After sending away the dehuan, Guo Kang took a group of elated priests and continued to the foot of the mountain.

"A lot of our equipment is made here." Guo Kang said: "Do you remember the mirror behind the giant of light before? ”

"Making a regular shape of a monolithic spherical mirror at a time is too demanding for craftsmanship. So, it's not a whole mirror, it's assembled with a lot of flat mirrors. He told the crowd, "Each mirror is about the size of two palms, so it's much easier." ”

"You said we made them ourselves?" Brother Dmitry asked in surprise.

"yes." Tuhuan nodded: "I think the paper has to be imported from the Ming Dynasty, which is too exaggerated." If you can't make glass, it will be miserable. ”

"Don't underestimate the paper." Guo Kang reminded: "The porcelain thing, the Europeans pondered for three or four hundred years, and they were hard fired with cross-era technology, and they were still fired. But that kind of translucent calligraphy and painting paper will be at least 500 years later. If so, the technical gap is bigger than that of porcelain. ”

"Now the sea route is not passable, and the land transportation is not convenient, and those papers are treasures treasured by my grandfather. It took me a lot of effort to get some from him and make a Brother Celestial animation. In the past, when we made samples, we could only learn from Europeans and test cow bladders. ”

"Glass is one of the few technologies that we are more skilled in than in the East." He pointed out: "If you can't do it well, you can't talk about it." ”

He introduced all the way and led everyone to the workshop.

"Mercury is often used here, and it's poisonous, so we can just look at it from afar." He pointed to a workshop, "Let's take a look here." This is where flat glass is made. ”

He led the people up the stairs outside the workshop to the second floor, and on the cloister, to see the scene inside.

The doors and windows on the first floor are open, and near the doorway there is a huge furnace where several glassmakers are heating the raw materials. Not far away, there was a row of pools filled with red-hot liquid, a huge wooden bellows beside them, and several men in black cloaks and strange beak masks.

"What is this doing?" Dmitry asked.

"In Roman times, flat glass was 'rolled out' on a workbench, crushed with an iron rod. Later, this technique was also lost, and today's flat glass is blown. I don't quite understand the specific process, but now the Venetian may understand this. Guo Kang said.

"This approach is too demanding on the process and is not easy to mass-produce, so we didn't try to imitate and surpass them, but used new ideas." He pointed to the pool: "Inside, it's melted tin." ”

"The burnt glass is lighter than the tin, and it floats on top of the liquid tin and spreads itself out so that it forms a flat surface. Then we cool the pool slowly to get the solidified glass. ”

"My Heavenly Father, how did you come up with that?" Dmitry was taken aback.

"This is the idea that the ancients understood, but their heating capacity was limited and they did not make a finished product." Guo Kang replied casually: "What we are studying here is the question of which liquid to choose—and it is not difficult. ”

"This liquid has to be heavier than liquid glass and at operating temperatures, it doesn't boil and it doesn't solidify. Like mercury, it boils too easily; And the temperature at which the copper liquefies is too high. ”

"That way, there are only a few metals to choose from. When I talk to other people, liquid lead is the first thing that comes to mind. ”

Dmitry nodded, not surprised. After all, the Romans were familiar with this thing, and it was normal to think of it......

"The problem with lead is that when heated, the smoke is very large and toxic. We thought about it again and switched to tin, which is less toxic. He pointed to the furnace, "That's the current situation. ”

"So how do you control this 'temperature', do you mean the degree of heat and cold?" Dmitry can only start with the technical term: "Can hot and cold also be quantitatively measured?" ”

"It may not be able to be quantified in detail, but it can be roughly estimated." Guo Kang said: "We put a long copper bar and a long iron bar of the same length in the tin pool. Both metals become longer when heated, but the elongation is different. We fasten the metal strips together so that one end extends out of the pool, and then compare the difference in length. ”

"There's a board on the edge of the pool, and it's for comparison." He pointed to the edge of the pool, "They've added a pointer now, which makes it more convenient." It may not be accurate, but at least you can record the appropriate empirical temperature and do so in the future. ”

"But it's a terrible environment over there. Staring at the pool hurts your eyes, so everyone wears black glasses. In addition, our tin is not very pure, and there will be smoke as well, so I suggest that they use cotton as a filter to protect themselves. The robe was used to keep out the spilled tin. ”

"Indeed, it looks professional." Tuhuan agreed.

"I think these are all necessary protections." Guo Kang muttered: "Actually, I think the finished product should be factory style, who knew that they would make it like this......"

"That's what they did." He took down a hood from the wall with glass lenses and a metal beak sewn on: "This beak is a piece of cotton." They're obsessed with the shape. ”

"Why didn't those glassmakers bring it?" Dmitry asked.

"They get used to it, and they feel that it is troublesome to bring it and affect the physical work. Although it was right next to it, someone had to manually lift the liquid glass over, but they didn't think it mattered. Guo Kang shook his head and said.

"Our workshop management is very unregulated, but we can't do it now. Later, when I expanded production, I saw if I could build a partition wall, separate the two sides, and leave a special feeding port to pour glass. ”

"In addition, every time I make it, I have to blow it with special gas. After pouring, the whole tin pool has to be cooled, which is very wasteful and the effect is also very bad. A lot of the glass was either deformed or exploded. In short, there are a lot of things to improve here, and it is also very troublesome to produce, and it is still experimental in nature. ”

"Now the main product is over there." He pointed to the opposite side of the workshop: "To put it simply, blow a glass bottle, then cut it, burn it soft, spread it on the workbench, and then roll it flat. ”

"This is an improved version of the ancient Roman process, with the advantage that it is not difficult to make bottles, and it is easier to go from bottles to glass plates than to directly press a puddle of liquid glass."

"Due to the blowing technology and the size of the workbench, we still can't make very large glass, but it is possible to make something half a person high. That's enough for now. ”

(End of chapter)