The word "brass" was first seen in the "Shen Yi Jing· Zhong Ye Jing" written by the Western Han Dynasty. "There is a palace in the northwest, a wall of brass, and a palace of the Emperor." This "brass" refers to What kind of copper alloy is to be tested. "New Tang Book · Food and Food" has the title of "bronze" and "brass", which refer to the color of ore and smelting products respectively, not the current copper-tin alloy and copper-zinc alloy. Song Renhong consulted "Da Ye Fu" There is also "there is brass, the pit has a name, the mountain is more and more simple", referring to the pure copper refined by the fire method. The term brass refers to the copper-zinc alloy, which began in the Ming Dynasty and its record is found in "Ming Hui Dian": "Jiajingzhong is an example, Tongbao money six million texts, combined with two fire brass forty-seven thousand two hundred and seventy-two pounds.... ”
Through the analysis of the composition of the copper coins of the Ming Dynasty, it is found that the true meaning of brass in the Ming Dynasty is more late than other copper alloys. This is because the acquisition of metallic zinc in brass is difficult. . Zinc oxide can be reduced to metal zinc relatively quickly at a high temperature of 950 ° C to 1000 ° C, and liquid zinc has already boiled at 906 ° C, so the metal zinc obtained by reduction is present in a vapor form. The reaction is reversed upon cooling, and the vapor zinc is reoxidized into zinc oxide in the furnace, so that a special condensing device is required to obtain the metal zinc. This is why the use of metallic zinc is much later than the use of copper, lead, tin, and iron, and is one of the reasons for the late appearance of brass coins. However, brass pieces and brass pipes containing more than 20% zinc were unearthed in the Yangzhai Cultural Relics Site of Jiangzhai. Two kinds of brass cones were also unearthed in the stratum of the Longshan culture in Sanlihe, Jiao County, Shandong Province.
Obviously, the appearance of these brass objects does not mean that people mastered the smelting technology of brass before the prehistoric times, but they were inadvertently obtained when they used copper-zinc symbiotic ore. The zinc content of bronzes in the Shang and Zhou dynasties is very low, generally in the order of 10-z. In the Western Han Dynasty and Xinyi, there are individual copper and zinc coins in the money, and some of them have a zinc content of 7%, but this does not mean that the brass coins are produced in the West Han Dynasty. Because these copper-zinc alloys are extremely rare, their zinc content is generally much smaller than the true zinc content of brass by 15% to 40%. Therefore, we believe that these zinc-containing copper coins were produced when the Han Dynasty used copper-zinc symbiotic ore in “Yishan Casting Money”. According to a survey of the relevant mines, Shandong Changyi, Yantai, Linyi and Hubei have abundant copper-zinc symbiotic mines, which makes the smelted copper contain a small amount of zinc. In the Tang Dynasty, due to the standardization of the money-making materials, the content of zinc in the coins that were cast was constant.