The next week was obviously a busy seven days, the hardest one of the national polo team was Liu Wuzhou, the remaining 26 members of the team were only training for one hour each in the morning and afternoon, Liu Wuzhou exceeded six hours of practice time for seven consecutive days, and he also knew the truth that "diligence can make up for clumsiness".

There was a rain in seven days, and after the rain, it officially entered the height of summer, and the weather became hotter and hotter every day.

Yang Guang and Baiguan were in full swing in this hot weather preparing for various matters related to the Northern Tour.

On May 15, Yang Guang officially left the Eastern Capital.

But this departure seemed thunderous and rainy, Yang Guang did not pass through the city in the limelight, but quietly left the city at the usual early court time, and after gathering 200,000 troops, he went directly to the next stop.

The farther north the procession goes, the closer it seems that the sun is from the ground. Yang Guang sat in a special carriage, although it did not feel bumpy, but the road was dusty and difficult; His entourage complained more in a low voice, the comfort of this trip was really different from that of the day when he went to Jiangdu.

"Zitong, you have suffered." Yang Guang looked at Xiao Biluo, who was wiping his sweat with a towel from time to time, and said with a smile.

"If you can be with Your Majesty, why should the concubines have any trouble? However, it seems that all the ministers did not understand the true meaning of His Majesty's trip. Xiao Biluo shook her head, most of what she said was from her heart, what is the point of being able to stay with the man she loves?

"There is a saying that 'the ass determines the head', and those who have nothing to do can only see that I have enslaved millions of laborers to dig rivers and build roads, but how can they understand that my original intention is to communicate between the north and the south, in order to achieve the true reunification of the north and the south?" Listening to Xiao Biluo's words, Yang Guang nodded at first, and then shook his head bitterly at the nonsense of the idlers.

"Your Majesty's words are not necessarily true. Perhaps it was because they understood His Majesty's original meaning that they would say something against it. For example, on the same day, His Majesty wanted to move the capital to Luoyang, and the Guanlong forces opposed it vigorously, the reason for this was that they were afraid that their vested interests would be impacted, and they were afraid that they would lose control of the court; His Majesty's frequent conscription of labor naturally gave the villains an excuse to attack. Xiao Biluo nodded, she didn't know much about national affairs, but she could feel the pressure from all sides after Yang Guang ascended the throne.

"When the Khitan Kouying Prefecture was in the day, I decided to tour the north, but I was in Jiangdu at the time, and I didn't expect that after returning to the eastern capital, I would be riddled with mundane things, and this delay would be another year. In the past year and a half, there has been a surge of power outside the Great Wall, especially the Goryeo ......"

When Yang Guang said Goryeo, he couldn't help but think of the war between the two countries more than ten years ago, and if the Great Sui had subjugated Goryeo, Yang Guang's trip to Zhuojun might not have been much necessary.

"His Majesty has the heart to conquer Goryeo, and the concubines can understand it; Goryeo's wolf ambitions are well known, but Goryeo's national strength is stronger than that of Linyi and Khitan. Xiao Biluo nodded, she knew Yang Guang's temperament, and then cited the conquest of Linyi and the defeat of the Khitan.

The battle of conquering Linyi was only half a year from the preparation to the triumph, but after the great victory, the Great Sui was injured by 1,000 enemies and lost 800 of them, and what is even more unacceptable is that five or six out of ten soldiers who died died of water and soil adaptation.

As for the Khitan, it was all because Wei Yunqi took Yang Guang's gold medal that day to go to the Turks to borrow troops, and it was regarded as defeating the Turks with the strength of the Great Sui alone.

What about Goryeo? Gao Li is obviously not a soft persimmon, otherwise Yang Liang would not have been able to attack it for a long time.

"I have my own measure. I plan to dig a canal from Zhuozhou to the eastern capital within three years, as long as there is a canal, it will no longer be a problem to transport troops and grain; If there is such a canal, why should you and I suffer from this bump? ”

Yang Guang laughed, obviously thinking that Xiao Biluo had taken a look at Gao Ligao, in fact, the current Yiqiē was still under his control.

"Dig a canal? Please think twice! When Xiao Biluo heard Yang Guang mention digging a canal connecting Zhuojun and the Eastern Capital, he was a little shocked; Starting from the repair of the eastern capital, and then digging the canal to build the granary, the labor used in recent years is really a lot; Now, for the northern tour, hundreds of thousands of laborers in Shandong and Shanxi have been used again, although some are hired by merchants, but now is the time when the wheat is ripe.

If you dig a canal again......

Xiao Biluo didn't dare to imagine that such frequent and large-scale conscription of labor was a move to shake the country's foundation; Yang Guang is indeed a little anxious, there will be many, many things that need to be done to achieve his great cause, but it is impossible for a person to become a fat man in one bite.

Zitong is relieved. The Great Sui and Goryeo are now in vain, and it will be at least three or five years before they tear their faces and enter a hostile state, and I have been preparing for them in the past few years. ”

Yang Guang no longer talked about the canal, and Xiao Biluo lost no time in picking up a bright red cherry the size of a little thumb and gently putting it in her mouth, but at this time, the carriage was a meal, and the cherry almost fell from her hand.

"Qi Bing, there is a horse pulling a cart that is tired because the weather is too hot." Yang Guangzheng wanted to ask why the carriage stopped, and went to listen to a guard outside the curtain report the situation loudly.

"Then rest in place!" Yang Guang immediately gave the order and picked up a piece of watermelon on the table, but the watermelon that had been roasted by the sun for a long time tasted really bad, if it weren't for this melon following him all the way, maybe the bite he just ate would have been spit out, but now he has eaten the whole piece.

"Wang Yi, take these cold melons down and let people eat them! Ten for my polo team! Yang Guang knew the truth that "it is better to be happy alone than to be happy", and immediately gave the watermelon he didn't like to eat to the rest of his entourage.

"This ...... If this cold melon is chilled, it will be cool! Pei Yuanqing looked at the melon that had been cut, but when he found that everyone had no desire, he couldn't help muttering, this thing really doesn't taste good after being exposed to the sun, but this cold melon was given by the emperor, even if you don't like to eat it, you can't throw it away.

"Who's to say it isn't? But where is there any ice on the road? You think this is the Eastern Capital! Cheng Yanjin pursed his lips.

At this time, it is the height of summer, and it is indeed an incomparably luxurious thing to eat chilled cold melon, even if it is an emperor.

As early as the Shang Dynasty, China had the custom of hiding ice cubes in the winter and taking them in the ice cellar in the summer. The government of the Zhou Dynasty had officials who specialized in managing this matter, called "Ling Ren", and built "ice wells" for ice cellars. Regarding this, it is recorded in the Book of Songs, Wei Zhi, and Song Dynasty Huiyao.

In the northern region, the ice is hidden in winter, and the following year is taken out in the summer, and the government gives it to the ministers, which is called "awarding ice" and "giving ice", which is an important part of the ancient government decree. Later, large households in the central and northern parts of the capital also built cellars to store ice for the next summer, so it is not difficult to drink a glass of chilled Sanle pulp in the eastern capital in summer, and if you want to eat chilled cold melon, you can only spend a little more money.

But now, Su You and the others are on their way to Zhuojun, and it is not easy for them to even fetch water in the place where they stay, let alone ice?

"Ice? Ice making? Su You muttered a few words, and then nodded.

"What are you laughing at, sir?" Cheng Yanjin looked at the weird smile on Su You's face, and thought that he had caused his dissatisfaction by ridiculing Pei Yuanqing just now, and then used his questions to arouse everyone's attention.

"Didn't you just want ice? Maybe I have a solution. Biting gold, you go to the accompanying doctor to find some saltpeter, the more the better. Su You nodded, and then wrote the word "nitrate" on the ground with a branch.

The method that Su You thought of was naturally "making ice with saltpeter" in chemistry, when saltpeter dissolved, it needed to absorb a lot of heat, enough to make water condense into ice, this is really what Su You did in chemistry class in high school, so he was also very sure at the moment.

After Cheng Biting Jin went, Su You first prepared two bowls, large and small, the big hand was for dissolving saltpeter, and the small bowl was of course the target, that is, the ice vessel obtained after the successful experiment.

"This is saltpeter?" Su You poured half of the nitrate that Cheng Biting Jin had begged for into the big hand filled with water, but there was no reaction when he opened the lid.

"It's manganese!" Su You suddenly realized that the main ingredient of saltpeter is potassium nitrate, and the main ingredient of miscanthus is sodium sulfate, both of which are of great use in traditional Chinese medicine, but the role of miscanthus nitrate is more extensive, and it is obvious that now he is self-defeating.

In fact, saltpeter was mined in the production of gunpowder until the end of the Tang Dynasty, that is, nearly two hundred years later. It was also the people of the Tang Dynasty who discovered that saltpeter dissolved in water would absorb a lot of heat and cool the water to freeze, so that there was a method of making ice in summer.

Subsequently, clever traders gradually added sugar to ice to attract customers; In the Song Dynasty, there were more and more varieties of cold food in the market, and merchants also added fruit or juice to it, and even added fruit pulp and milk to the ice, which is very similar to modern ice cream, in other words, this is the ancestor of modern ice cream and even Häagen-Dazs.

In the 13th century, Marco Polo brought the ice cream method back to Italy and then to France. On this basis, one of Queen Catlin's personal chefs developed and engraved a semi-solid ice cream with cream, milk, and spices, which became popular with the aristocracy and quickly spread to the current wide range of ice creams. But in any case, without the "ice cheese" of the Song Dynasty, there would be no Häagen-Dazs today.

Su You wanted to be called the originator of "ice making", but he encountered a small setback due to the misuse of materials, but finding saltpeter was not difficult for Su You, because their next stop was Zhuojun.

The ruins of Zhuojun are not too far from the later Beijing, and Su You happened to have studied in Beijing for four years, or Su You was in Beijing for four years. In four years, Su You did not do anything vigorous and earth-shattering, but he can say that he traveled to hundreds of historical monuments and natural scenes around Beijing.

Coincidentally, Su You still remembers that there was a cave where a large amount of saltpeter was exposed, and that place was not far from Zhuo County.

"How can I suddenly discover a saltpeter mine without letting people know that I have been in Zhuo County for a long time?" When Su You was looking for the possibility of such a new thing as "ice making" appearing out of thin air, Yang Guang's northern patrol team had already walked to the outpost of Zhuo County.

Zhuo County's Taishou Cui Hongsheng and the county Cheng Xue Shixiong and others also arrived on the outskirts of the city early.

Cui Hongsheng and his brother Cui Hongdu were knighted with military merits; Later, Cui Hongdu's daughter married Yang Yong, and after Yang Yong was convicted, the two brothers were dismissed because of joint sitting, and then Cui Hongdu passed away, and Yang Guangyin accidentally enabled Cui Hongsheng......