eat all the mice, will there be no way for the Black Death to spread? ”

After listening to this, Dolby nodded and said:

"It seems to make sense...... However, can it be proven? ”

Marin shook his head and said:

"I can't prove it because it's too dangerous. After all, the Black Death was not the same as smallpox. If smallpox is planted with cowpox, it is not afraid of smallpox. However, after the Black Death patient survived, the next time he encountered the Black Death, it was still dangerous. Therefore, I don't dare to prove it indiscriminately. ”

Then, Marin said:

"However, what I want to tell you is that the North Sea Kingdom has been raising cats for a long time. Every granary in Beihai Country will have some cats to deal with rats that steal food. Therefore, our granary, food loss is smaller. Moreover, the elimination of rats also helped curb the spread of the Black Death. ”

"Everybody knows how dirty the bilges of a merchant ship are. On many merchant ships, there are a lot of rats living in the bottom warehouse. The Genoese merchant ships that returned from Kaffa brought rats with them, which led to the spread of the Black Death. ”

"Actually, the Black Death was so harmful in Europe because we misunderstood cats and expelled or even killed them. As a result, rats were infested and the spread of the Black Death became even more rampant. That's why tens of millions of people died in Europe because of the Black Death......"

The teacher's notes recorded that in some cities with many cats, the Black Death never broke out on its own initiative, unless it came from outside. The reason why Europe couldn't stop the Black Death before was because cats were expelled and rats were rampant, so the Black Death spread so quickly. ”

"So, in order to prevent the merchant ships from bringing back the plague from the outside world, I have decreed that every merchant ship sailing overseas must have a cat on board, specifically to deal with the rats on board, so as to prevent the Black Death from spreading again. Without rats, the Black Death would have no source of transmission. ”

"Of course, having a cat to kill a mouse is only the first step. In addition to eliminating rats, the teacher also advocated hygiene in his notes. For example, it is necessary to clean up all the feces in the city and transport them out of the city to prevent flies from breeding. The teacher recorded that not only rats were prone to breeding problems, but also flies that parasitized the feces that could be found everywhere in the city were also prone to plague ......"

"So you cleaned the cities of Beihai Country, collected all the feces and shipped them out of the city?" Maximilian I stepped forward in time at this time.

Marin nodded and said:

"That's right, that's it, flies are grown from maggots that live on feces, and their claws are full of unclean things like feces. If a fly bites the droppings that are everywhere in the city, then go and bite the white bread that you eat......"

Speaking of which, many people probably thought of something, and their faces were hard to look at...... Because, it's really likely......

Marin didn't care if they were disgusting or not, but continued:

"If a fly bites something that has a plague, then bite the food you eat, and if you eat this food, you will easily get sick and even produce plague ......"

Many people changed their faces, and it was Maximilian I who was "complimenting" again, and he hesitated:

"It's not that we don't want to do it, it's that if we start collecting manure as well, it's a lot of labor cost! If you keep the city clean, God knows how much it will cost......"

For His Majesty the famous Poor Ghost Emperor, money is the biggest problem......

Marin would love to show them that the manure could be pulled out and used as fertilizer, just like the Ming Dynasty had done. However, to do so is to cultivate competitors, and it is easy to cause food prices to collapse. Marin made a fortune from this, how could he tell the secret?

However, he did think of a solution:

"Ladies and gentlemen, don't you know that manure is piled up in a manure tank and can be used to collect nitrate and use it to refine saltpeter? Just build a nitrate collection center outside each city and dig multiple square pits to collect nitrate. The price of saltpeter is well known, and it is also in short supply, and this alone can recover the labor cost required to collect manure in the city......"

"That's a good idea......," the Emperor nodded, but asked again:

"Nitrate frost is generally in the cold weather, summer and warm weather such as late spring and early autumn, how to collect nitrate?"

At this time, the means of collecting soil nitrate are still very backward, and I only know that when the weather is cold, collect the frosted nitrate soil in the corner of the manure pit and scrape it down for refinement.

But they don't know that in later generations, they don't have to be so troublesome to collect soil nitrate, and they can directly mix urine with the soil for a natural reaction. Then, refine it directly. In this way, the proportion of saltpeter collected is also higher. The proportion of frosted nitrate in the corner of the wall is actually relatively low, and only part of the nitrate can be obtained.

But Marlin wouldn't tell them exactly how to extract nitrate, so he gave a suggestion:

"Well, if you have a city near the Rhine, and you can't extract nitrate in summer, late spring, and early autumn, then put it in barrels and ship it to the North Sea Country, and I'll buy it!" This way, you don't have to worry about not being able to recoup the labor cost of collecting manure when the weather is warm! ”

Marin has actually coveted the massive amount of manure in various countries for a long time, but unfortunately, he couldn't find a reason to buy it before. Moreover, it is easy to arouse suspicion in other countries. However, now he has found a reason......

"Do you have a way to collect nitrate when it's hot?" "Hello," Maximilian I asked, confused.

Marin had already taken a countermeasure, so he replied confidently:

"Yes, I've bought Iceland with Denmark, it's cold all year round, but it's not so cold that it freezes, and it's the best climate to collect nitrate. As long as the manure is loaded onto a ship and transported to Iceland for accumulation, a lot of soil nitrate will be scraped out in a few days. Also, there are not many people in Iceland, and they are not afraid that the island will be too dirty due to the pile of feces. Also, it's a bit cold and it's hard for flies to survive......"

When everyone heard it, they all thought it made sense. After all, everyone in Iceland has also heard of Iceland, saying that it is Iceland, but only the inland is colder, and the coast is still not frozen. This temperature, which is roughly equivalent to the kind of climate that frosts in the middle of the night in late autumn, is most suitable for seeping out nitrate, which is indeed very good.

But they didn't know that Marin actually wanted to cheat the fertilizer of various countries through this means. After all, compared to that bit of soil and frost, the fertility of manure is what Marlin values most.

Moreover, now Marin has no ability to make ammonia synthesis at all, and if he wants enough nitrogen fertilizer, he can only deceive the manure of other countries......

And the lie of using Iceland's climate to collect soil and frost seems to be flawless, so plausible that no one doubts it. Moreover, the North Sea Kingdom is indeed in great need of saltpeter. After all, the army of the North Sea State has a high proportion of firearms.

Therefore, while introducing the causes of the Black Death and how to prevent it, Marin, the new king, actually talked to the monarchs and envoys present about the business of collecting dung......

Marin repeatedly emphasized:

"Be sure to have damp feces with urine, not dry feces!" The reason for this emphasis is that most of the saltpeter cost is generated in urine, not fecal lumps. He was afraid that the dung sold by various countries would be too real, so he dried it and sold it to him.

To this end, Marin also offered to provide sealed dung buckets for them to use to hold damp poop......

As for the purchase price, it is about the amount of labor required to collect the manure in those cities. The labor cost in Germany is only 2 fennig per day, so you don't need to give much.

The monarchs and the great nobles didn't care about the money, as long as they didn't have to pay the wages of the workers who collected the dung.

In this way, a good scientific lecture on how to deal with the Black Death was distorted by Marin, a lewd second goods, and turned into a meeting site for collecting dung......

"The king collects dung", Marin is famous. This meme was later used by Europeans for hundreds of years......