Tired and sweaty, I dug seven or eight arm-thick winter bamboo shoots, took them home and opened the bamboo shoot shells, revealing the snow-white bamboo shoot flesh inside, cut them into boiling water to remove oxalic acid, and cut the cleaned beef into small pieces, put them into a large clay pot together, add pepper, ginger, garlic, herb fruit and sauce and put them on the earthen stove to simmer.

Because of the iron pot and tea tree fruit oil, Chen Xu couldn't wait to go to the vegetable garden to pull a basket of tender and tender vegetables, and Xing'er and Shui gently sat on a small bench to pick them up and wash them with water for later use.

Soon an hour passed, and a strong smell of beef emanated from the kitchen, which could be smelled all over the yard, and almost everyone felt that saliva was about to overflow from their mouths.

"Brother, I want to eat braised beef noodles!" Xing'er couldn't hold it back for a long time, holding Yu Ji's hand, the two children circled around the stove, and kept sucking saliva in their mouths.

"Engong, are you almost ready to cook noodles?" Yu Wuya kept licking his mouth, and had been squatting behind the stove in the kitchen from beginning to end to add firewood to the fire, replacing the position of the apricots on weekdays, Niu Dashi stood next to Chen Xu, Wang Wuwang and seven or four people were also crowded at the door of the kitchen, staring at the clay pot that kept boiling beef, and the hala kept falling, and Chen Jiang, who cooked every day, was directly squeezed out of the door, so he had to stand outside with Shui Qingrou and talk, looking happy, and the relationship between mother-in-law and daughter-in-law was a mess.

Chen Xu lifted the lid of the clay pot, and suddenly a rich aroma of beef spread in the kitchen.

Chen Xu used chopsticks to scoop up a lump of beef from the jar and put it in his mouth, chewed it slowly and swallowed it a few times, and a smile bloomed on his face.

Braised beef noodles are just like this, and they are even more fragrant than those eaten in later noodle restaurants.

"Goo Dong~" The kitchen sounded seven or eight swallowing sounds almost at the same time.

"Brother, I want to eat~" Apricot shouted.

So Chen Xu took out a clay bowl, scooped out two large spoonfuls of beef and bamboo shoots with thick soup from the clay pot with a bamboo spoon and handed them to Xing'er: "Be careful of scalding, take Yu Ji to the living room first and eat slowly!" ”

"Engong, I want to eat it too!" Seeing Xing'er and Yu Ji, the two little girls, happily walking away with a pottery bowl, Yu Wuya couldn't help it even more.

"Hurry, add firewood and boil water, I'm going to cook noodles!"

"Eh, good!" Yu Wuya nodded again and again, and hurriedly added wheat grass and branches to the earthen stove.

"Delicious, so delicious! The braised beef noodles really live up to their reputation, and it's really worth waiting for so long! ”

More than ten minutes later, Niu Dashi, Yu Wuya, Wang Wuya, and a total of six men squatted on the steps at the door of the kitchen, all holding a large pottery bowl, chopsticks dancing like a windmill, eating one by one, Yu Wuya was still humming while eating, and the words of praise were overflowing.

A big pot of noodles, a crockpot of bamboo shoots stewed beef, I ate a seven, seven, eight or eight in less than half an hour, and even the beef soup had bottomed out, and almost everyone ate it, and they began to burp one by one by touching their bellies.

And Chen Xu, Shui Qingrou, Chen Jiangshi and Xing'er Yu Ji The two little girls sat on the kang in the living room, sitting cross-legged around the low table, eating slowly and methodically, not only eating beef noodles, but also a large plate of stir-fried cabbage, crisp and tender, plus the fragrance of tea tree oil, it can be called the most comfortable and satisfying time that Chen Xu has eaten since he crossed over.

"This tender Chinese cabbage is really delicious when stir-fried like this!" Shui Qingrou is particularly fond of stir-fried cabbage, and praises while eating.

"That's nature!" Chen Xu was very proud, and said while eating, "There are few vegetables in winter, so let's eat more." ”

Yu Wuya came in from the kitchen with a cup of tea, and said while picking his teeth: "The green vegetable leaves are very delicious, and the beef and beef soup are really delicious!" ”

"Go to the side!" Chen Xu couldn't help but roll his eyes and continued to eat the little cabbage.

After eating a meal for more than an hour, everyone was satisfied, and the two little girls also ate a big bowl of noodles by themselves, and after they were full, they went to play hand in hand.

Yu Wuya opened the chessboard on the kang and invited Chen Xu to kill a few games of chess, but was completely ignored by Chen Xu, and Shui Qingrou also helped Chen Jiang clean up the dishes and chopsticks, Wang Wu saw that Yu Wuya was bored alone, and wanted to play a few games with him, but the two walked for less than ten minutes, Yu Wuya drove Wang Wu away, and then began to play with himself, on the kang for a while left and a while on the right, with words in his mouth, it seems that Shinto has symptoms of schizophrenia.

Chen Xu felt that his food was almost exhausted after drinking tea, and he went to the laboratory to get something, but he pushed the door in, but found that Xing'er and Yu Ji, the two little girls, were sneaky and didn't know what to do inside.

"Stop!" Chen Xu hurriedly called out to the two little girls, "What are you two doing here secretly?" ”

"Uncle Xu, let's ...... What did we do? Yu Ji hid behind Xing'er in fright and stammered in a whisper.

"I said I wanted to call my brother!" Apricot hurriedly advised.

Chen Xu's face was a little dark, Yu Ji is now calling Yu Wuya's father, and she is calling Yu Wuya's eldest brother, Xing'er is calling her brother, Yu Ji originally called her uncle is no problem, but calling her brother is in chaos, but Xing'er is happy to ask Yu Ji to call her brother and brother, because she feels that she is about the same age as Yu Ji, but since then, the generations in the whole family are all in chaos, because Yu Wuya still calls Chen Jiang as her sister-in-law, Xing'er also calls Sister Shui Qing, and Shui Qingrou and Yu Wuya are senior brothers and sisters, Therefore, the title of Chen Xu's family is completely messy now.

"Brother Xu, my sister and I didn't do anything!" Yu Ji quickly changed her tune.

"Really?" Chen Xu didn't believe it, mainly because there were too many unknown ores and materials in the laboratory, some of which were definitely poisonous, and the colors were also colorful and beautiful.

"Really!" The two little girls nodded vigorously together.

"Don't lie, a lot of things in the lab are poisonous and can't be eaten, and you don't say that you are not allowed to eat tomorrow!" Chen Xu's eyes became very serious.

"Brother Xu, don't skip the meal, I want to eat delicious beef noodles!" Yu Ji grabbed Xing'er's clothes tightly, and poked her head out with a deflated mouth and cried.

"Brother, we didn't ...... I didn't steal it, but I accidentally found that the white powder in the bamboo tube would have a beautiful purple flame when thrown into the stove! Xing'er also felt that Chen Xu was serious, and handed Chen Xu a bamboo tube in her arms with some fear.

"White powder?" Chen Xu took the bamboo tube with a puzzled face, opened it, and it was indeed some white powder with mud, and at the same time remembered that this bamboo tube was obtained from the cave where Yu Wuya went to the Wild Wolf Valley to put wine last time, and thought it was gypsum or brine crystals, but it turned out to be not, so he kept throwing it in the corner he didn't know, just now he thought that the bamboo tube that Xing'er took was candy, so he didn't think too much.

"Purple flames?" Chen Xu was suddenly stunned when he closed the lid, and at the same time, there seemed to be a lightning bolt in his mind that swept across the dark night sky, and he couldn't help but exclaim: "Flame color reaction~"

Chen Xu instantly remembered one of the simplest chemistry experiments he had learned in high school chemistry class, which could distinguish some common metal compounds according to the different colors of metal ions burned in flames.

"Yes, Brother Xu, it's purple, but it's beautiful!" Yu Ji whispered a little timidly, and there was still a tear on her face.

What metal ion is violet?

Although Chen Xu has done chemical experiments on flame color reactions, after all, several years have passed, and suddenly when he thinks about it, he feels that his brain is not enough.

But since the two little girls said it was purple, he naturally wanted to verify it.

The small stove in the laboratory is a block of coal, and a lid is made of yellow mud on it, usually covered to make the coal burn as slowly as possible, just to make the laboratory warmer, and sometimes Chen Xu needs to heat something that can be used at any time, but now the yellow mud cover on it has been opened by the two little girls.

Chen Xu poured out some white powder and threw it directly into the stove, and a purple smoke came out of the coal fire.

"Brother Xu, do you see it, Sister Xing'er and I didn't lie!" Yu Ji suddenly excitedly pointed to the stove with her little finger and shouted.

"Xing'er, take Yu Ji to the living room to play, don't come in the laboratory without my permission in the future!" Chen Xu waved his hand and asked Xing'er to take Yu Ji away.

"What kind of metal is purple?"

After the two little girls left, Chen Xu threw some white powder into the coal stove, looked at the burning purple smoke and slightly pungent smell, pinched his chin and began to rack his brains to recall the experiment of the flame reaction in high school.

Flame color reaction, is the color of various metal ions burned in the flame, but not all metal ions can be observed, high school chemistry class has done several experiments, that is, a variety of mineral salts or oxide powders stick to the wire or glass rod under the alcohol lamp to observe, so as to roughly identify the types of metal ions contained in the compound.

The sodium ion is yellow, which Chen Xu remembers best, because after taking a chemistry laboratory class, he also stole half a bag of pure salt for the laboratory test.

Magnesium is white, and this principle is used in the magnesium lamps used in old cameras, which can be easily recalled, and the others are still slightly remembered, but not too clear.

Chen Xu sat in front of the window and reminisced for a long time before picking up the brush.

The sky was getting darker and darker, and the room was getting darker and darker, but after about half an hour passed, Chen Xu also wrote several metals on the paper that could think of the flame color reaction.

Sodium: Yellow, Copper: Green, Magnesium: White, Calcium: Red, Cobalt: Blue.

These are the most common, such as copper ions, copper is green after oxidation, which is also the origin of bronze, copper ions are green whether they are burned or aqueous solutions.

Cobalt is used a lot in the glass industry, and the common cobalt glass is blue, and when observing the flame color reaction, each student sent a blue cobalt glass sheet.

Cobalt glass piece, Chen Xu suddenly remembered one thing, if I remember correctly, this purple should be potassium ions, because thinking of cobalt glass, the teacher also specifically mentioned at that time that the flame reaction of potassium ions is best observed after filtering through cobalt glass, because sodium salt and potassium salt are often mixed together, and cobalt glass can filter the yellow color of sodium ions.

And this tube of white powder burns directly into a very rich purple color, so it can basically be concluded that this is a very pure potassium salt.

Chen Xu was excited and had a headache at the same time.

Is it potassium nitrate or potassium carbonate or potassium sulfate, potassium phosphate or potassium chloride?

After thinking about it for a long time, he suddenly remembered that the temperature in the cave was very low, more than 30 degrees outside and only more than 10 degrees inside in summer, and the water was extremely cold.

Chen Xu's cheek couldn't help but twitch a few times, and he quickly found a cup filled with half a cup of water, put his fingers in it and felt it, and then poured some white powder into it, and soon, he didn't need to reach in to feel that the pottery cup was getting colder and colder.

This change gave him the only answer in his mind, that is, potassium nitrate, among the potassium salts, only potassium nitrate will absorb heat when dissolved, causing the water temperature to drop.