Sodium nitrate and potassium nitrate are very similar in nature, potassium nitrate is the main formula saltpeter component in black powder, in principle, sodium nitrate oxidation is stronger, and the explosion power is greater after adding black powder.

It's just that sodium nitrate is more absorbent than potassium nitrate, and the black powder prepared with it is very easy to freeze and not easy to preserve. However, if it was temporarily deployed within a few days before the war, it would be equivalent to upgrading the black powder, which would be an improvement.

But the most useful thing about sodium nitrate is not to make gunpowder, which can easily decompose when heated into a substance called sodium nitrite. What is this substance? In later generations, it was often said that leftovers would produce carcinogens called nitrites when left for a long time.

Nitrite is a general term for inorganic compounds, mainly including sodium nitrite and potassium nitrite, commonly known as industrial salt. Not much is said about their carcinogenicity, but this thing is said to be medical, a drug that can treat heart disease and hemangiomas.

Hong Tao will definitely not use it as a medicine, and with the current technology, it cannot extract sodium nitrite of medical purity. This toxic industrial salt is precisely to be used in food processing, and is prepared to be used as a preservative.

When an army fights a war, especially when it enters the territory of an enemy country, in addition to the command of weapons and personnel, logistics is also a major issue that cannot be ignored.

The Northern Song Dynasty army and the Western Xia fought for decades, winning and losing, Hong Tao did not pay much attention to the number of victories, but almost all the recorded defeat materials have been read, eight times out of ten because the logistics were not available, and there was no need for the enemy to fight, and the front-line army itself starved and crippled.

Hong Tao is not yet completely deep into the enemy's territory, although Mawei City is in the territory of Western Xia, but its location is relatively unique, and it is difficult to be besieged by a large army by taking advantage of the terrain.

But sooner or later, he would have to lead his troops into the real Western Xia hinterland, and whether it was a field battle or a siege battle, he would face the same logistical problems.

Hong Tao really didn't dare to be sloppy in this matter, and he didn't dare to pin his hopes on the heads of those grain officials in the Northern Song Dynasty, even if the crown was not completely assured. If you want to have peace of mind, you have to rely on yourself.

Compressing biscuits and canned food, this is the logistical solution that Hong Tao found.

Compressed biscuits are easy to make, with a screw press, and with a drying box, staple foods such as fried rice and fried noodles can easily be dried and compressed to a very small volume. Even if it can't catch up with the quality of compressed biscuits in later generations, only the mountaineering bag carried by the soldier can hold a month's ration.

But you can't eat fried rice and fried noodles every day with cold water, that thing can't pull out if you eat too much, and it can't provide enough nutrients, so you have to be assisted by vegetables and meat.

Now the problem is that both vegetables and meat are prone to spoilage. The common method used by the ancients was to pickle pickles and salted meat, which can appropriately prolong the spoilage time. However, as the temperature and humidity rise, these two foods cannot be stored for a long time.

Constipation and malnutrition alone are not too bad results, hygiene is the ultimate killer. Once a soldier has a large area of diarrhea, the battle is indeed impossible to fight, and the spread of the disease may not be controlled without the enemy.

Hong Tao has already made the relatively primitive cans, relying on heating and sealing them in porcelain jars with paraffin. The effect is better than not sealing, but it can't be stored for a long time, which is a headache for Hong Tao.

With sodium nitrite, this problem is solved, this inorganic compound is indeed toxic, but as long as the intake is controlled, there is no real harm to the human body. In fact, nitrite was often used as a preservative in the food processing industry in later generations, but it has only been banned in recent years.

As for what content is appropriate, Hong Tao doesn't know this standard, so he can only use stupid methods and test little by little.

Get a few samples of different contents for those Western Xia captives to try, eat for ten days and half a month, there is no reaction, the content is not too high, and then choose the lowest one from these levels to test the antiseptic effect, in the room temperature environment can make canned food not rotten for two months, basically qualified.

It not only solves the problem of canned food, but also creates a fist product for Huangzhou. In the past, Huangzhou was a poor place, with little special produce other than timber, horses and yaks.

Now, canned food in Huangzhou is a specialty, and once the output is large, it can be sold back to the cities in the mainland, so that the Song people can also taste fresh. If Emperor Shenzong and the General Staff really had the foresight, they should build a few more canning factories in the border states to replace the original types of military rations.

The direct effect of this is that the combat radius and duration of the Song army are much longer, which correspondingly reduces the logistical pressure, and the cost of war is reduced as soon as the inside and outside are integrated.

In addition to the fist products, canned food has also brought a number of employment places to Huangzhou. Food processing is a labor-intensive industry, which allows more spare labor to earn income.

They have earned money, and the life of the family is better, who is the first to thank you? Naturally, Lord Shuaisi, who brought about these changes, went to the emperor's temple to offer incense and worship the golden body of Emperor Shenzong.

From now on, whoever says that Lord Shuai Si is not good and His Majesty the Emperor is not good, these workers and their families will be the first to be unhappy.

What nation, righteousness, and country are put aside first, just ask if you can make everyone fed, clothed, and earn money? Yes, then you are just the same as Lord Shuaiji; No, get out of the way, don't delay everyone from going to work.

Hong Tao invested in the construction of a canning factory, in addition to meeting the needs of his army, he could also sell it to make money, and at the same time gain the hearts of the people, solve the problem of employment, provide tax revenue, and enrich himself and everyone in the entire industrial chain, killing several birds with one stone.

That's the great thing about serious businessmen, they often don't do things too much to the overall interests of society, because that kind of business doesn't last long. What kind of businessman likes to harm others and benefit himself? Except for a small group of profiteers who are vicious and short-sighted by nature, most of them are officials and businessmen.

Their industry is easy to come by, not by management but by power, so they do not deliberately run the market at all, it is all predatory management. How to make money and how to play, there are other industries when an industry is broken, the right is in hand, I have it in the world, I can play whatever industry you want!

Coming to the small courtyard of the laboratory, the children of the children's group and the youth group gathered together in twos and threes to do their favorite experiments, only Gao Yu squatted in front of the glass kiln in the corner, holding a pipe and blowing.

The shelves around him are full of his works, large and small, all of them, basically experimental vessels, mixed with a small number of gas lampshades and glass discs with high transparency.

It was the lens of the telescope, it was very difficult to get it, and if there was any distortion and bubbles, it would be useless. Even if the material and shape are perfect, they still have to be polished out of the convex and concave surfaces before they can be used.

"Silly boy, take a break, you won't be tired of blowing your mouth all day." Gao Yu was not white in the first place, but after arriving in Mawei City, it was even darker, and now the little black face has become a little flower face again. No matter how big a villain he was in his previous life, his performance is already very good now, making Hong Tao more and more unable to deliberately rectify his mind.

“…… Woo woo woo ...... "Gao Yu is blowing a large glass jar, and I can't tell what it's used for.

The blowing is at a critical moment, this kid is very serious, even if he sees Hong Tao coming, he is reluctant to remove his mouth from the blowpipe, just humming.

"Leave me alone, keep blowing! You have to have such a spirit to do things, you will be rewarded if you blow well, and if you blow bad, I will take you to ski. Hong Tao simply found two refractory bricks and sat down, looking at the glassware on the blowpipe.

This is really a matter of talent, I tried to blow glass when I was in Jinhe Bay, and I never succeeded. But when the soft and collapsed glass arrived in Gao Yu's hands, it was like having life, and if he wanted to make it drum, he would drum there, and he would be thin at whatever end. He has only studied such a craft for more than a month, and it is really possible to become the first blowsmith in the Great Song Dynasty in the future, and this mouth is money!

But Gao Yu seems to have fallen into a little problem after experiencing life and death, that is, he is afraid of snow and ice, and he can't go up if he can. In view of the fact that his injury has not yet healed, the youth group is not forced to train. But Hong Tao is really not a thing, he likes to see Gao Yu standing on the skis and sweating.