Ancient people didn’t understand things like functional environmentally friendly materials containing dozens of minerals and trace elements such as sodium, magnesium, aluminum, silicon, calcium, titanium, manganese, iron, nickel, cobalt, and molybdenum. However, they knew that only this kind of volcanic rock could conduct and dissipate heat. Only this kind of stone could dissipate heat through the stone when water was poured on it, and some of the water would form a large amount of water vapor after being heated.

　　The more water you pour, the higher the temperature becomes, and the more water vapor will be produced.

　　At the same time, the placement of volcanic rocks is also regulated so as not to obstruct airflow, in order to generate appropriate heat and water vapor.

　　If things are placed haphazardly, it can cause poor air circulation and prevent heat from dissipating, which can easily lead to accidents. Such incidents have happened before. Therefore, those who are wealthy hire businesses under the Zhang family for design and production, and even have the maids in the mansion receive relevant training.

　　Although such kitchen maids work very hard and are very tired, their monthly salary is much higher than that of ordinary maids, and their status is also high. They can even enjoy the special treatment that only masters, mistresses, young ladies and young masters can enjoy, so they are still very sought after.

　　Whether one is doing well or not mainly depends on what kind of person their master is.

　　As soon as Zhang Weihao came in, he heard Jiang Yuyan and the others talking about this. Zhang Weihao, who was also wearing a white bathrobe, found an empty seat and sat down and said, “There are volcanoes in China, but they are not active. The most active ones are in Japan and Southeast Asia, where volcanoes erupt from time to time.”

　　”This isn’t like going down into a volcano to retrieve it—that would be suicide, and it’d be incredibly difficult to take it away anyway. We go to areas that have experienced volcanic eruptions to collect it specifically, with strict selection criteria. Therefore, once the price is controlled within a certain range, many powerful families are unwilling to directly deal with the upstream source, focusing instead on downstream channels. It’s more cost-effective for them to buy directly from the Zhang family.”

　　The main reasons for this are related to sales scale and sales channels. If you can’t increase your scale and your purchase volume is not large enough, the cost will be very high and it will be difficult to sell.

　　At the same price, most powerful families would definitely prefer to cooperate with the Zhang family. As for the royal family… sorry, according to ancestral teachings, they cannot touch any business involving maritime transport. As soon as they open their mouths, all those beasts in the court will try to dissuade them in various ways. Some officials and censors will even directly smash their heads against the pillars of the court to remonstrate.

　　The emperor was most afraid of this, as it would definitely be recorded in history books and he would bear a bad reputation. So when faced with such a situation, even if he knew the tricks behind it, he could only grit his teeth and accept it.

　　As for the officials who dared to remonstrate, if they didn’t die, they would be promoted and become wealthy; if they died, their families would receive a fortune, and they themselves would be remembered in history.

　　The Zhang family was naturally one of them, and one of the biggest and most audacious. In this era, there was no commercial tax, so whatever they earned went straight into their own pockets. They would do this kind of business even if it meant risking their lives or rebelling. Anyone who tried to stop them, even if they were the emperor, would only be sent to their death.

　　In the mid-to-late Ming Dynasty, emperors could be incompetent, foolish, or neglect their duties, but there were two things they couldn’t do: open up the seas and implement reforms.

　　The ancestral laws cannot be changed, and the current political structure of governing by civil officials and military officials cannot be altered. The sea cannot be opened; anyone who proposes it will die. Who cares if you are the emperor or not? Several emperors who died mysteriously later were related to these kinds of troubles.

　　As the biggest beneficiary of the existing system, and since he wasn’t there to carry out any feudal dynasty reforms, Zhang Weihao couldn’t be bothered with these trivial matters. The Mingzong World was just a beginner’s village to him.

　　Of course, if Zhang Weihao were the reincarnation of Zhu Houzhao, then it would be different.

　　They must be severely punished, and each family must be thoroughly investigated. Even if every family is slaughtered, there will still be some who escape. If all the beasts in the court are killed, most of them will not be unjustly punished.

　　”Are you sure you don’t need to take your clothes off?”

　　”No need. The sauna suits are specially made and have good breathability. You don’t have to take them off. Of course, if you want to take them off, we won’t stop you. But we would like to remind you that it is easy to burn your skin if you take your clothes off and stay in the sauna for a long time.”

　　The main issue is technology. This primitive, human-powered heater is certainly not as convenient as the ones used in later times. It’s better to control the duration while wearing clothes.

　　”Hmm, it feels so good to work up a sweat. You really know how to enjoy yourself. By the way, can we do this at our Yihua Palace?”

　　”Sure, but it’s not very meaningful if the weather is good. It’s not good for cultivating the Mingyu Gong, otherwise your master would have done it long ago.”

　　”What! It will affect Mingyu Gong’s cultivation? Why didn’t you say so sooner!”

　　Seeing Jiang Yuyan’s amusingly nervous expression, Zhang Weihao moved directly to her side, put his hand inside her clothes and started playing with her breasts, saying, “It’s not too late to say this now. It’s not like this happens every day. A few times won’t have much of an impact. You’re really quite naughty. Your nipples got hard right away. You can’t take teasing.”

　　”How dare you say that to me? I’m in this state because of you. By the way, is it okay to do it here?” Jiang Yuyan licked her lower lip excitedly, clearly tempted to try it out in this sauna room and see how it differed from doing it in the carriage.

　　“Sure, but the way we play is different. Let Qianxun demonstrate for you.” Zhang Weihao kneaded Jiang Yuyan’s nipples and kept pulling on them.

　　Xue Qianxun understood and stretched out the massage bed that had been folded up. Then she asked Lan Jian to bring over the special stall, towels, and some essential oil tools.

　　After everything was ready, Zhang Weihao lay down directly on the wooden folding massage bed.

　　Xue Qianxun took off her clothes and went to Zhang Weihao’s side. She applied some essential oil to her hands and started applying it directly to the naked Zhang Weihao.

　　Gradually, Xue Qianxun focused her hands primarily on Zhang Weihao’s chest, applying acupressure massage there. Only then did she move on to his arms and shoulders.

　　Just when Jiang Yuyan thought that was the end of it, something exciting happened.

　　Xue Qianxun poured some unknown substance, which looked like cooking oil, directly onto her body. Then she climbed onto Zhang Weihao, using her hands for support, rubbing her breasts against his body. She spread her legs and mounted him, her vagina constantly brushing against his penis.