Having solved the problem of the intelligence organization and the cantonment corps, Ferdinand turned his attention to the second voyage.

The navigation conditions during the period of the Great Discoveries were very harsh, stranding was commonplace, and shipwrecks were purely normal, and even Dias was shipwrecked and died on the way back after Cabral discovered Brazil. Longitude cannot be determined.

Ferdinand couldn't change any of the above, of course, he was the first to use the Galen boat, at least a little more safe, but he had solutions to two other problems - freshwater preservation and scurvy. As long as lemons can solve everything, although rum can also be used, but at the moment he does not have time to grow sugar cane specifically for rum, and sugar cane is not adapted to the climate of Europe, and now the production is not high.

Whole lemons can be stored for about a month at room temperature. Adding a few drops of lime juice to fresh water can effectively preserve fresh water.

But a month, just enough time to get from Europe to the New World, and there was nothing to be done about the further voyage. In addition, Ferdinand has also read some online articles, it seems that lime juice is not a cure for all diseases, in fact, it is not that deep, and after staying in warm waters for a long time, fresh water will still spoil, and it has to rely on rum to solve it.

But Ferdinand didn't give up easily, and his countermeasure was to extract natural citric acid directly from lemons.

The extraction process of natural citric acid is mainly as follows:

1. Ingredients: Squeeze the lemon juice.

2. Neutralization: When the lemon juice is heated to 75 degrees Celsius, gradually add calcium carbonate milk slurry (preferably 15% concentration), continue to heat for 2 hours, the initial temperature is controlled at about 5 degrees Celsius, and finally it can be raised to 100 degrees Celsius, until the solution is blue-green, which means that the neutralization reaction has been completed. Then let it stand to precipitate, and this precipitate is calcium fruit acid (mainly calcium citrate).

3. Salt removal: The obtained calcium citrate contains salt, which can be washed with clean water, heated to 70-80 degrees Celsius, repeated many times until the salt is removed, and dried for later use.

4. Acidolysis: calcium citrate slurry is heated to 60-70 degrees Celsius, sulfuric acid with a concentration of 35% is added, boiled for about 3 hours, and the calcium citrate decomposition is completed, that is, the static precipitation, and the supernatant is a dark red citric acid solution.

5. Concentration and crystallization: Concentrate the dark red citric acid solution until the solid content is 75%, and then let it stand in the crystallization cylinder for crystallization. Crystallization can be completed in 4-5 days.

At this time, Ferdinand's previous scientific work was valuable, for example, he could now measure the temperature in the Celsius. As for the concentration of sulfuric acid? Concentrated or pure sulfuric acid is diluted to 2/5 and done.

For the time being, Ferdinand did not care about the large-scale industrial production of sulfuric acid, but instead used the early mass production method discovered in the 17th century - mixing sulfur with potassium nitrate and heating it to produce sulfuric acid, in which potassium nitrate decomposes and oxidizes sulfur to make it sulfur trioxide, which can be mixed with water and turned into sulfuric acid.

It seems that technology is really a ring after a ring, and the technology tree is not where you want to click.

Under the conditions of this era, Ferdinand did not use activated carbon for any decolorization, and the dark red crystalline hydrate looked just as beautiful.

Citric acid is a food preservative and an ingredient in products such as cosmetics, pharmaceuticals, and beverages. The shelf life of citric acid is three years from the date of manufacture. When stored in its original sealed container, the chemical composition and potency of this acid remain stable for at least 5 years. It is completely enough for navigation.

However, this does not mean that lemons are not needed, lemons are rich in vitamin C, which is a powerful weapon against diseases and symptoms such as scurvy, heat stroke, polydipsia, and bronchitis.

Lemon in Europe from the mid-15th century in the Italian city of Genoa began to be planted, Villafaranca lemon produced in Sicily, Italy, the fruit is oval, a single fruit weighs about 140g, less seeds, the top of the fruit papillae is obvious, the peel is light yellow, smooth, the flesh is soft and juicy, the taste is sour, the aroma is strong, and the quality is good.

Ferdinand therefore ordered hundreds of lemon trees from Sicily for citric acid production, as well as some for Sardinia. At this time, the Spanish mainland also began to produce lemons, so he didn't bother.

The fleets of this era were on large voyages, and countless people died of scurvy because of the deterioration of fresh water, and the cost of using alcohol as a substitute was very high. Now with the citric acid production process, Ferdinand's fleet was able to achieve significant cost savings and reduced personnel losses.

Naturally, this technique required strict secrecy, and citric acid extraction was only carried out in Sardinia, and since the Niedhogg group was based in Sardinia, their priority was naturally technical secrecy. If you can't keep your own skills, what are you talking about spying on your opponent? When it came to secrecy, Ferdinand was very confident. At that time, Britain only banned textile workers from leaving the country by legislation, and kept the water-powered spinning machine for ten years, and it was well known that under the situation that countries were thirsty for "virtuous", there was no reason why he couldn't do it.

Well, the application of citric acid should also be limited, for example, this time Ferdinand only added 34 ships to store citric acid and some lemons, and even Columbus did not know about such a thing. The original history of 17 ships loaded with dignitaries and noble sailors, there was no unity and reliability to speak of. Ferdinand couldn't trust them. For example, there were a small number of Aragonese on this voyage, but Ferdinand was almost ashamed to meet them, and later all of them contracted syphilis, not to mention, and ran back to Aragon to complain to Ferdinand, but the original owner was still interested in "administering justice" for them, according to Ferdinand's opinion, Columbus was in trouble, but before that, hang these guys.

Therefore, Ferdinand will only reserve lemons and citric acid on the expeditions and royal fleets under his direct control, and then expand them full, as for other countries, let them drink more first, otherwise his rum and sherry will not be able to spend money in the future.

In fact, in addition to artificial secrecy measures, Ferdinand also has a natural protective net, which is the technological gap.

First of all, the thermometer has to know how to do it, of course, it is not too difficult, but the workers and craftsmen are not told, so it takes a lot of work, and there are lemon trees, not every country has sufficient resources. To support the navigation industry of the whole country, it is obviously not enough to buy it alone. Another important point is the large-scale production of sulfuric acid! This is carried out separately from the production of citric acid, and Europe at this time, for more than 200 years, did not know how to carry out even the lowest large-scale production of sulfuric acid, so even if the rest of Europe knew the secret, there was nothing they could do about it, so they could only use lemon juice, which still cost a lot of wine, and the cost still could not be reduced.

Moreover, if the European countries, especially Portugal and England, did succeed in stealing, it would not necessarily be of much benefit, because Ferdinand would have liked them to take the initiative to make trouble and give themselves a reason to start a war. France also had to take it easy, and if they did something emotionally hurtful, it would not be strange for the Spanish volunteers to appear in the barracks of the Emperor of the Holy Arm.