Bronze excavated

Bronze disease necessitates immediate action to halt the process and remove the cause. For a long time, stabilization was sought by removal of the cuprous chloride by immersing the object in a solution of sodium sesquicarbonate. This process was, however, extremely time-consuming, frequentiy unsuccesshil, and often the cause of unpleasant discolorations of the patina. Objects affected by bronze disease are mostiy treated by immersion in, or surface appHcation of, 1 H-henzotriazole [95-14-7] C H N, a corrosion inhibitor for copper. A localized treatment is the excavation of cuprous chloride from the affected area until bare metal is obtained, followed by appHcation of moist, freshly precipitated silver oxide which serves to stabilize the chloride by formation of silver chloride. Subsequent storage in very dry conditions is generally recommended to prevent recurrence. 

Bronze disease is the name given to a form of corrosion of bronze and some other copper alloys, in which light blue-green outgrowths form on the surface (see Fig. 41). It is an especially obnoxious form of corrosion that particularly attacks ancient excavated bronze objects. Unless terminated by specialized treatment soon after excavation, bronze disease usually results in the complete corrosion and total destruction of the object. 

The appearance of the first appendices of chemical analysis and references to them in the text of a major excavation report represents the earliest significant collaboration between archaeologists and chemists. Examples include the analysis of four Assyrian bronzes and a sample of glass in Austen Henry... 

The composition of bronze artifact corrosion products excavated from several lacustrine sites could be explained in relation to some characteristics of the environment. In one study, a combination of potential pH diagrams for copper and those defining different types of natural soil was used to explain the composition of corrosion products of copper artifacts excavated from different locations. While sulphides are predominant in anaerobic conditions, mostly carbonates are... 

Among the technologies in existence by ca 4000 bc, which included the manufacture of synthetic lapis lazuli, the development of the first true pottery kilns must rate as a significant achievement (1). For polychrome pottery to be successfully manufactured, it was essential to separate the fire (fuel) from the work (clay pottery). The excavations performed in the near east (Mesopotamia in antiquity) indicate that these early kilns were probably of beehive construction. Subsequent Egyptian pottery kilns of the period ca 3000 BC were the familiar chimney shape. With the smelting of copper in pit hearths predating by perhaps a millenium millennium the start of the Bronze Age at ca 3000 BC, another important advance was the invention of the bellows at ca 2000 BC. Bellows supply combustion air where it is needed and are used as a means of raising furnace temperature. 

Instrumental neutron activation analysis was used to determine concentrations of several major and trace elements in samples of heavily corroded residues found in crucible fragments excavated at Tel Dan, Israel. The residues were mostly hard, metallic phases admixed with nonmetallic inclusions that appeared to be ceramic material from the loose porous interior of the crucible itself The objective was to identify the metals that had been melted in these crucibles. A method is described that attempts to separate nonmetallic and metallic phase data. In comparison to previous reports on analyses of source materials thought to have been used at Dan in this period (Late Bronze II Age-Early Iron I Age 1400-1000 B.C.), high gold concentrations were found. These appear to be correlated to arsenic and antimony concentrations. This finding is discussed in relation to possible changes in the source of tin at this period. 

Samples 801, 802, 803, 804, 805, and 1015 are from area B-l (dated to Late Bronze Age I/Late Bronze Ha Age transition period) that was excavated in the 1985 season. 

The original interest in these excavated samples stemmed from the important role of bronze and the historical implications of the extensive tin trade routes in the Middle Bronze Age (2200-1600 B.C.). As bronze metallurgy developed from the earlier use of copper and arsenical copper, tin sources became vital (14). By the Middle Bronze Age, the limited distribution of tin deposits throughout the world and the ample supply of copper were well-known, and extensive tin trade routes had been established to supply the metallurgical centers of the world with this then-considered precious metal (15-16). The Ugaritic tablets from Ras Shamra, however, indicate a severe drop in the value of tin around the Late Bronze Age (1400-1200 B.C.). It has been postulated (17) that this drop was related to the discovery of more accessible sources of tin. 

The bronze production in China was both long-lasting and extensive. A lot of bronzes were produced in these 3000 years As an example, over 1295 mirrors have been excavated and listed in publications during 1923-1966 when Barnard compiled his tables (4). When we add the pieces in Western collections which have come out of China without provenance data and the numbers of objects lost, still undiscovered, or melted down as scrap, the totals are staggering. The story of Chinese bronze alloy compositions is a complex one. 

Barnard looks closely at the lead compositions of bronzes and concludes that Shang bronze is for the most part a binary alloy (4). In Western Chou bronze was a ternary alloy with 2-7% lead, and in Eastern Chou the Chinese bronzes have higher lead. This, indeed, seems to go along with what we found. Barnard stresses, correctly, the problem of working with unprovenanced material—objects which have not come from archaeological excavations and which have no reliable data about their sources. In any case, the picture of ancient Chinese bronze alloying seems to be complicated and confused. No clear conclusions have been drawn, and no firm picture emerges. 

All of the above charts were made from analyses of Chinese bronzes which are unprovenanced or at least not archaeologically excavated. To see how they compare with excavated material we have included Figures 16 and 17, which show analyses of excavated material as published in the... 

Figure 16, Excavated bronzes, chronologically data normalized by...

Figure 17. Excavated bronzes by type data normalized by weight to ...

Olives appeared in Israel about 45,000 years ago (1). Charred pieces of olive wood have been found in excavations at Lower Boker-Har Hanegev in layers dating to 42,980 B.c. Both charred wood and carbonized stones have been found in many archeological sites in Israel dating from 8000 b.c. onward, and indirect evidence suggests the use of wild olives O. oleaster) by humans as early as the seventh millennium b.c. (3). It is not known whether the carbonized stones and charred wood obtained from Chalcolithic (fourth millennium b.c.) and Early Bronze Age (2900-2700 B.c.) sites represented cultivated or wild olives. 

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