Tao Hongjing (456-536), with a bright word, lived in seclusion in Huayang in his later years. Posthumous title Bai Zhen, a famous Taoist thinker and pharmacologist, was born in Liling, Danyang (now Nanjing, Jiangsu) in the Southern Dynasties. Grandfather Long Tao and father Tao Zhen are junior officials. He was studious all his life, loved writing, was knowledgeable and dabbled in a wide range, and had high attainments in literature, religion, medicine, Confucian classics, astronomy and astronomical calendar, which had a great influence on later generations. After Tao Hongjing lived in seclusion, he wrote Notes on Materia Medica, True Letters, True Spirit Map, Tao's Good Prescription, Hundred Prescriptions for Elbow Repair, Tao's Living in Seclusion Materia Medica, and Yaotongfang. Looking at his academic achievements, it is not difficult to see that Tao Hongjing is a scholar influenced by southern culture.

Tao Hongjing "is a modest person (circle), and when he goes out, he is like a mirror, and it is convenient when he meets something." If you don't worry about what you say, you will feel it when you have it. This is an open-minded, quick-thinking and receptive talent. Hongjing when he was young was diligent and knowledgeable. At the age of ten, he read Ge Hong's Biography of Immortals and decided to keep fit. Moreover, his spirit of studying hard is very touching. The history books say that he "read more than 10,000 volumes and is shameless". Tao Hongjing's high talent and hard-working attitude are important conditions for him to become a great scholar. As a teenager, Hongjing was proficient in calligraphy and familiar with medical books. When he was young, he was called into the palace by Xiao Daocheng, then prime minister, and Qi Gaudi, later emperor, and became a servant among kings. At the age of 37, he resigned from his official position and returned to Maoshan, Jiangsu Province to live in seclusion, specializing in alchemy and writing articles. Liang Wudi knew Tao Hongjing in his early years. After he proclaimed himself emperor, he wanted him to be an official and assist in state affairs. Tao Hongjing then drew two cows, one grazing freely, the other with a golden halter, led by a whip. Liang Wudi knew what it meant as soon as he saw it. Although he was not an official, Liang Wudi and Tao Hongjing kept writing about Tao Hongjing's portrait, especially some national affairs. Liang Wudi will ask Tao Zhenren for advice first. Therefore, some people call Tao Zhenren "the Prime Minister in the Mountain".

But why did Tao Hongjing devote himself to the cause of alchemy in his later years? According to historical records, Xiao Yan of Liang Wudi at that time also pursued immortality like Emperor Wu of Han Dynasty, so he asked Tao Hongjing, the Taoist priest at that time, to make an alchemy for him. On the one hand, it is to realize the dream of "immortality", on the other hand, it is also to let the people and ministers know that Tao Zhenren is not his own mentor, but the emperor's own servant. At first, Tao Hongjing refused to be an alchemist on the pretext of not learning from Li (when Emperor Wu of the Han Dynasty was an alchemist, he would live forever), but he repeatedly persuaded him with "dreams". But he can only promise, and Tao Hongjing had long planned to live in seclusion, away from official grievances, so Tao Hongjing took this opportunity to let himself live in seclusion in the mountains. Tao Hongjing is a serious person. If he doesn't do it, he will do it seriously. So he moved to Maoshan Jijinling to concentrate on the cause of alchemy, and set up Huayang Shangge and Huayang Xiage in the west of the ridge. Huayang's upper pavilion is used for studying and writing articles, while the lower pavilion is used for alchemy.

Between the ages of 50 and 70, Tao Hongjing experienced seven times of alchemy. Although he is serious and rigorous, he is always skeptical about alchemy. Therefore, Tao Hongjing attached importance to some achievements in alchemy, such as prescriptions for treating patients such as mercury, mirabilite, realgar and salt, and methods and technologies of early chemical pharmacy. All of these were written into his famous medical book "A Hundred Prescriptions after the Elbow is Full". This book embodies a remarkable feature of Dow's alchemy, that is, he did not insist on pursuing the "panacea" of "becoming immortal", but promoted the development of primitive chemical pharmacy intentionally or unintentionally through the initial confluence of alchemy.

Tao Hongjing's alchemy for nearly 20 years has made great contributions not only in chemistry and pharmacy, but also in ancient chemistry in China. There are two main aspects: first, in the aspect of mercury (mercury) alloy (amalgam), he pointed out the difference between artificial crude mercury and natural pure silver. Tao Hongjing said, "Mercury is ripe today. This cloud is born in the belly of cinnabar; There are also those who stay in the sand, blue and white, the best; The cinnabar comes from burning coarse cinnabar today, and the color is small and white, not much. " Tao Hongjing put forward more clearly that mercury can be alloyed with gold and silver, and can be plated with gold and silver. Secondly, in terms of lead compounds, Tao Hongjing clearly pointed out that powdered tin "that is, modern lead-made Hu fen" and plumbum preparatium "that is, gold and aluminum" are all artificially made. And Tao Hongjing's biggest discovery is to know the identification of saltpeter. The ancients often could not distinguish potassium nitrate from sodium sulfate, which were generally called "saltpeter", "mirabilite" and "mirabilite". Tao Hongjing found a way to distinguish them. He said that burning these two substances shows that the purple-blue flame is the characteristic of potassium salt, while the flame of sodium salt burning is yellow. Tao Hongjing's method and discovery of detecting saltpeter made China the first country in the world to extract, identify and utilize saltpeter, which created conditions for the later invention of gunpowder.

Tao Hongjing has not only made great achievements in the field of chemistry, but also made great contributions to China in metalworking and mechanical technology. In metal, he was the first person to record the smelting method of steel casting. He has a special interest in swords. He wrote Records of Ancient and Modern Swords, describing the names, sizes and inscriptions of famous swords from Xia and Shang Dynasties to Liang Wudi. He said, "Steel is a sword and a sickle." "Raw" is pig iron and "soft" is wrought iron. The method of pouring pig iron into wrought iron for "miscellaneous smelting" is the steel casting method. In mechanical technology, Tao Hongjing's "to make twelve rounds of circulation, because the running water naturally leaks, it is not necessary to follow the rules, and the water in the mountain stream is easy to scale and uneven, so it is not established", which is a mechanical technical problem that challenges the ancient timing device. Although the plan of this waterwheel clock is not successful, his creative spirit is worth learning.

Tao Hongjing is also the founder of Maoshan School, a Taoist Shangqing school. In addition to his remarkable achievements in the above aspects, he mainly collected, sorted out and summarized the previous health care experiences and thoughts, "laying a theoretical foundation for Taoism to finally form a medical health care model that pays equal attention to cultivation and life care (nourishing the heart, shaping and integrating body and mind), combining static and dynamic, and combining various techniques."