Chapter 4 Chapter 2 Chemical Achievements in Ancient Chinese Metallurgy

More than 30 bronze wares, including knives, cones, chisels, rings, etc., were unearthed in the Qijia culture (about 4000-4500 years ago) site of Wuwei Huangniangniangtai, Gansu Province. After chemical analysis, the purity reached more than 99.6%. The presence of slag, with only traces of tin, lead, antimony, nickel, indicates that they were forged or cast from native copper.In Dahezhuang and Qinweijia cultural relics in Gansu Province, some small bronze wares were also found, which contained about 5% lead; There is an obvious amount of tin and a small amount of lead; a copper cone was unearthed at the Longshan cultural site in Jiaoxian County, Shandong Province, and it was actually a copper-zinc alloy containing a small amount of lead and tin, with a zinc content of 20-26%.There is no doubt that these copper objects were smelted from copper ore.In particular, in 1958, at the Xindian Cultural Site in Zhangjiazui, Yongqing County, Gansu Province, and at the Longshan Cultural Site in Zhucheng, Shandong Province, not only red bronze ware fragments, but also copper slag and malachite were unearthed; Remnants of copper smelting crucibles were unearthed from late sites, with red copper particles attached to them, so it can be confirmed that copper was smelted in these areas at least 4,000 years ago.Malachite was undoubtedly the first to be smelted. When excavating the Yinxu site in Anyang, Henan in 1929, a large piece of malachite weighing 18.8 kilograms was obtained, and its unearthed site was in an area densely populated with copper smelting sites.The first vessels for copper smelting were helmet-like pottery crucibles, which are now called "general helmets". The general capacity is about three liters, which can hold 5-10 kilograms of ore. They have been unearthed in Anyang and Linzi, Shandong.When smelting, put ore and charcoal into it and heat it on a charcoal fire or in a furnace similar to a pottery kiln.Some unearthed crucible pieces still have small holes. Metallurgical historians estimate that pottery pipes were installed at that time, and air was blown through the mouth to help the combustion and heat up.

Because copper is soft, it is neither suitable for making tools nor weapons.Later, it was accidentally discovered that the alloy produced by combining red copper or copper ore with tin ore and lead ore—bronze is much harder and tougher, and its melting point is also lowered (for example, when the tin ore is 25% The melting point is only 800°C), which is more convenient for smelting and casting.So people gradually consciously smelted bronze. In 1975, bronze knives were unearthed at the Majiayao cultural site in Dongxiang, Gansu and the Machang cultural site in Jiangjiaping, Liancheng, Yongdeng County, Gansu, indicating that bronze was smelted in these areas as early as 4,000-4,500 years ago.In the early Shang Dynasty, bronze wares became more common. Among the early bronze wares unearthed in Erlitou, Yanshi, Henan in 1974, there were not only small knives, adzes, chisels, arrowheads, jue, fishhooks, etc., but also relatively large objects such as square tripods, which shows that our country was equivalent to the end of the Xia Dynasty in the Central Plains. May begin to enter the Bronze Age.

The process of smelting bronze started from the combined smelting of red copper, tin and lead ore, and further developed to the separate smelting of red copper, tin and lead, and then mixed together for smelting. This is a development process from low-level to high-level.Obviously, this must wait until the smelting of metal lead and tin is successful, and there is a large-scale production.At present, the earliest metal lead wares are unearthed in Aohan Banner, Chifeng, Inner Mongolia. They belong to the lead shells (the earliest metal currency) and lead sheaths belonging to the lower culture of Xiajiadian, dating back 3500-4000 years ago.However, more lead burial objects, such as lead wine cups, lead pots, lead daggers, etc., only appeared in the Yin Ruins.It is said that tin blocks were also unearthed from the Yin Ruins in Anyang.Xige was unearthed in Da Sikong Village, but it belongs to a rather late period.Therefore, the circles of scientific history and archaeology estimate that my country began to gradually smelt bronze with lead and tin in the early Shang Dynasty.

The heyday of bronze smelting in my country was from the Shang Dynasty to the early Zhou Dynasty (the periods of Cheng, Kang, Zhao, and Mu kings), which is the typical slave society period in China.At that time, many large-scale bronze wares were cast, solemn and dignified, and most of them were decorated with Taotie (taotie Taotie Qu, the legendary gluttonous beast) face, dragon and phoenix. The "Simuwu" tripod unearthed in Wuguan Village, Anyang in 1939 is a representative work of bronzes of this period, and was cast by the king of Shang to commemorate his mother "Wu".Generally speaking, a tripod is used for cooking food, but this giant tripod may have been used as a national treasure.It has a weight of 875 kilograms, a height of 133 centimeters through the ear, a horizontal length of 110 centimeters and a width of 78 centimeters.If a "general helmet" or Dakouzun is used to melt bronze water for casting, forty or fifty such crucibles must be used at the same time.One can imagine the magnificence of the casting scene that day.After partial analysis of the feet of the tripod, it contains 84.8% copper, 11.6% tin and 2.8% lead.At that time, the casting process of bronze wares was also very exquisite, and the shape was beautiful. A four-goat statue was unearthed in Ningxiang, Hunan, which belonged to the late Shang Dynasty. The four corners of the belly of the statue were each cast with a sheep's head. There were curly horns on the head, and the shape was extremely beautiful. , with a complex structure, which fully embodies the superb skills of the casters of the Shang Dynasty.According to the research and judgment of metallurgical historians, not only the lost-wax casting method was invented in the Shang Dynasty, but also the separate casting method (joint casting method) has already taken various forms.

Large pieces of copper smelting slag were also found in the Yin Ruins, some weighing as much as 21.8 kg.Such a large amount of refining slag is no longer what the "general's helmet" can accommodate.At that time there probably had been a larger furnace, but the specific shape is unclear, because no relics have been found.The earliest known copper smelting shaft furnace is from the Tonglushan mining and smelting site in Daye, Hubei (where copper smelting began in the Western Zhou Dynasty), which is a relic of the late Spring and Autumn Period (Figure 2-1).It is roughly estimated that the shaft furnace is about 1.2-1.5 meters high and consists of a furnace base, a furnace cavity and a furnace body.The foundation of the furnace is rammed layer by layer with a mixture of clay and stones, and there are wind trenches inside.The cross-section of the furnace cavity is oval.Different parts of the shaft furnace were rammed with clay, kaolin, quartz sand, igneous rock chips, iron ore powder, and charcoal powder in layers;The lower part of the front wall of the furnace is equipped with a copper "golden gate", which is blocked during smelting.There are holes for slag discharge on it.There is a slightly downward-sloping ventilation ditch on each side of the furnace to blow air into the furnace.This structure is quite advanced, indicating that there have been quite a few years of experience in the use of smelting furnaces.According to the records of "Mozi", a blower made of cowhide had been invented at that time, and the name was "Pi Lu (tuo camel)".Someone once studied the copper smelting slag left over from the Tonglushan copper smelting area. The fluidity of the slag is quite good (indicating that the furnace temperature is quite high), and the average copper content is only 0.7%. It can be seen that the extraction rate is quite high, and the slag and copper are separated. Also good.Judging from the leftover ores, the raw materials used are mainly malachite type, but there are also cuprites (mainly composed of CuO); from the analysis of slag, it seems that iron ore was added as a co-solvent at that time. The origins of ironmaking are instructive.

Since when has copper sulfide ore (chalcocite, chalcopyrite, generally high in iron content) been widely used in my country?It is difficult to judge at present.Some plate-shaped copper ingots in the bronze wares in Guichi Warring States, Anhui, contain as much as 30% iron and about 2% sulfur; and recently, the ancient mining and smelting site of Linxi Dajing in the Chifeng area of ​​Inner Mongolia was discovered, which was earlier in the Spring and Autumn Period. In the early days, sulphide ores in which copper, tin and arsenic co-existed began to be smelted there.This shows that in the Spring and Autumn and Warring States periods of our country, some areas have tried sulfide ore.But the widespread use seems to be much later, because the use of this kind of ore needs to be oxidized and roasted first, and the process is complicated.

From the Shang Dynasty to the Warring States period, in addition to cooking utensils, eating utensils and sacrificial utensils (called Yi ware), more bronzes were used to make weapons and chariots. "Multiply" is also used to make production tools.In addition, it is also used to make bronze mirrors and musical instruments (such as bells, cymbals, and chimes).Due to the widespread use of bronze, people have gradually realized that there is a certain relationship between the ratio of copper to tin in bronze (there was not much distinction between lead and tin at that time) and its performance.In the Eastern Zhou Dynasty, a person from Qi State wrote a book called "Kao Gong Ji", in which there is a famous passage about the ratio of bronze.The original words are as follows:

"There are six equal parts of gold. Six parts are gold and tin is one, which is called the Qi of bells and tripods; five parts are gold and tin is one, which is called the Qi of ax and catty; four parts are gold and tin is one, which is called Ge The halberd is even; the gold is divided into three parts and the tin is in the first place, which is called the sharp edge; the gold is divided into five parts and the tin is in the second place, which is called the sharpness of cutting arrows; the gold and tin are half, which is called the sharpness of the fire. The meaning of the word "gold" in this text (except for the first word "gold" which definitely refers to bronze) is currently controversial in academic circles. Some people think it refers to bronze, while others think it refers to metallic copper.The so-called Liuqi (ji) refers to the six alloy formulas (qijiji, dosage).According to the first interpretation, the meaning of this passage is: the bronze used to make bells and tripods, of which tin accounts for 1/6; the bronze and tin used to make axes and machetes should account for 1/5.Others can be deduced by analogy.The so-called gold and tin half, that is, tin accounts for half of the bronze."Ge" in the article is a weapon for horizontal strikes and hook aids, "halberd" is a weapon that can be used for both horizontal strikes and straight stabs, "big edge" is a sword and the like, and "cut" is a knife for carving. "Jian" already refers to a mirror in the Warring States Period, and "Sui" refers to a concave mirror, which is used to gather sunlight to make fire.However, no matter how it is explained at present, this formula does not quite agree with the chemical analysis results of the actual bronze wares of the Eastern Zhou Dynasty, and it is not reasonable to evaluate with modern scientific knowledge, so further research is needed.However, people at that time were able to realize that different proportions of bronze have different properties, which are suitable for making utensils with different requirements, and they paid attention to summarizing the experience in this area and exploring its laws, which is very commendable.

After the Warring States period, a variety of coating techniques appeared in the production of bronzes, which are both beautiful and anti-corrosion.The most noble of these is of course gilt.Gold-plated chariot and horse decorations were unearthed from the Warring States Tomb in Fenshuiling, Changzhi County, Shanxi, and gold-plated belt hooks were unearthed from the Guan Chu Tomb in Changtai, Xinyang, Henan.This craft has been perfected by the Western Han Dynasty.The Changxin Palace Lantern unearthed from the tomb of Dou Wan, wife of Liu Sheng, King Zhongshan of the Western Han Dynasty in Mancheng, Hebei, the gilded bamboo incense burner of the Western Han Dynasty unearthed from the unnamed tomb of Maoling, and the gilded bronze horse unearthed from the Tomb of the Western Han Dynasty in Xingping County, Shaanxi. Layers are still shining brightly.The so-called gilt technique is to dissolve gold in mercury to make mud paste amalgam, apply it on the surface of bronze (or silver) utensils, and then heat and bake to make the mercury in it volatilize, that is, part of it penetrates into copper. Gold-plated layer in the tire.In addition to gilding, the technology of oxidizing bronzes into jet black was also invented in the early Warring States period to prevent rust or make flower decorations.At that time, the bronze mirrors made in Chu State often had a layer of lacquer-like coating, which is now called "black lacquer ancient".According to the records of "Huainanzi Xiuwu Xun", it was painted with "Xuanxi" and polished with white felt (called "consecration" in ancient times).According to scientific testing, "xuan tin" is tin amalgam, and "black lacquer ancient" is caused by the long-term oxidation of the tin layer on the surface of the copper mirror to form tin oxide.In addition, many bronze arrowheads (arrowheads) unearthed from the pottery pits of the Qinshihuang Mausoleum in Lintong, Shaanxi Province are as clean as new, still extremely sharp, and their surfaces are pitch-black or gray-black.According to scientific testing, it is a dense chromium-containing oxide film. According to simulation tests, it is speculated that the arrowhead may have been treated with a mixture of chromite, trona, and saltpeter at a high temperature, so this coating was obtained.Moreover, the Liu Sheng Saber unearthed from the Han Tombs in Mancheng has been stored for more than 2,000 years in the damp underground, but it is still bright, golden in color, and sharp as new.It is presumed to have been treated with sulfur or sulfide.In short, during that period, the craftsmen who made the bronze ware really spent a lot of effort in trying to beautify and protect the bronze ware, and it was also very effective.

After the Warring States period, my country's iron smelting industry rose and developed rapidly.By the time of the Qin and Han Dynasties, many bronze wares had been replaced by iron wares. Bronze was mainly made of small ritual vessels and handicrafts for the enjoyment and appreciation of princes and nobles. Therefore, its craftsmanship developed in the direction of exquisiteness, beauty, magnificence, and artistry. Many of them are decorated with gilt, inlaid gold or gemstones.However, since the Eastern Zhou Dynasty, my country began to circulate metal currency. Due to the large production volume of currency, the style must be standardized and unified, so it must be minted.However, if it is cast with pig iron, it will be brittle, brittle, easy to rust, and the price is low, so bronze is the most suitable material.Therefore, from the Spring and Autumn Period and the Warring States Period to the middle of the Ming Dynasty, the currency was basically cast in bronze, and the copper consumption was considerable.