A question is, what is the saturated solubility of potassium hydroxide solution at room temperature, what is the solubility in the boiling state, and what is the saturated solubility in a pressure cooker at a temperature exceeding 100 degrees. Also, the potassium hydroxide solution in the saturated state is alkaline.

How much it is, these Li Mengxi have no idea.

He only knows that the temperature is related to the solubility, the solubility is related to the strength of the alkaline, and the strength of the alkaline is closely related to the effect of pulping for papermaking.

Therefore, the strength of alkalinity is directly related to the quality of papermaking.

After successful evaporation and crystallization, extremely pure potassium hydroxide solid is obtained. There is no need to use plant ash, and the color of the paper will not be darkened due to plant ash.

Li Mengxi felt that two spoonfuls of solid potassium hydroxide was too little. Although there was only one pressure cooker, there were too many ordinary pottery jars. There was no need for a pressure cooker to cook potassium hydroxide. Li Mengxi simply found fifty jars, and then another

Many people are available, so a large group of people come over to help cook together.

The same process, first fill the urn with clean water, then add plant ash as much as possible, then boil until it boils. After boiling, wait for a while, stop the fire, then wait for the plant ash solution to cool down, and then filter it with a silk filter.

.

This is the first step.

Next, in the second step, heat the filtered solution and keep boiling until the water is dry.

Fifty urns were started at the same time, and in the evening, not long after nightfall, each urn was completed one after another.

Li Mengxi was very busy. He was holding a small bowl. If the urn burned dry, he would take a small spoon and scrape out the white potassium hydroxide solid at the bottom of the urn, and then put it in the bowl.

When Li Mengxi collected the fourth jar, there was already a bowl of potassium hydroxide at the bottom of the bowl. By the eighth jar, there was more potassium hydroxide in the bowl.

The tenth urn, the twentieth urn, the fiftieth urn.

After collecting fifty jars of potassium hydroxide, Li Mengxi got almost half a bowl of potassium hydroxide and half a bowl of crystallized potassium hydroxide.

When cooking, add half a bowl of salt, it will be very salty.

In the same way, if you put half a bowl of potassium hydroxide into the pot, it will become alkaline.

The only drawback is that the filtration is not good enough and the water is not pure water. In addition to a small amount of plant ash, the potassium hydroxide finally evaporated also contains a small amount of gravel and other impurities.

Under the oil lamp, Li Mengxi twirled a needle. He used the needle to check the potassium hydroxide in the bowl. Li Mengxi felt that in terms of purity in chemistry, the purity of this half bowl of potassium hydroxide must be 100%.

Probably over ninety.

The pressure cooker is just that big. If you pour half a bowl of potassium hydroxide with a purity of 90%, it will definitely be far oversaturated.

More important than saturation, potassium hydroxide has absolutely no color pollution.

Li Mengxi told Guan Yu that he could try cooking another pot of paper pulp. The paper would definitely be much whiter when cooked in this pot.

In Guan Yu's eyes, Li Mengxi was simply an expert in papermaking. Li Mengxi said that the paper would definitely turn white, so it would definitely turn white. Guan Yu had no doubt about this.

Guan Yu, who was already very proficient in the papermaking process, poured the chopped hemp and clean water that he had prepared long ago into the pressure cooker. After pouring, when it was time to add the plant ash, Li Mengxi came over and took half a bowl of solid potassium hydroxide.

To Guan Yu.

Guan Yu took the bowl and glanced at the white flaky things in the bowl that were similar to salt. He asked, "Pour them all?"

Li Mengxi thought for a moment and said, "Fall them all!"

He wanted to see what would happen if he added potassium hydroxide to death.

Guan Yu followed his instructions and poured half a bowl of potassium hydroxide from fifty jars into the pressure cooker.

Then, following the same process as before, the blacksmiths clamped the molten iron and sealed the pressure cooker.

Then, there is a long sealing and heating process.

In the middle of the night, the paper pulp had been boiled for more than three hours. It was estimated that it was almost done. Stop the fire and let it sit. After the pot cooled down, a blacksmith wearing armor and a helmet came over and carefully looked at the iron seal.

It started to chisel with a clanging sound.

With a hiss, the iron seal broke, and high-pressure steam immediately shot out.

The blacksmith, who was already familiar with his work, ran away the moment the steam burst out.

The steam in the pressure cooker kept coming out. After a long time, when the steam was exhausted, the craftsman came back and smashed all the iron seals.

After the pot was boiled, Li Mengxi and Guan Yu went up to take a look. No matter whether the pulp was cooked through or not, there was not much difference in appearance.

But this time, the pulp cooked after adding a sufficient amount of solid potassium hydroxide was obviously different from the one cooked before. The pulp in the pot was cooked with a white layer on top, just like porridge that had been cooked for a long time.

It's like the layer of white foam on top.

No matter what, if things change, it means that adding solid potassium hydroxide has an obvious effect.

The pulp cooked in this pot only added potassium hydroxide and no plant ash. It must have been much whiter when it was made into paper. Li Mengxi couldn't wait to make paper with Guan Yu.

Guan Yu took the gauze net, lifted it up, and the paper pulp covered the net. With just one look at the color of the paper pulp, Guan Yu could tell that this time the paper pulp was not so black, but much whiter.

After that, he dried the paper on the fire. After the paper was dry, he lifted it up and looked at it again. Guan Yu's eyes lit up.

The paper made this time is no longer gray and black, and is several times whiter.

If the paper he made before was considered "what kind of paper" by Li Mengxi, then now, the dull paper has faded away, and Li Mengxi can barely feel that this paper is okay.

Just okay.

Because Li Mengxi discovered that there were still variegated colors on the paper. Although the plant ash was not added, the raw hemp itself also had color. The color in the raw hemp was not removed, so the paper produced still had color, with the semi-yellow color that belongs to the raw hemp.

Gray mottled color.

Guan Yu was extremely satisfied with the newly made paper. He handed the paper to Li Mengxi and said excitedly, "Xi'er, is this paper finally ready?"

"Yeah." Li Mengxi nodded calmly, "It's okay. It can be better, but it's still not white enough."

Guan Yu immediately looked sideways at Li Mengxi. The paper was white enough, but it was not white yet. How good must the paper be to be considered good?

At this point, Li Mengxi is still dissatisfied with paper.

As mentioned during the day, decolorization can also remove the variegated colors in the hemp. My brother said that you can wash it with water and wash the pulp several times with starch washing method to remove some impurities.

In addition, it can also be dyed directly to cover up the mottled colors of the original pulp paper with other colors.

The first method is the pulping method. This method is simple. It just adds water and stirs several times, and the impurities are settled through stirring and centrifugation.

Dyeing, dyeing, requires dyes.

Li Mengxi didn't know where dyes came from in the late Han Dynasty. He asked Guan Yu if he knew how to dye cloth, but Guan Yu didn't understand.

Dyeing cloth is a relatively high-end technology. If Guan Yu could dye cloth, and if he had this rare cooking skill, he would be selling mung beans in a shabby cart.
Chapter completed!