Speaking of rubber substitutes, Li Su immediately thought of one thing, when he made his first bicycle in Chang'an, the craftsmen in Fuzhong used to coat the wheels with a special tree gum, which seemed to be very wear-resistant, maybe it was feasible?

Thinking of this, Li Su hurriedly asked people to call the two stewards in the house, Huang Cheng and Lao Wu Tou, these two people turned out to be the craftsmen of the woodsmith and ironware workshop in his house, because they helped Li Su make a lot of new things, so they were promoted to stewards, and the bicycle was also successfully developed under the leadership of the two of them.

Yifan didn't know what Li Su called the two stewards to do, and looked at Li Su a little strangely. After a while, Huang Cheng and the old Wu Tou rushed over, and when they saw Li Su, they immediately saluted: "The villain sees the prince!" ”

"Get up, when the king asked you to make that bicycle, you coated the wheels with a thick layer of glue, which seems to be very tough, is there still it in the house now?" Li Su asked the two of them to get up, and asked impatiently.

As soon as Li Su asked about this, both of them were stunned, this time the more talkative old Wu Tou did not speak, but looked at Huang Cheng, who was very wooden, because that kind of glue was made by Huang Cheng.

"Your Royal Highness, that kind of glue was originally discovered by the villain, but this kind of glue is not very sticky, and its use in wood is limited. Huang Cheng hesitated for a moment, and then replied honestly.

"Oh? Why is that? Li Su was very strange when he heard it.

"Your Highness, that kind of glue is made by the villain from the sap of a fruit tree, but that kind of fruit tree has just been spread to my Datang not long ago, and it is only planted around Chang'an. This time I came to Dengzhou, although the villain also brought some seeds, but it was only planted for a year, and there was no way to get the sap at all. Huang Cheng said helplessly.

Tree sap, how does it sound so much like a rubber tree. But Huang Cheng clearly said that it was a fruit tree, but in Li Su's memory, the rubber tree didn't seem to produce any fruit?

"What's the name of that fruit tree, and what are its characteristics?" Li Su hurriedly asked, the rubber tree is still far away on the American continent. It was impossible to spread to the Tang Dynasty, so Li Su quickly denied the speculation of the rubber tree.

"Your Royal Highness, the villain heard that the fruit tree was brought by Hu Shang in the West, and I don't know what the name was, but after it was passed on to my Tang Dynasty, because the fruit was as sweet as honey, it was called honey fruit. In addition, this fruit is very strange, it does not bloom and bears fruit, so some people call it figs! Huang Cheng bowed down and replied again.

"Oh, it's a fig!" After Huang Cheng said this, Li Su immediately remembered. When he was in Chang'an, he usually ate a lot, but he didn't care about it at the time, after all, figs were also very common in his later life, and there was no fuss at all, but he didn't expect it. This thing turned out to have just come from the Tang Dynasty.

"Your Highness, we have planted a lot of fig trees in Chang'an's mansion. Presumably, His Royal Highness has also tasted figs, and if there is a need, I am afraid that it will have to be transported from Chang'an, but this time, almost two months have passed! Huang Cheng replied honestly.

In fact, Huang Cheng didn't know that since Li Su dedicated the bicycle to Li Shimin. Huang Cheng's method of making gum was also presented, and the bicycle was imitated by the supervisor. With the promotion of bicycles, the demand for gum on wheels has naturally increased significantly, and now many people in Chang'an City have begun to plant fig trees in large quantities, but the time is too short to take the sap at all. In this way, the ripe fig trees are even more precious, and the ones planted in Li Su's mansion have been purchased at a high price by the general supervisor, and the trees have been removed, but this matter is too small, and Li Su and Huang Cheng, who are far away in Dengzhou, do not know at all.

"Okay, then you set off immediately, rush to Chang'an immediately, and make that kind of gum as soon as possible, and the more the better, if it's not enough, let Mr. Wang help you find a way!" Li Su immediately commanded. Mr. Wang is also Wang Zihao, Xijun has entered his mansion, and Wang Zihao has become his elder, and it is not very respectful to call him by his name, so he changed his name to Mr. Wang, and everyone in the house knows it.

"The villain obeys!" Huang Cheng also knew that His Royal Highness was going back to Chang'an, but now he let himself go first, obviously this matter was very important, so he didn't dare to slack off, and immediately went back to the house to prepare, and left Dengzhou without even eating lunch.

"Rokuro, didn't you say you were looking for rubber, why are you looking for any figs?" Yifan asked with a puzzled face at this time, in fact, she wanted to ask just now, but she couldn't interject.

"The rubber thing is good, but we Datang can't find it at all, so we can only retreat and try it with that kind of glue made of figs, but it should be about the same." When Li Su said this, he seemed very unconfident. In fact, he did not know that figs and rubber trees are trees of the same family, and rubber can also be made from the sap produced by itself, of course, the yield is not as large as that of rubber trees. As for the kind of glue made by Huang Cheng, the composition in it is almost the same as rubber.

Putting aside the problem of sealing the steam engine for the time being, Li Su carefully observed the operation of the steam engine, and discussed with Yifan the shortcomings and areas for improvement. In fact, the reason why the horsepower of this steam engine is so small, in addition to the reason for air leakage, there are also many problems in the design, which is not to say that the ability of a sail is a problem, but when it was originally designed, it was only to make it run continuously, as long as this basic requirement is achieved, the horsepower can be improved step by step on this basis.

For this, Yifan has begun to work on the design of a new steam engine after making a prototype of this steam engine, the purpose is to improve the power of the steam engine, with this prototype foundation, I believe that the new steam engine will soon be able to complete the design, but limited by the process and sealing problems, even if the power is increased, it is estimated to be very limited.

The process can not be improved in a while, and for this point Li Su this layman can not help at all, the only thing that can be solved is the problem of air leakage, as long as the sealing material can be found, I believe that it will definitely increase the power of the steam engine a lot, although there is still a great waste, but the practicality is definitely no problem. At least not like the prototype in front of them, which can only be used as an ornament.

Thinking of this, Li Su was even more determined to solve the problem of air leakage, if the kind of glue made by Huang Cheng still didn't work, then he would publish the map of the American continent to Asia, and then offer a sky-high reward, I believe that there will be brave men under the heavy reward, and someone must dare to take a big risk, although the hope of success is very slim.

After watching the steam engine, Li Su spent half a day in the Academy of Sciences, went to other groups to see their progress, and helped if he could think of it, of course, Li Su's level is completely that kind of second-hand, and there is really not much help that can be helped. It wasn't until noon that he went back to the house to accompany Wen Xin and them to dinner, but he had to go out in the afternoon because Wu Meiniang wanted to see him.

Wu Meiniang still lives in the house arranged by Li Su for her, although Li Su has long let go of the control of her freedom, but in order to avoid unnecessary trouble, Wu Meiniang has always lived in a simple house, if it is not necessary, she basically does not go out much, even if she goes out, she will dress up, and she will also call Yang Shi and his wife.

I haven't seen her for a few months, and Wu Meiniang naturally misses Li Su very much, so she also deliberately cooked herself, made a few authentic Guanzhong dishes, warmed a pot of light wine, and sat at the table very obediently waiting for Li Su.

Li Su pushed open the door and saw the scene in front of him, especially Wu Meiniang wearing regular clothes, sitting on the chair with a lazy face, seeing him come in, he smiled slightly, and said lightly: "Husband, are you back?" ”

I haven't seen her for a few months, but Wu Meiniang is even more charming and moving, especially because of the hot weather, she is wearing relatively thin, and her bumpy figure is displayed, which makes people can't take their eyes off it at first sight. Wu Meiniang is a year younger than Wen Xin, but the advantage in figure is not a little bit stronger than her, but this is innate, no matter how hard she tries, she can't learn it.

Li Su looked at her well-behaved appearance, she was a distressing little wife, and a little tenderness surged in her heart at the moment. In fact, Li Yu didn't have too many thoughts about Wu Meiniang at first, but after getting along for a while, he suddenly found that the other party had actually broken into his heart a long time ago, especially in the past few months of separation, in addition to missing Wenxin and cherishing Jun, what he missed most was Wu Meiniang in front of him.

"Mei Niang, you've worked hard for this time!" Li Su stepped forward quickly, picked up Wu Meiniang from the chair, and put it on his lap, and then said softly. During this time, he was far away in Goguryeo, and all matters related to intelligence were taken over by Wu Meiniang, which made the burden on her body a lot heavier all of a sudden, so Li Suhui said so.

"Hehe, no matter how hard Mei Niang is, she can't compare to the hard work of her husband on the battlefield and killing the enemy for the country!" Wu Meiniang smiled mischievously. She knew that Li Su was just a foil when she went to the battlefield, but she still said this, obviously joking with Li Su.

"Of course, the husband is very heroic on the battlefield, Li Ji and Niu Jinda, the two big managers, are very powerful, but they were blocked by a small Anshi City, and in the end, it was not the husband I rushed there, and I took the Anshi City at once, and even the city lord was blown up, and the Goguryeo king ......"

Li Su naturally heard that Mei Niang was joking with herself, but his cheeks were already thick to a certain extent, and he immediately followed her words and began to brag about his heroic posture on the battlefield, and told his experience on the battlefield by bragging.