In the morning, Lin Bei took a bath in Longtan.

Now the water in Longtan is not only exclusive to Lin Bei, but also likes water, in addition to predation, it soaks in water almost all day and night.

Red Jiao is not like Lin Bei, not picky eaters at all, don't look at the size is not small, frogs, rodents and birds can eat, just like last night, this guy caught a total of several fat toads, and ran out to catch a few mountain mice, and every time he will throw food to Lin Bei first, let Lin Bei eat first, but unfortunately Lin Bei can only thank him for this kindness, but he will definitely not dare to eat it.

Cui Lan and the others also woke up, and went to the waterhole to wash as usual, and then the red Jiaoren stood up and began to attack, and Lin Bei had to appease this irascible guy again.

"Adult, don't you know about people?" Cui Lan looked at Chijiao and asked.

Lin Bei nodded, hoping that the hunters would stay away from Chijiao, without Lin Bei's presence, Chijiao would definitely attack people, its temper was as hot as its color.

"Oh." Cui Lan nodded in understanding, thinking that she would have to tell the hunters to stay away from this little adult.

Today should be the last time to capture elephants, there are still five elephants left in the Elephant Valley, as long as you go again, you can catch them today, and when the hunters finish washing, Lin Bei first asked the hunters to rush to the school, and he has to find a nest for Chijiao.

Chijiao has no wisdom, and his aggression is quite large, and there are still a lot of people from Lin Bei, such as Bian Fuzi and An Zhongzhi, they don't know about Chijiao, in case Lin Bei goes out to catch an elephant, it will be bad if the two come back and run into Chijiao, so Lin Bei is ready to let Chijiao hide in the taro field.

Although he can't communicate with words, but his actions can, Lin Bei pushed Chijiao into the taro field, if Chijiao wanted to climb out, then Lin Bei pushed it again, and so on, Chijiao seemed to understand what Lin Bei meant, his body curled up for a while, and he retracted into the mud below, only revealing a head, looking at Lin Bei motionlessly.

Lin Bei said that he was very satisfied, it seems that Chijiao is not as stupid as he imagined, this is a good thing, Lin Bei is afraid that Chijiao is a flurry head.

In order to verify whether Chijiao really understood thoroughly, Lin Bei deliberately went out for a while, hid in the distance and secretly looked, Chijiao was motionless for a long, long time, Lin Bei was completely relieved and went to the school.

As soon as she arrived at the school, Feng Niangzi came over, first saluted Lin Bei, and then said, "My lord, the shopkeeper of Zhen's firm sent someone to send the iron pipe over, where to put it in the biogas digester." ”

Lin Beida was overjoyed and hurriedly rushed over, only to see a few craftsmen studying the iron pipes ordered by Lin Bei.

The iron pipe is divided into two parts, one part is a hollow pipe and the other is an iron stopper.

In fact, the craftsmanship of ancient craftsmen should not be underestimated, like this biogas pipe Lin Bei thinks that it is very good, the surface of the iron plug does not know what is wrapped, it is relatively soft, it can be stuffed into the iron pipe, and the sealing ability is quite good, because the craftsman tried to put it into the water and blow on the other side, there will be no bubbles.

"But it's still a pity that this is not a valve." Lin Bei still has some regrets, and at the same time is a little worried, if there is too much biogas in the biogas digester, will the plug be stuffed in this way, will it lead to the explosion of the iron pipe? Lin Bei was going to wait for Bian Fuzi to come back, and let Bian Fuzi tell the craftsmen about the idea of the valve, and let them improve it, the craftsman should be able to improve, after all, the technical content of the valve is very simple, you can use a screwed valve, or you can use a valve that moves left and right.

When Lin Bei came back from Elephant Valley, another good news came, the bison skin had been sewn up.

The sewn bison leather bag was quite large and needed to be carried by several people, and the iron pipe had been sewn onto the cowhide bag.

"Blow in, and see if it leaks."

A man came out, puffed out his cheeks and blew into the cowhide bag, blowing so that his face was red and his neck was thick, and at last he poured a little gas into the bag, and then everyone carried it and threw it into the river.

Several men jumped down, first standing still, and then squeezing the cowhide bag vigorously as instructed by the craftsman to see where the air would leak.

As soon as it was squeezed, the effect naturally came out, and there were air leaks in several places, and the places connected to the iron pipes were also leaking, and the bubbles bubbled up, and they were written down by the craftsmen one by one.

"It seems like the interface is leaking." A craftsman said.

Because it is sewn up by several cowhides, it is indeed easy to leak air at the interface, Lin Bei was also anxious to see it on the side, and wanted to ask what kind of cowhide bags they were sewn with, but unfortunately no one could translate it, so he could only do it.

"Why don't you sew two more layers of cowhide at the joint?" There are craftsmen who mention yì road.

"Or let's concoct it first, the cowhide will shrink a little after processing, maybe it will cover the air leakage?"

The craftsmen agreed on this method, so they opened the leather bag and began to concoct it.

Lin Beishang is the first time to see the ancient people concoct things, the method of concocting is also called bubble burning, as the name suggests, it is the method of steaming and roasting, which is very simple but very practical.

The craftsmen first threw the cowhide into the warm water and soaked it slightly, the warm water will melt, which will make the cowhide become loose, and then scoop it up, quickly smear it with grease, and then put it on the fire and smoke it slightly over a small fire, the loose cowhide will shrink under the action of the fire, so that the oil will also melt into the cowhide, so many times, the cowhide soaked in oil becomes extremely tough, and finally it can even reach the point where the knife is not bad, and because of a lot of oil, so the resistance to decay is quite strong.

Of course, this is all what Lin Bei saw, as for what he couldn't see, the craftsmen also smeared a few very special things on the cowhide, and the cowhide made out looked black and shiny, and it felt quite strong at a glance.

Dozens of craftsmen acted together, busy until dark, a piece of finished cowhide was finally ready, Feng Niangzi took out a needle, stabbed down on the bison hide, the cowhide was slightly dented but the needle was bounced open, and even the needle could not be pierced.

Lin Beixin said Niu Fork, Feng Niangzi nodded and smiled: "It's done." ”

After eating, the craftsmen continued, Lin Bei went back to Longtan first, and on the second day, Lin Bei rushed to the school, and the temporary new kraft bag was sewn again.

The blowing test is still the same, and after putting it into the water this time, the effect is much different from the previous one, there is only one air leakage, that is, the interface between the iron pipe and the cowhide.

This time, the remedy is to wrap a piece of cowhide around the iron pipe to make it close to the iron pipe, and after finishing it, finally all the places are not leaking.

"Double insurance is still very useful." Lin Beixin said.

After the kraft bag is opened, several craftsmen go down to the biogas tank, paste the cowhide around the biogas tank, and leave two openings, and then will use two or three layers of cowhide to sew all these openings, if this is not safe, then a layer of clay will be added on it, so that even if it will eventually leak air, but it will not leak too much, the leakage of air is either blocked by the clay, or it will be immersed in the clay, the probability of danger is not large.

Someone had already transported several large buckets of elephant manure from Xishan Township, spoonful by spoon into the biogas digester, Lin Bei watched from the side, and waited until the biogas digester was filled with almost two-thirds more than two-thirds of the manure, Lin Bei signaled that it was okay, and then sewed the cowhide and covered it with clay.

"My lord? And so it is? Cui Lan asked.

Lin Bei nodded, took a look at the weather, the weather is very hot, the fermentation of manure will be quite fast, generally speaking, the time for modern biogas digesters to produce biogas is about one week to ten days, the higher the temperature, the faster the biogas is produced, sometimes two to three days can be formed, Lin Bei hopes to succeed at one time.

PS: In fact, this method of concoction can take a long time, some years, but here it is shortened.