When Wang Tian was doing all this, Heizi was by his side the whole time, and in his focused gaze, there were doubts and puzzles, but from the occasional flash of light in his eyes, it could be seen that he still learned something or was inspired by something.

After Wang Tian did all this, he came to the kiln to check it, the flame under the kiln burned very strongly, and the tiles covered on the top of the kiln to raise the temperature in the kiln have also shown translucent red, which also shows that the temperature is enough.

Wang Tian took out the raw materials for smelting the axe and carefully put them one by one on the tiles on the roof of the kiln to preheat. Next, he had to burn the charcoal needed to smelt the molten iron.

One person was left to look after the fire, and the others either went to mud or to find large pieces of wood from tree trunks, as well as deciduous thatch, twigs and rotting wood that were easy to ignite.

He had dug a pit from the ground and made a circular pit about one meter in diameter. The trunks of the picked up trees are intertwined and erected in the center of the round pit, and then the wood is carefully placed one by one against the trunk in the center around the tree. It was not until it was about 30 centimeters away from the pit wall that the stacking was stopped.

Next, fill the gap between the pit wall and the wood, cover and wrap the erected wood, compact it with your hands, pick up the mud and apply it to the thatch, and use your hands to wipe the thatch that is close to it.

"Son of Heaven, are you going to burn a fire?" Kuroko on the side asked puzzled.

Although he did not know the principle that oxygen was needed for flame burning, he also understood that it was impossible to light a fire in an enclosed space.

He found that there was nothing in this kiln made by the Son of Heaven, and he didn't understand the point of burning it like this.

"Yes, I'm going to burn charcoal," Wang Tian replied.

Kuroko: "If it doesn't burn like this, it will be extinguished." What to do with charcoal? ”

Wang Tian: "Well, I have a way." The temperature of charcoal is high, the firepower is high, and if you want to make an axe, you must have it."

Kuroko: "I want charcoal and take it directly." As he spoke, he pointed to the fire that had been extinguished earlier.

Wang Tian: "It's different, this method is better to burn, and the higher the temperature will be when used to burn the fire."

Wang Tian couldn't explain to him the carbonization reaction that occurs when the charcoal is not completely oxidized. This charcoal does not have the same "flint" thermal effect as wood burned completely in the air.

Although Heizi was full of doubts, he did not stop in his hands, and helped Wang Tian to cover the entire pile of wood with mud, leaving only a doorway and stove.

Wang Tian picked up a wooden stick, stabbed the mud layer on the charcoal kiln flat on the ground, inserted the wooden stick into the kiln, made a ventilation hole, and then made six ventilation openings in a circle with a diameter of one meter at intervals.

The flame ignited the flammable thatch at the entrance of the door, and because of the existence of six ventilation holes, it quickly ignited the outermost circle of thatch in the kiln, and then gradually ignited the thatch wrapped in the mud.

After a minute or two, a layer of water vapor rises on the surface of the charcoal kiln wrapped in earth, and when the water vapor gradually disappears, the shell of the charcoal kiln begins to harden, and the flame in the kiln begins to burn from the bottom to the top, from the outside to the inside.

Wang Tian re-plugged three of the six ventilation holes, and half-blocked the door opening, and after observing for half an hour, he picked up the mud and re-painted it when he found that there were cracks and smoke in the kiln body.

As the number of cracked and smoking places gradually increased, Wang Tian called for sunspots and simply applied another layer of mud directly to the kiln shell. Wrap the whole kiln in full.

Leave the rest alone, just wait quietly for the combustion to finish.

There is a pot of tongs to smelt molten iron, a model for making axes, charcoal is almost there, and now there is still a blower that is not yet finished.

Wang Tian found two pieces of wet trees, cut them into suitable lengths and widths, and cut out a half-width notch in the middle of the two widths, and the two notches were buckled into a cross shape opposite each other, which was used as fan blades for the blower.

Then cut one end of a straight wooden stick the thickness of a thumb into a cross with a knife, insert the cross-shaped fan blade you just made into it like the tail of a dart, and tie the cross cut end of the stick tightly with a rope woven from soft teng bark. A cross fan rod with a rotating shaft is done.

Next, on a stone slab, a circular groove the size of a cross fan rod shaft is carved out with a knife, and the bottom end of the cross fan rod is stuck in the groove, and when the cross fan blade rotates, the bottom end is not easy to run around. This is equivalent to a flange.

Then find a thicker section of the tree pole and use a knife to drill out the bayonet groove at the top of the cross fan rod, which is equivalent to another flange.

Nail two thick wooden stakes into the ground with a stone hammer, and place the tree pole that has just drilled the round hole in the center of the two wooden stakes, and fix them at will.

Then the stone with grooves carved into the ground was placed, the two holes used as flanges were aligned, and the housing of the blower was placed over it.

Insert the bottom of the finished cross fan rod into the groove of the stone slab on the ground, and put the upper part of the cross fan rod into the hole of the tree pole.

Move the position of the blower housing slightly so that the cross fan rod can easily rotate in the blower housing, press the tree pole "flange" with your hand to determine the height position to be tied to the two wooden stakes, and then tie the two ends tightly.

In this way, the cross fan rod is tightly stuck between the stone slab "flange" placed on the ground and the tree pole "flange" tied to the two wooden stakes.

Wang Tian used the soft bark to pull out a twist rope to make a bow, and the twist rope was first wound around the cross fan rod and then tied. In this way, as long as the bow is pulled forward and backward, the rope on the bow will drive the cross fan rod to rotate quickly, which is much easier and less labor-saving than the rotation method of drilling wood directly for fire.

After the blower was done, Wang Tian began to use the clay stove, the caliber of this stove only needs to be slightly larger than the graphite tong pot, and the height can just put the graphite tong pot into the level.

After the stove was built according to the requirements, Wang Tian used a bamboo knife to divide the stove wall into three pieces from top to bottom, and then used mud to smear the internal and external gaps.

This is so that the furnace wall can be easily pushed down after the molten iron is melted, so that the graphite tong pot filled with molten iron is exposed, and then the graphite tong pot can be lifted with the finished tool, and the molten iron can be poured into the axe model to complete the casting of the axe.

As soon as the stove was built, Wang Tian took two bamboo poles the thickness of children's wrists to make the last tool needed for ironmaking: graphite tongs and pot clamps.

Put the middle of the two bamboo poles on the fire to heat, and then let the two adult primitives bend a Ω bend in the middle of the bamboo poles according to the arc of the graphite tong pot, tie one end of the two bamboo poles, and when pouring the molten iron, the other end is opened, and then the graphite tong pot is stuck, and the two quickly lift the molten iron and pour the molten iron into the axe model to complete the casting of the axe.