# 31. It's Not Free; It's Equivalent Exchange "The crux?" Song Qing ruminated and analysed based on the experience of previous failures and the current success. The previous steps hadn't changed, the real change was in the final step: the lightning strike! How was the lightning different than the previous attempts? Some faint currents ran in his mind as Song Qing's body shook, and he said excitedly, "I understand, I understand." "Xu Ningyan, you indeed have extraordinary talent in alchemy." "Although you hadn't seen our previous experiments, You had already deduced it, right? You knew the real reason for our failure already." *No, I only know that you have been thinking big…* Xu Qi'an smiled and didn't say anything. "What's the crux? What did you understand, brother Song?" "Don't keep up the suspense, Senior Brother Song. Tell me quickly. This alchemy has almost become my obsession." The alchemists in white asked anxiously. Song Qing coughed, looked around at his juniors, and said deeply, "It's the intensity of a lightning strike." After speaking, he looked at Xu Qi'an, looking for his validation. Xu Qi'an nodded with a smile and said, "I call it electric voltage." The voltage required to electrolyze sodium metal should be controlled between 6-15 volts. Electric voltage? Song Qing was taken aback since it was a word he hadn't heard of before. He knew of electricity, but he had never heard of electric voltage. Instinctively, he felt that it was an important piece of knowledge, as profound as the knowledge in the blue book. A white-cloaked alchemist took a step forward and bowed to Xu Qi'an, "Brother, can you please explain what voltage is?" "Please teach us." The other white-cloaked alchemists cupped their hands simultaneously and said in unison. Chu Caiwei, who was standing aside, was very envious. She liked the feeling of being a master and teaching apprentices the most. It was a pity that she was only a Master of Feng Shui and wasn't qualified to teach apprentices. *Electric Voltage, also known as electric pressure, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to move a test charge between the two points. Of course, You wouldn't understand this.* Xu Qi'an coughed, and said seriously: "Electricity is the same as flowing water, it will flow towards the lowest point." He raised a teacup and poured water into it, "It's okay to pour this cup on anyone, but if it's a waterfall, people will be injured due to the impact of the water or could even lose their lives. So, I call this phenomenon electric pressure ,or voltage. He used this simple example to explain voltage. The Sitianjian's White cloaks frowned and fell into deep thought. They couldn't understand the words of Xu Qi'an well. Although they were alchemists and could manipulate lightning, it didn't mean that they understood the nature of electricity. Song Qing suddenly understood something, and raised a point, "So, the reason why thunder and lightning hit trees on rainy days is that the trees are at the low point. It should be the same for people. Additionally, we'll only feel paralyzed for some time if the current is weak, but if one were to be hit by lightning, then they would die." "The truth is that the voltage of natural thunder is so strong that it exceeds the limit that ordinary people could bear, just like a waterfall. The weak current is like a cup of water, which can be withstood by the body." The alchemists were suddenly enlightened due to the words of Song Qing, and felt excited to have obtained a profound truth. They looked at Xu Qi'an for validation. *Um, is this the principle? Isn't the reason for trees being struck by lightning the conductivity of rainwater? My middle school teacher hadn't made it clear…* Xu Qi'an wasn't sure himself, so he said smilingly, "You can understand." "Was this also written in the alchemy tome?" A young white cloak asked with a curious face. "Yes, I'm the only one who has learned the contents of the alchemy book. The content of the notes I'd sent to Sitianjian was just a drop in the ocean." After a pause, Xu Qi'an said deeply. "That ancient alchemy book not only recorded knowledge, but many rare alchemy techniques." News of rare alchemy techniques made everyone breathe heavily. Xu Qi'an smiled, and made a promise that made the white cloaks excited, "I've decided to share the tome of alchemy with Sitianjian." Woah! Nearly twenty alchemists became excited over his words. "The blue book I gave to Sitianjian was a thank-you gift for saving me. The complete knowledge for refining fake silver and the knowledge of voltage isn't free.", Xu Qi'an said. "Of course, The paid content also includes the follow-up alchemy secrets." "Never forget that the principle of alchemy is equivalent exchange!" Song Qing nodded, since he agreed with Xu Ningyan's reasoning, and asked questions on behalf of his juniors. "How much silver do you want?" "Vulgar!" Xu Qi'an said deeply, "How could Alchemy be measured by mere silver." *Free is the most Expensive*, He added silently in his mind. … Changle County Office, Side Hall: Xu Lingyue held her sleeping young sister in her arms, holding a handkerchief while crying. The bailiffs in the office were heartbroken looking at her tear-stained face. They never expected that Xu Ningyan had such a pretty younger sister. Even Constable Wang, who frequented the Jiaofangsi was amazed by her beauty. The atmosphere in the side hall was a melancholy, and the bailiffs looked listless. Constable Wang poured a cup of tea and placed it in front of Xu Lingyue. The little beauty had cried for a long time, and tears had continuously flowed from her eyes. Women were indeed made up of water. "Miss Xu, don't worry, Lord Baihu will find a way to rescue Ningyan." The other bailiffs comforted her and scolded Young Master Zhou. *Elder Brother has a good relationship with his colleagues…* Xu Lingyue was a little surprised that the angry expression of the bailiffs wasn't fake. As if he saw her surprise, Constable Wang smiled," Ningyan is a person worthy of being respected." Respected? Xu Lingyue was stunned and after sobbing for a while, said softly, "Constable Wang, Can you tell me about my elder brother?" Constable Wang was silent for a while, and subconsciously lowered his voice, "Actually, how could people like us have clean hands?" "If you didn’t attack common people, then you’d already have a good conscience. As for those wealthy businessmen, isn't it normal to seek profit from them?" "But your elder brother couldn't do it, whether it's a commoner or a wealthy business, he never extorted or blackmailed them. A while ago, considering the catastrophe of the Xu family, I decided to take him to make a fortune." Constable Wang was a bit embarrassed when talking about this matter. "He agreed with the matter. Later, I gave him five cash of silver but he quietly returned it to the other party." “If you say that he’s well-behaved, well, I’m sure he knows the principle that there are no fish in clear water. But to say that he’s not, he’s very good at dealing with matters, and has a good relationship with everyone. He’s very slippery. So if something happens to him, we’re all upset.” e has a good relationship with everyone and is very slippery. So, his arrest made everyone sad." Xu Lingyue listened attentively, and the image of her elder brother in her mind became taller, brighter, and stalwart. She admired Xu Xinnian since her childhood, because everything aside from studying was vain, because her mother had instilled in her that her second brother was the only person suited to study in the Xu family, and he will be the pillar of the family in the future. This admiration reached its peak in the autumn of this year when Xu Xinnian passed the exam. But, during the tax fraud case, when the entire family was imprisoned, and when they were desperate and helpless, the Elder brother opened up a way out for the entire family in that desperate situation. Her attention was drawn to her elder brother and she became curious about him. Until today, She didn't know the reliability of her big brother even if he had rescued them from prison a month ago. The feeling back then was not as deep as this time. At the moment when her elder brother rescued her little sister, Xu Lingyue felt that the image of her elder brother in her heart was equal to her second brother's. At the moment, hearing Constable Wang's description, the image of a high-spirited, principled person with a bottom line emerged in her heart and exceeded the status of the second brother she'd always admired. Then, the light in the entrance changed, and Xu Pingzhi and his son finally rushed back to Changle County Office. When they saw their sister (daughter) safe and sound, Father and son were relieved. Xu Lingyue raised her head, with tears flowing down her face, and sadly said, "Father, you have to save big brother. If big brother doesn't come back, your daughter won’t have the will to live."