Chapter 7 Section 4 Two Unique Types of Cupronickel in Ancient China

In ancient China, two brilliant silver-white copper alloys were invented and developed. One is arsenic-nickel copper alloy, which is made by arsenic spotting; the other is nickel-nickel copper alloy, which is made by refining copper ore and nickel-containing ore. . The origin of arsenic cupronickel is very early, and it is completely the result of Chinese alchemy activities.In the Jin Dynasty, some alchemists used realgar (ASS) to turn red copper into arsenic brass. It was a copper-arsenic alloy containing about 5% arsenic, and it was called "xiongjin" at that time.Su Yuanming, an alchemist in the Sui Dynasty, was very experienced in this. He heated realgar and plant ash (rich in KCO) together to make the so-called "volt fire realgar" (that is, potassium arsenate), and then used this "point medicine" Refined together with red copper and charcoal, male gold is obtained.In the late Tang Dynasty, Jinlingzi, the alchemist mentioned above, developed this technique. He first mixed the highly poisonous arsenic (ASO) with flour and water, kneaded it into a ball, stuck it on a willow stick, dried it in the shade, and then Melt the red copper, insert the wooden stick with arsenic clumps directly into the lower layer of liquid copper, and keep stirring, the arsenic in ASO is quickly reduced to elemental arsenic by the carbonized flour, and immediately dissolves in the copper.After many repetitions, when the arsenic content in copper exceeds 10%, a silver-white copper-arsenic alloy is formed, that is, "copper turns into silver", which he called "Danyang silver".This is how Jinlingzi completed a very dangerous chemical experiment in a very clever way.This kind of white copper is very hard, white as silver, very beautiful.But it is toxic, and after a long time, the arsenic in it will slowly volatilize and gradually turn yellow, and the color cannot last, so it has not been developed into a practical alloy.However, it should be said that it is a remarkable chemical achievement to be able to tap this kind of alloy which is very difficult to refine in ancient times.

Nickel-nickel-nickel copper has been a special product in Yunnan and Sichuan since ancient times.There is a so-called "鋈" [wu mistake] in ancient Chinese books, which may be this kind of white copper.In the Eastern Jin Dynasty, Chang Chu wrote a book "Huayang Guozhi", in which he said that "Tanglang County produced silver, lead, white copper, and miscellaneous medicines because of the name of the mountain."According to Tanglang County, which is now Huize and Qiaojia in Yunnan, the cupronickel produced there can be sure to be nickel cupronickel.This shows that nickel-nickel-nickel copper was smelted in the Jin Dynasty and trafficked to the Central Plains.According to the "Book of Tang", at that time only the bullock carts of the first-rank officials were allowed to use cupronickel decorations.In the Qing Dynasty, the production of cupronickel in Yunnan reached its peak, and cupronickel basins, ink cartridges, incense burners, candlesticks, and hookahs were sold at home and abroad and were extremely popular.The "Yu Heng Zhi of the Dianhai Sea" written in the Jiaqing period once described the grand occasion of the production of white copper in Yunnan at that time, "there are many people living in four places, there are many kinds of utensils, and craftsmen come from far away".In the Qing Dynasty, there were still many works describing the mining and taxation of white copper in Yunnan, but none of them clearly stated the minerals and smelting methods used to refine white copper.

In 1946, Yu Xiyou, a modern mineral geologist, conducted a field investigation on the production of nickel-nickel-nickel copper and wrote a book called "Minerals of Xikang", which clarified the details of Yunnan's traditional nickel-nickel copper craft for the first time.In recent years, some people have further investigated the traditional copper-nickel craft in Huili County, Sichuan (at the junction of Sichuan and Yunnan). They learned that the raw material for refining nickel-iron ore (nickel-iron sulfide, Limahe, Qingkuang, Huili County, Sichuan) There are ancient nickel ore sites everywhere, and ancient ore samples can be collected) and chalcopyrite or tetrachtrite (CuO). Matte nickel" (the main components are NiS, CuS and FeS), and then put it into a copper furnace for repeated roasting to remove the sulfur.It is then returned to the copper smelting furnace to reduce it to a crude nickel-copper alloy with charcoal.Finally, refined copper is smelted with this crude alloy at 1300-1400°C to obtain white copper.However, the so-called Yunnan white copper is usually deliberately mixed with brass or Japanese lead, so it is a Cu-Ni-Zn ternary alloy, containing 40-58% copper, 7-32% nickel, and 25-45% zinc. %, it is said that it can make white copper "bright and tough".

In the 18th century, white copper from Yunnan, China was trafficked to Europe by the East India Company. It was very popular and very expensive, second only to gold and silver, so it was only used as decoration for nobles' private residences.It was not until 1832 that the British Thomason (E.Thomason) imitated this alloy.In the following year, the two Henninger brothers in Germany also succeeded in imitating it and named it "German Silver". Some historians of science did not understand that there were two kinds of cupronickel in ancient China, so they interpreted "nickel cupronickel" as nickel cupronickel, and many mistakes occurred, so when reading, pay attention to distinguishing, all cupronickel indicated by arsenic stone is arsenic cupronickel.