Of course, the sea salt directly dried cannot be food grade, at most it can be regarded as an industrial raw material.

To put it simply, it's industrial salt.

In the future, tens of millions of tons of sea salt will be refined into edible salt every year, and most of the others will become industrial raw materials - just like Li Yuanjia now sees sea salt, although it is not particularly dirty, but Huang Bulaji is also black in some places, obviously mixed with a lot of impurities.

And these impurities, it's just what you can see.

Even after repeated filtration, after removing the insoluble impurities in these sea salts, there are actually impurities such as calcium chloride and magnesium chloride, which are mixed with a large amount of sodium chloride. For example, the reason why seawater makes people feel bitter in addition to being salty is actually due to magnesium chloride.

In fact, if it's just a little bitter, it's just that, the key is that in addition to the bad taste, these sea salts are also poisonous! You may be fine if you eat a little, but if you eat too much......

"So, it makes sense that the ancients didn't live long!"

After pondering for a long time, Li Yuanjia let out a low sigh, and couldn't help but think of a statement that used to be very nonsense, but now feels very reliable - the ancient regime implemented a salt monopoly, in addition to making money, it also has the role of protecting ordinary people.

Because whether it is sea salt or mineral salt, there are too many impurities.

Especially those toxic heavy metal impurities, before there is no good way to get rid of them, if ordinary people eat salt without moderation, I am afraid it is really better to eat less. All Li Yuanjia has seen a saying in his previous life, that is, although the salt monopoly system has pushed up the price of salt, it has also protected the health of the people......

Whether it is true or false will not be mentioned for the time being, but it is indeed a fact that these sea salts in front of him stumped Li Yuanjia.

Anyway, after going around the study a few times, Li Yuanjia couldn't remember it very well, and finally could only order Chunyan to close the door of the study from the outside, and after telling her that no one was allowed to enter, he came to the innermost row of bookshelves in the study.

Luckily, Li Yuanjia found what he was looking for a minute later.

A book he wrote many years ago...... When he saw the words in the book, Li Yuanjia was subconsciously stunned for a while, and couldn't help but recall that he had finally made a willow branch charcoal pen and hurriedly wrote these words on the same rough white paper with a crude charcoal pen.

At that time, many of his memories were still very clear.

For example, those medical knowledge, as well as the mathematics, physics and chemistry knowledge that he had studied, all the parts that could be remembered were recorded by Li Yuanjia with various symbols that the Tang people could not understand.

In fact, that year, Li Yuanjia also recorded four other books.

It's just that what is recorded in those books is not scientific knowledge, but the poems he has read and memorized, and if he takes them out, he can instantly become a poet emperor and poet. It's just that the poetry collection sprinkled with tens of thousands of words was burned by Li Yuanjia with gritted teeth on the day he wrote the last word.

Until now, he still feels distressed when he thinks about it......

Flipping through the high school chemistry book in his memory, Li Yuanjiazai carefully looked at it page by page, looking for what he wanted to recall desperately.

There are too many types of impurities in seawater.

But if it is summed up, there are nothing more than two kinds, one is soluble impurities and the other is insoluble impurities.

Those insoluble impurities are best done, dissolving these sea salts in water and then filtering them will solve the problem...... The coarse ones can be gauze, and the smaller ones can be made by Wang Pu with filter paper, and it can always be solved with a little more time and process.

But with soluble impurities, it's a bit of a problem.

Desperately recalling, all Li Yuanjia can think of are magnesium chloride and calcium chloride, as if there is any barium or something...... But unfortunately, I can't remember the specifics at all.

Fortunately, after looking at it for a while, Li Yuanjia finally found a way to remove magnesium chloride and calcium chloride - sodium hydroxide can dry out magnesium chloride, and sodium carbonate can dry out calcium chloride.

Sodium hydroxide, commonly known as caustic soda, is a highly corrosive alkali; And sodium carbonate, commonly known as soda ash, is actually a salt!

And then......

After studying this book for a long time, the expression on Li Yuanjia's face gradually became strange: "Hehe, is it really that easy?" Why does it feel unreal? ”

There is no shortage of trona minerals in China, for example, there are many in Henan, and the sodium carbonate content is quite high...... In the past, Li Yuanjia used the needs of making movable type alloys and papermaking, but he collected minerals from many places, so he knew this very well. After the sodium carbonate is dissolved and purified, clear lime water is added to filter out the precipitated calcium carbonate, and what remains is sodium hydroxide solution, that is, caustic soda......

It's not complicated, it's just that purity is not guaranteed.

So, can sea salt be purified?

So, can the chemical industry finally be opened in this era?

Blinking desperately, the corners of Li Yuanjia's mouth soon showed a strange smile: what I thought would be very difficult suddenly became so simple, this strong contrast is really too ...... It's so cool!

"Hahaha......"

So after closing the door for half an hour, the spring smoke outside the door was loyally guarding the study, and I heard a burst of comfortable laughter inside the door. It's just that the maid's face, who has long been accustomed to the laughter of her own king, has not changed at all, and she is still standing straight at the gate, quietly waiting for the person inside......

……

Just when Li Yuanjia was laughing because chemistry might set sail during the Zhenguan period of the Tang Dynasty, near Hanwang Farm outside the city, Chen Mu and Wang Pu were heartbroken because of the arrival of one person!

"Mr. Chen, this is absolutely impossible!"

After taking a deep breath, Wang Pu frowned and said: "Now that the output of the dumping workshop has reached its peak, it is very difficult to make even one more, let alone one hundred more units per month...... We can't do this at all! ”

Ignoring Wang Pu's words at all, the man who came waved his hand vigorously, and said loudly in an unquestionable tone: "I don't care what you mean by output and peak, but in any case, you must make an extra hundred overturns every month!" Hmph, there is a great drought in the world, and now even His Majesty is avoiding the main hall because of this, reducing various expenses, and letting you wait for an extra 100 overturned cars every month...... If you shirk it again, Hugh blames the official for being polite! ”

“……”

Hearing this man's unceremonious words, Wang Pu and Chen Mu's faces became extremely ugly at the same time.

You are welcome?

If someone else said this, Wang Pu would dare to let people beat him out! But the other party came from Jiucheng Palace, which made the two of them congenitally weaker in terms of momentum.

It's just an impossible task to make an extra 100 overturns every month!

Of course, they knew about the great drought in the world, so since February, the overturning workshop has begun to make overturned cars with all its might, and the craftsmen and handymen have been working early and late at night, and they are still in the workshop.

Make another 100 units a month, it's basically a dream!

So after a moment of silence, Wang Pu said dryly: "Mr. Chen, I really can't do this matter, so please allow me to send someone to Chang'an to ask the king......"

"King Han?"

After listening to Wang Pu's words, he seemed to think that he was pressing himself against King Han, and the man's face instantly became gloomy, and he said angrily: "Even if King Han comes, you must make it for me every month!" ”