"Hurry up!" Lin Yi shouted, and Peach Eleven held back his strength and shook it even harder.

"Faster!" Still not fast enough, so Lin Yi shouted again.

Peach Eleven's face was flushed, holding the handle with both hands, and using all his strength to shake the handle.

He shook faster and faster, and soon, they couldn't see the outline of the grinding wheel, leaving only a grayish-white afterimage.

"Take it!" Lin Yi said to Tao Twelve.

"Yes." Peach Twelve held the iron rod in his hand, close to the grinding wheel, only to hear the sound of "bang", Peach Twelve was bounced out by a huge force, if he hadn't practiced since he was a child, the next plate was very stable, this time, it would have been ejected a long time ago.

Li Yu heard that loud noise, and Tao Twelve leaned back violently, and he knew why the owner didn't let him do this just now.

Obviously, Peach Eleven and Peach Twelve are more stable than him.

Seeing that Peach Twelve's face was pale, he then increased his strength to hold the iron rod, and then approached the rapidly rotating grinding wheel again.

The edge of the grinding wheel rubs against the edge of the iron rod ...... a few clicks, and after a few clicks, a little spark emerges from the place where the grinding wheel is connected to the iron bar.

Lin Yi looked at the spark and said, "Carefully observe the brightness, distance and number of sparks. ”

Li Yu was stunned, and hurriedly looked at it, only to see that the sparks flew out little by little, and there were more and more of them at a time.

"That's it!" Lin Yi gave an order, and Peach Eleven and Peach Twelve hurriedly put down the handle and iron rod in their hands, gasping for breath.

Peach Eleven exhaled a few breaths and said, "This is really tiring, madam, does this iron have to be tested like this every time?" ”

Lin Yi nodded.

"Oops." Peach Twelve sighed and said, "This is more tiring than training in the barracks, madam, you won't let the two of us stay here in the future to test the smelted iron." ”

Lin Yi said with a smile: "Before I find someone more suitable than the two of you, this job belongs to the two of you." ”

“……”

Peach Eleven and Peach Twelve instantly drooped their heads and looked at the grinding wheel with a sad expression.

At this time, Li Yu walked over and said, "Boss, just now I saw that the spark was very long and almost sprayed us, what does this mean?" Does this iron rod contain charcoal? ”

"Naturally." Lin Yidao: "Now, there is no way to smelt iron ore into a piece of pure iron. ”

When Li Yu heard this, he was a little stunned, he bent down and picked up the iron rod, turned it over and looked at it several times, and said: "This is obviously a piece of iron, but I really can't see where the charcoal comes from in it." ”

Lin Yidao: "The carbon contained in this iron is not charcoal, but carbon, if the carbon content in the iron is too high, then it will affect the toughness and hardness of the iron, so we make iron, the main thing is to remove impurities including carbon in it." ”

Lin Yi's words contained too much new vocabulary, and for a while, the three of them were confused.

"Wait, owner, what is carbon? What does it look like? ”

"Ma'am, what is the impurity?"

"Madam, is there something else hidden in this iron that we don't know about besides carbon?"

The three of them took turns, and the questions were one after the other.

They are so studious, Lin Yi is very pleased, according to the questions they asked, from simple to difficult, one by one to answer them.