Chapter 52

Hearing that Zhou Chong finally remembered to prepare a return gift for her, Zhuo'er was also very pleased and said, "That's great! I've been thinking about how to return a gift to Lingyun Sister these past few days. I thought you had forgotten about it, but I didn't expect you to still remember."

Seeing Zhuo'er's happy expression, Zhou Chong affectionately pinched her small nose and said, "How could Brother forget what he promised to Zhuo'er? This afternoon, I'll buy all the materials. It shouldn't take long to make, and the process of making this gift is very interesting. You and Duo'er can watch then!"

Duo'er, who had been playing with Zhou Chong's brush and ink on the table, immediately reacted when she heard her name and the word "gift." She said, "I know, I know! Brother hid Sister's gift under the quilt!"

"Phew~" Zhou Chong almost spat out a mouthful of blood. He thought, kids are unreliable. It hadn't been long, and she had already forgotten their previous agreement.

"Gift, what gift? Why did you hide it under the quilt, Brother?" Zhuo'er was also puzzled by Duo'er's words. She walked to the bed and tried to pull the tangled quilt.

Seeing the manuscript of "Jin Ping Mei" about to be discovered, Zhou Chong leaped onto the bed and turned to Zhuo'er with a grin, "There's no gift. Don't listen to what Duo'er says!" Zhou Chong glared at Duo'er, who realized her mistake and stuck out her cute little tongue, then ran out to play with Baiqiu.

Zhuo'er's curiosity was further piqued by Zhou Chong's reaction. She tugged at the quilt, determined to see what was hidden underneath. Zhou Chong, of course, couldn't let her succeed, so he pressed down on the quilt with his body, and the two struggled for a while.

Zhuo'er, after all, was just a fourteen-year-old girl, and she soon became breathless and her strength waned. Seizing the opportunity, Zhou Chong grabbed her small hand and said, "Auntie should have finished making lunch. Let's go eat quickly!"

Although Zhuo'er was unwilling, she had no strength to resist and could only pout as Zhou Chong pulled her out of the courtyard. To prevent Zhuo'er from sneaking back, Zhou Chong locked the courtyard gate for the first time, which made Zhuo'er even more unhappy.

After lunch, Zhou Chong and Manager Xu went out with a cart. Originally, buying flour only required one person, but Zhou Chong didn't know the location of the grain and oil shop. Manager Xu knew, but he was old, and Wu Shan was bedridden and couldn't help. Additionally, Zhou Chong needed to buy materials for the gift, which he couldn't carry alone, so they went together.

Soon, Zhou Chong followed Manager Xu to the grain and oil shop and bought a large bag of flour, which cost nearly two fen of silver. If it were the same weight of rice, it would have cost only one-third of that, showing how expensive flour was in the south.

In addition to flour, Zhou Chong also bought a large jar of oil. The shop sold various types of oil, both animal and plant-based. Zhou Chong bought the most common and cheapest rapeseed oil, over fifty pounds. Manager Xu complained, first because there was still some oil at home, and second because he thought Zhou Chong had bought too much, which the family wouldn't use up for a while. However, Zhou Chong just smiled without explaining, as he wasn't buying the oil for consumption.

After buying the flour and rapeseed oil, Zhou Chong was surprised to find that the shop also sold soda ash (sodium carbonate). It made sense, as soda ash was used in making flour-based foods, so it was normal for the shop to sell it. This saved Zhou Chong the trouble of looking elsewhere. Unfortunately, soda ash wasn't used much in cooking, so the shop didn't stock much. Zhou Chong bought all twenty pounds of it.

After loading everything onto the cart, Zhou Chong asked Manager Xu to take him to a place selling lime, where he bought a large bag of quicklime. They returned home fully loaded. Manager Xu noticed something was off and kept asking Zhou Chong about the purpose of these items, but Zhou Chong remained mysterious and didn't explain.

Back home, Zhou Chong pushed the cart to his courtyard. He had Manager Xu deliver the flour to the kitchen, but kept the other items. He then fetched a large pot and several water jars from the kitchen, as well as a large-mouthed porcelain bottle.

Just as Zhou Chong was transporting these items to his courtyard, Zhuo'er and Duo'er ran over. Zhuo'er, seeing the items Zhou Chong had brought and the oil jars and quicklime scattered around, couldn't help but ask, "Brother, are these the materials you're preparing for the gift?"

"Exactly!" Zhou Chong put down a large jar, wiped his sweat, and smiled, "Today, Brother will perform a magic trick for you, using these seemingly unrelated materials to create something you can't even imagine!"

"Great, great! Duo'er loves watching magic tricks!" Little Duo'er, who always believed Zhou Chong, jumped up and clapped her hands in excitement. However, Zhuo'er was skeptical. She couldn't imagine what good gift could be made from these ordinary items.

Zhou Chong noticed Zhuo'er's doubt but didn't explain. Actions speak louder than words. Once he made the item, Zhuo'er would understand that her brother wasn't exaggerating. First, Zhou Chong put the quicklime into a jar and poured water over it. Soon, the jar began to bubble and steam.

Quicklime is calcium oxide, which reacts with water to form calcium hydroxide. After the chemical reaction in the jar was complete, Zhou Chong added the soda ash and gently stirred to ensure the calcium hydroxide and sodium carbonate reacted fully. Zhuo'er came over to help, but Zhou Chong didn't let her stir, as the resulting sodium hydroxide, also known as caustic soda, is a highly corrosive strong alkali. If it splashed on the skin, it could burn through the flesh.

As Zhou Chong stirred, the reaction in the solution accelerated. The insoluble calcium carbonate precipitated, and the sodium hydroxide solution remained on top. Sodium hydroxide easily absorbs carbon dioxide from the air and turns into sodium carbonate, so Zhou Chong poured the sodium hydroxide solution into a large porcelain bottle and sealed it with a lid and cotton cloth. This didn't completely prevent carbon dioxide from entering, but it was better than leaving it open.

Seeing Zhou Chong handle the caustic soda solution so carefully, Duo'er, who had been tilting her head in silence, finally asked, "Brother, what did you put in the bottle? Is it tasty?"

Zhou Chong laughed and said, "This is called caustic soda solution, a highly toxic substance. Don't even think about drinking it. If it splashes on your skin, it can burn through the flesh. So, Duo'er and Zhuo'er, don't touch it!"

Hearing Zhou Chong's warning, Zhuo'er was startled and then worriedly said, "Brother, since this caustic soda is so dangerous, don't touch it. What if you hurt yourself?"

"Don't worry, Brother isn't a child. Although caustic soda can be dangerous, it's also very useful. I'm about to use it to perform a magic trick for you!" Zhou Chong said nonchalantly. With caustic soda and oil, he could make soap in the Ming Dynasty. The uses of soap were well-known, and since he was the only one who knew how to make it, it would be a great gift, not inferior to Xie Lingyun's cosmetics.

In ancient times, ordinary people usually used soap nuts for washing hands, faces, and clothes. Some merchants ground soap nuts into powder and sold it as soap nut powder, but its cleaning power was weak, especially for oil stains.

Besides soap nuts, there were also soaps made from pig pancreas and various fragrances, but these were expensive and had limited raw materials, so they were only used by wealthy families for washing faces and baths. Zhou Chong's family had a bit of leftover soap, which looked black and unappealing but had strong cleaning power, not inferior to soap. However, it was very expensive, with a small piece costing over ten taels of silver, making it a luxury item in ancient society.

After making the caustic soda solution, Zhou Chong dug a small stove on the ground with a shovel, placed a large iron pot on it, and brought some firewood from the kitchen to light it. After cleaning the pot, he poured in the caustic soda solution and oil. Since there was more oil, he only poured in part of it and stirred continuously with a stick.

Initially, the caustic soda solution and oil were clearly separated into two layers. However, as the mixture heated and Zhou Chong stirred, the oil layer gradually decreased and eventually disappeared. Zhuo'er and Duo'er stared wide-eyed, unable to believe what they were seeing. They couldn't fathom how the oil in the pot could disappear.

This saponification reaction was not magical; it was simply a chemical reaction between a strong alkali and fat, which could be learned in high school chemistry and easily DIYed at home.

However, Zhou Chong didn't stop there. He was concerned that the caustic soda in the solution hadn't fully reacted, so he kept adding oil bit by bit until the added oil no longer disappeared. Then he stopped and extinguished the fire.

Zhou Chong then took salt from the kitchen and turned to the stunned Zhuo'er and Duo'er, saying, "Pay attention, girls. Brother is about to perform a magic trick!"

Hearing Zhou Chong's words, Zhuo'er and Duo'er, already amazed by his series of "magical" skills, widened their eyes even more, staring intently at the steaming "clear broth" in the iron pot.