Taoists divide alchemy into inner and outer dan.

Neidan is to practice qi through breathing, meditating and cultivating penance, and seeking the path of cultivating immortals. However, not everyone yearns for the deep mountains and old forests, and can endure daily meditation and penance, and endure the loneliness of day after day to pursue the ethereal way of heaven.

Especially the biggest source of customers for cultivating immortals - princes and emperors. One by one, they are addicted to the worldly wine and wealth, and they are not satisfied with enjoying a lifetime, but they still want to occupy the world for the rest of their lives.

So there are some people who like it and offer to use external objects. For example, some natural treasures! Later, there was the theory of elixir.

Wai Dan is derived from the pre-Qin formula, in which minerals are smelted in a Dan furnace to make a "fairy pill"!

Taoists use various secret methods to smelt elixirs, which are used to eat, or directly consume certain sesame herbs, in order to ignite their own yin and turn them into yang energy, in order to achieve immortality.

If you take herbs and trees pills, it's fine, but if you take the Jinshi pills, then the old birthday star hanged himself for a long time, according to later research, the Jinshi pill contains more than 60 kinds of metals, and many people will be poisoned by heavy metals.

It's ridiculous to say that the people who want to live forever the most are the first to die, for example, Qin Shi Huang, who wants to live forever the most, is the best example.

However, it is not that the Wai Dan technique is useless, and it directly gave birth to the ancient chemical industry, and even the contribution of the gunpowder alchemists who invented the four major inventions.

The topic of pills was too heavy, especially when it involved Taoism and the powerful, the water was too deep, and the four of them wisely avoided this topic and concentrated on finding their purpose.

"That's it?" Qin Huaiyu touched the frost-white crystal, and said with a puzzled expression.

In a corner shop, the four finally found their target.

"A few young masters, this is the best wall frost." The owner of the shop was a gray-haired old man, and when he heard Qin Huaiyu's suspicions, he seemed to be insulted.

Wall frost is another name for saltpeter, because saltpeter often appears under the corners of the wall, and the color is as white as frost, it is called wall frost.

Merton looked at these white powders, and couldn't help but nod and said, "How much is this wall frost, I want them all"

"Seriously!" The store said with surprise on his face, and his heart had met a big customer this time. At this time, gunpowder was not yet popular, and saltpeter was of little use and was not easy to sell in ordinary times.

"How could the Mo family, who is famous in Chang'an, deceive you, a small shopkeeper!" At this moment, a teasing voice sounded behind him.

"Mo Jiazi!" The shopkeeper was stunned for a moment, although he was taking it for Taoism, but in the past six months, the Mo family has risen strongly, and it has already aroused the interest of the whole city in the pre-Qin Dynasty.

Merton looked back and saw Pound, dressed in regular clothes, looking at Merton with a smile.

"Ahh The faces of the four of them suddenly changed greatly, and their minds changed sharply, since Pang De appeared here, then Li Shimin must be in the Xuandu Temple.

"Grandpa Pang, how could you ...... Find it here! Merton stammered.

"Father-in-law, I happened to serve the nobles, and I happened to hear the report from the guards, there are people in strange clothes and sneaky deeds in the back streets, and it is really you." Pound looked at the strange dress of the four people, and couldn't help twitching the corners of his mouth, saying that with their dress, it was impossible to be low-key wherever they went.

Qin Huaiyu and the others immediately glared at Merton, if it weren't for his bad idea, how could they be so unlucky.

"Since my father-in-law has nobles to serve, then we won't bother." Qin Huaiyu said flatteringly, the soles of his feet slipped, as if he had slipped away.

Merton and the others nodded in unison, now they don't want to meet Li Shimin at all, they just want to leave Li Shimin to escape the summer after Li Shimin leaves Chang'an City, leave them in Chang'an City to have a good time, and after making ice in the future, they will dedicate the ice-making method to Jiucheng Palace.

"There's no hurry! It just so happens that the nobles want to see you! Pound said with a grin.

The heads of the four of them suddenly drooped, and the last bit of luck in their hearts was ruthlessly punctured.

"Young Master Mo, this wall frost ......" The shopkeeper hurriedly asked when he saw that the four of Mo Dun were leaving.

"Yes! Absolutely! Why not? Wrap it all up. Pound said with a smile, in addition to bringing back the four Merton, he was also interested in what Merton did, he was ordered by Li Shimin to keep an eye on Merton, but he knew how good Merton could toss, and once he made a move, it was definitely not a small matter.

"Yes! Be! The shopkeeper's face was suddenly full of excitement, and Merton's face turned black in an instant.

Gendo Temple.

Under the shade of a dense tree, Li Shimin and Yuan Shoucheng were sitting at the stone table drinking tea, and the two talked happily and burst into hearty laughter from time to time.

And under the tree next to it, Li Chengqian, Li Tai and Li Zhi also occupied another stone table.

While eating snacks and drinking tea, the three of them looked at the four people standing in the corner, and couldn't help but snicker.

The four of Merton stood in a row honestly, with an extremely upright attitude, like students who have made mistakes, waiting to be taught a lesson.

"You're wearing a nice outfit!" Li Chengqian looked at the clothes on the four of them with a look of great interest.

"Go."

The four of Merton suddenly glared angrily, this guy who fell into the well.

What's even more odious is that Li Zhi looked at the clothes of the four of Merton who were very different from ordinary people, snickered, and began to hold his stomach, if he wasn't afraid of attracting Li Shimin, he would have been lying on the ground and rolling.

And Li Tai looked at the four of Merton with interest, he was more interested in Merton himself than Merton's fancy clothes.

Among the many princes, Li Tai's knowledge can be said to be the best, even if you look at the entire Tang Dynasty, it is also first-class, but he has no confidence in Merton.

The unfathomable arithmetic and the poems that are famous in Chang'an City, coupled with the wisps of miracle-creating practical methods, convinced him.

"Why are you here?" Merton glanced at the opportunity and asked in a low voice like Li Chengqian.

Li Chengqian replied in a low voice: "My father is about to come to the Jiucheng Palace, and I came here today to repay my mother's wishes." ”

Merton suddenly realized, no wonder among the many princes, only the three princes born to the eldest grandson empress are here. ”

Since Sun Simiao stayed in Chang'an City, he often went to the palace to help Empress Changsun adjust her body, and after a few months of recuperation, it was very effective and her figure improved. I deliberately picked a good day and came to repay my vows.

The four of Morton looked at each other, and couldn't help but feel bitter in their hearts, why was he so unlucky, and he happened to touch the muzzle of the gun.

"What about you? What is this dress for? Li Chengqian asked.

"Cool!" The four of them spoke in unison