In the Ming Dynasty, there was still a glass process, but the road was a little off!

Yanshenzhen in the Ming Dynasty is the largest producer of medicinal jade, and what is produced is glass, and it is colored glass, just the kind of glass that is completely opaque and the color of jade!

In terms of technology, the production of medicinal jade is the same as that of glass, and the raw materials are also the same, with only slight differences.

If the colorless and transparent crystal that the ancients have been pursuing instead of jade, then it is very likely that the Ming Dynasty would have mastered the process of making colorless transparent glass.

That's why demand determines the market, and demand determines the direction of a technology.

Yan Zheng's needs are colorless and transparent, colored and transparent, and completely smooth.

In addition, there is a huge demand for the chemical industry. This is the only material he has the conditions to manufacture that can withstand acid and alkali corrosion.

Chemistry needs to be taught and researched, and there is already a demand for glass, at least all kinds of reaction dishes, test tubes, and glass tubes are the basis of chemical experiments.

"Teacher, you're here!"

As soon as Yan Zheng walked to the shed, the students were busy greeting each other.

He nodded and walked slowly to the sintering furnace.

The raw material is being sintered in order to sinter the raw material into a glass frit, a step that reduces the melting time of the subsequent steps.

Raw materials include quartz sand, fluorite, dolomite, these three minerals are available on Dongqin Island, and if you want to import a large number of them, Zhejiang, Fujian, and Japan have them.

Yan Zheng sat for a while, and several students got out the sintered iron trough, and the raw materials in it had been cemented into glass frit.

After the water has cooled, it is smashed into suitable pieces with a hammer and thrown into a closed crucible.

While the glass melts are put in, there are also students who throw saltpeter and seaweed ash on the side.

Now there is no ability to make soda ash, so it can only be replaced by seagrass ash, and it is okay to use grass ash, but it is not as good as seagrass ash.

Saltpeter is added for decolorization, and most decolorizers are actually oxidants, and saltpeter is the cheapest oxidant that Yan Zheng can find.

At present, the output of nitrate in Mocheng has reached more than 20 tons per month, and in addition to its own use, it is also exported to Fujian and Japan in large quantities.

Soon, the two students cooperated to clamp the closed crucible into the circular glass furnace next to it.

This glass furnace is divided into three chambers: upper, middle and lower. The basement is used for heating, using coal.

The middle chamber has four arched openings, from which the closed crucible is placed, and after being inserted, the mouth is blocked with earth, leaving only a small hole.

The upper chamber is connected to the middle chamber by a small square opening in the center, which allows the tongue of fire to overflow throughout the middle chamber.

The heat can also flow from this small opening into the upper chamber, behind which there is also a ceramic annealing tunnel, where the glass can be annealed.

Such an ingenious stove, of course, is from Yan Zheng's hand!

"Looks like you're pretty skilled!" Yan Zheng smiled with satisfaction.

Wang Erhu on the side wiped his sweat and said: "It's too cumbersome, I'd rather go to steelmaking than glass!" ”

The rest of the students nodded approvingly, it is really that glass is not as good as molten steel, and when it cools, it can't be let cold casually, and it has to be annealed.

Of course, if it is a small piece of glass, it is okay not to anneal, anyway, the stress is not released, and the small glass will not break.

However, annealing of glass products can minimize or weaken the residual stress and optical inhomogeneity in the product, as well as stabilize the internal structure of the glass.

If the internal structure of a glass product that has not been annealed is not yet in a stable state, the glass density may change and become more prone to breakage.

Yan Zheng smiled and watched them continue to operate, the size of this glass furnace is actually very small, if the test is successful, it will have to be expanded.

After the four arches are installed, the crucibles are installed.

All the students breathed a sigh of relief, sat down on the ground one by one, and began to wait quietly.

Yan Zheng also took the opportunity to take out the blackboard and continued to lecture them.

While lecturing, let people stare at the fire in the stove.

About five hours later, with the cooperation of Wang Erhu and Deng Yong, a crucible was clamped out.

The solid raw material has been turned into a paste-like glass liquid, and after removing the scum on the surface, some students immediately added some table salt to it.

This is for clarification!

Yan Zheng originally prepared to use arsenic, but after considering its toxicity, he chose to use table salt!

The specific principle is that the salt evaporates at high temperature to produce large bubbles, which absorb and take away the fine and small bubbles in the original molten glass.

However, if table salt is used, it is accompanied by a stirring process, and an appropriate amount of saltpeter is added to this process to ensure complete decolorization.

Stirring is not random stirring, but is accompanied by a stirrer, a hollow clay cylinder about two-thirds the diameter of a crucible.

I saw a student desperately dragging the ceramic cylinder with a steel drill, and as the stirring progressed, the molten glass seemed to become silky and uniform.

After the salt and saltpeter had stopped, the student stirred for a while before making the stirrer.

The students were already sweating profusely, and the bright light made their eyes bloodshot.

In another time and space, early optical glass was created in this way. When the rabbit was in northern Shaanxi, he also used this method.

Although the optical properties of the glass products produced are not as good as those of later optical glasses, they are sufficient to make sextants, Keplerian telescopes, microscopes, and glasses.

After the molten glass is poured onto the iron trough and shaped into various shapes by the stamping method, it is put into the annealing pit and let it slowly annealed and cooled.

This process takes a bit long, two to three days, and even more than ten days for the production of large flat glass.

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"Whew, that's grinding!"

When the last glass product was put into the annealing pit, Wang Erhu and Deng Yongqi sat on the ground.

One in the physics group and the other in the chemistry group, both of them realized how difficult it is to be on the road to science.

Yan Zheng sat aside and said with a smile: "There is still a long way to go, and a lot of research can only be done by exhaustive methods, and it will be even more grinding when the time comes!" ”

Wang Erhu raised his head and said, "Teacher, why do you have to make such a good glass?" At first, we experimented, didn't we already build it? ”

Yan Zheng looked at him, then at the students present, and said with a smile: "Do you all have this kind of thought?" ”

Quite a few students nodded.

"Good!" Yan Zheng got up and said, "I'll tell you why!" ”

"Because we're going to make the best! You have also seen those inferior glasses, which have weak light transmittance, and are densely packed with small bubbles. First, we can't make optical instruments, second, we can't make goggles, and third, we can't make qualified chemical instruments, which can't meet our needs at all? ”

"Those inferior glass can still be useful for civilian use, but we can't use civilian standards, we must use higher standards! In the future, it will even score military standards, civilian standards, and laboratory standards! ”

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Three days later, the annealing was officially completed, and the first batch of glass products were translucent and pure, although there were still a few small bubbles, but most of the areas were guaranteed uniform optical properties.

If it is used as glassware, as a glass bottle, this kind of glass can fully meet the demand.

Just to make optical glass, it also needs a grinding process.

Although more than a dozen concave and convex mirrors were produced through the stamping method, the unpolished surface of the painting could not be used to make optical instruments at all.

Yan Zheng knew that he could use fine sand to polish, but there was no talent who could polish at all.

As a last resort, he could only mobilize the students and call on them to come up with a solution.

As a result, one student said that his father could polish a bronze mirror, which may be similar to polishing glass.

Yan Zheng was ecstatic after hearing this, and hurriedly launched a call for all the Ming descendants who could polish the bronze mirror to gather in the red room.

Facts have proved that the wisdom of the people is unlimited, and there is no need for Yan Zheng to teach them a new way of polishing, these craftsmen who sharpen the copper mirror, using the materials and methods of grinding the copper mirror, in less than two hours, will perfectly polish out a convex lens!

When they polish copper mirrors, they use mercury doped with tin dust to grind, and they also use this when polishing glass.

After Yan Zheng took a closer look, he understood that this abrasive was much better than the so-called fine sand.

Several craftsmen said that Dongqin was too hot, and it was more difficult to polish, so Yan Zheng directly asked people to use saltpeter to make ice and make some abrasives with lower temperatures.

It was found that at low temperatures, the original white metallic form of tin has turned into a gray powder, and the grinding speed has become much faster.

Yan Zheng knew that mercury was poisonous, so it was normal that this more effective polishing method was not recorded in the brochures of later generations.

After thinking about it for a while, he still chose to focus on the national foundation and let the craftsmen continue to polish in this way.

All he can provide is a cooler room, and the goggles and masks that will come later.

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