Aqua regia is so dangerous that it can cause great damage when it touches people. In desperation, Marin had to temporarily abandon the experiment of corrosive iron doors of aqua regia and develop gas masks first.

Gas mask Marin is no stranger, when the family raised silkworms in the previous life, because they had to be disinfected with quicklime frequently, Marin's mother wore a farmer's version of the gas mask. The so-called farmer's version of the gas mask is actually the original gas mask, with the core activated carbon part removed. Because, the farmer's version of the gas mask, its function is mainly to prevent the eyes and respiratory tract of silkworm farmers from being burned by quicklime. Just add a simple filter sieve, even without activated carbon. After all, quicklime is solid, not poisonous.

And if Marlin wants to make a real gas mask, in fact, he only needs to fill the filter screen in front of the mouth and nose of the farmer's version of the gas mask with activated carbon.

But first...... Marlin wants to engage in activated carbon first......

So, Marin hired craftsmen to make a simple farmer's version of a gas mask. It's easy, but it's all leather sewn around the edges of the eyes and wrapped in a hood-like space. Because there was no plastic, Marin went straight to the wooden shelves. Marin's craftsmen were able to even make pocket watches, simple gadgets that could be made effortlessly.

Then, it's time to get activated carbon. This is a more troublesome point, Ma Lin remembers that activated carbon mainly has chemical activation method and water vapor activation method.

However, Marin remembers that activated carbon produced by chemical activation is often toxic and can only be used for industrial impurities removal and filtration. Activated carbon used in food production is often produced by impacting charcoal with high-temperature water vapor. Chemically activated carbon is often produced directly from coal.

The chemical Famarin is not very clear about the technical content, but the physical Famarin still remembers. The specific process is to first put coconut shells and other wood materials in a furnace at high temperature to isolate air and heat them, so that they can be carbonized into charcoal. During the carbonization process, substances such as methanol inside the wood or coconut shell volatilize at high temperatures, leaving some pores inside the charcoal in the first place. But that's not enough......

After that, the charcoal with smaller particles is placed on a metal strainer and placed in the furnace. The water vapor that is introduced at high temperature and high pressure is vigorously washed from the bottom to the top of the metal mesh to create more voids and facilitate adsorption. And this water vapor often has a temperature of more than 500 degrees. Even, it can reach 800 degrees......

……

Well, high-temperature and high-pressure water vapor...... This is to force Marlin to do a pressure cooker......

Didn't say it - get on the pressure cooker first......

Then, a pressure cooker made of soft and thick elephant skin as a leather gasket was born......

In fact, when Marin was making paper, he made large sealed metal containers, and also added cowhide gaskets to seal the air. However, the cowhide is a bit thin, and the effect of breath-holding is not very good. But in any case, it is enough.

And this time, because when Marin sent people to Senegal to hunt rhino skins before, he hunted a lot of elephants by the way. As a result, thick, soft elephant skins were sent to the mainland.

Although elephant skin is thick, it is too soft to make armor. However, it is very suitable for making a leather sofa, which is much more comfortable than cowhide.

And now, Marlin suddenly discovered that elephant skin, a thick and soft leather, seems to be very suitable for making a leather gasket for pressure cookers......

Even, in order to make there be no gaps between the face and the gas mask, Marin also used soft and thick elephant skin to replace the rubber edge of the gas mask of later generations, so as to achieve the effect of full breath holding.

After the pressure cooker was ready, Marin had a metal mesh made of copper wire, but copper is also easy to oxidize under high temperature water vapor. So Marlin threw the copper wire mesh into the molten zinc and soaked it to get a galvanized layer. Molten zinc is easy to oxidize, but after oxidation, the oxide layer formed is very resistant to corrosion and oxidation.

Marin then had copper tubes and boilers built to create a system for producing activated carbon. Marin then ordered the pressure cooker to boil the water......

The pressure cooker made by Marin was different from the small pressure cookers used in later kitchens, which were used in industrial production with very thick walls and heavy locking mechanisms on the lid. In this way, it is not as easy to fry as the kitchen pressure cooker of later generations.

After boiling for a while, it felt almost over, and the worker, who wore armor to prevent explosions, pulled down the valve......

Suddenly, a stream of high-temperature and high-pressure hot water vapor rushed violently towards the copper furnace along the copper pipe, swept over the metal mesh at a rapid speed, and washed the charcoal particles on the net into a flying air. When the vapor passed, the charcoal particles fell back to the metal mesh......

After that, Marlin had this done it many times before he took out the net of activated carbon......

……

After getting the activated carbon, it is natural to test the effect. Marlin packs activated charcoal into a farmer's version of his gas mask. Then, find someone to test the effect......

This time it was a poison gas test, so naturally he would not look for his soldiers. Then, one of the death row inmates in the big guy was brought out......

Marin had the death row prisoners tied up, and then, in front of him, put a bottle of aqua regia in front of him, and threw another piece of iron into it......

The piece of iron entered the aqua regia and churned violently, reacting quickly. Then, a large amount of nitric oxide gas floated up and rushed to the door of the death row inmate......

But until the iron was dissolved, the death row prisoner did not pass out......

"Good, a success!" Marin happily clenched his fists.

It's no wonder, after all, Marin had come into contact with a farmer's version of a gas mask in his previous life. When I was a child, I often took my mother's farmer's gas mask out to play war games with my friends. Therefore, gas masks are still well understood. Otherwise, it wouldn't be so easy to imitate. If it was something he hadn't seen before, even if he knew the principle, it wouldn't be so easy to make.

In addition, elephant skin is a really good thing, thick and soft. In many cases, it can completely replace the role of rubber. The rubber trees that Marin has planted have not yet grown for 6 years, and they can't tap rubber. So, I had to use elephant skin to deal with it first.

As for protecting elephants? No kidding! The protection of elephants in later generations is due to the fact that humans have hunted too many elephants with advanced hunting rifles, resulting in the endangerment of elephants, so it is necessary to protect elephants.

In this era, elephants have few natural predators. Because, even if the elephant herd is a lion, it does not dare to provoke. Even the powerful tribes in Africa have to mobilize their tribes to dare to provoke elephants.

Marin later generations saw a video of Lao Hei hunting elephants with a javelin, and in that video, Lao Hei was all over the mountains, at least thousands of people. In order to prevent the elephants from fighting back, they dressed themselves up in fancy clothes (in fact, to scare the beasts) and then kept letting out ghost howls to scare the elephants. The elephants were frightened and began to flee. That's when these old blacks really began to hunt the stragglers with javelins. If the elephants had not been frightened, but provoked, Nimana would have been trampled to death......

Moreover, it is difficult for stone javelins to pierce thick elephant skins, unless they are metal spearheads. Therefore, in this era, there are very few old blacks who dare to provoke elephant herds. Because of the old black at this time, most of them are in the Stone Age.

In front of the powerful "elephant master", the old black of the Stone Age was scared and trembled, and he was afraid of being spoiled by the elephant herd when he farmed, how dare he harm the elephants?

Therefore, the Marin faction killed elephants in Senegal, and even won the gratitude of the local black......

……

After confirming that the gas mask was indeed effective, Marin began to experiment with aqua regia to corrode the iron door......