Coins compositions

Arsenic occurred in rather high concentrations (0.2% to about 0.4% see Figure 6) in the coins struck before about 135 B.C. From about 160 to 135 B.C. (an approximate date that marks a rather important change in coin compositions in general), the arsenic contents of four coins are greater than 0.8% (assuming that coins A-275 and A-271, which have the prow of ships as found on other Roman Republican asses but which cannot be specifically identified, are dated within this period). Probably arsenic was deliberately added to these four coins (or perhaps an ore exceptionally rich in arsenic may have been used). Almost all of the coins made after 135 B.C. contain relatively low concentrations of arsenic. 

Chemical compositions of Republican copper-based coins are markedly different from those of Imperial coins. In the time of Augustus, the coin compositions changed considerably from those of earlier Republican coins. The coins of Augustus that were minted in Rome were much purer they were struck in two materials in essentially pure copper and in brass (15). 

Perhaps the most extensive appHcation for conversion-rolled, explosion-bonded clads was for U.S. coinage in the 1960s (34) when over 15,900 metric tons of explosion-clad strip that was suppHed to the U.S. Mint helped alleviate the national silver coin shortage. The triclad composites consist of 70—30 cupronickel/Cu/70—30 cupronickel. 

Ringer s Lactate. In 1883, it was discovered that the excised ventricle of the frog would beat for some hours if suppHed with an aqueous solution of sodium, potassium, and calcium salts. The concentration of potassium and calcium was found to be critical, whereas the amounts of the anions had htde effect on the frog heart. The composition of this saline, coined Ringer s solution, is given in Table 1. Many years later it was shown to be very close to that of frog plasma. 

Figure 6. Lithium cycling efficiency of composite lithium anodes in an Li/a -V205 coin-type cell (thickness 2 mm, diameter 23 mm) with 1.5 mol L 1 LiAsF6 - EC/2MeTHF. ...

A specific feature of the CEMS technique is the possibility for nondestructive testing of the surface composition of paintings, ancient coins, and pottery or other valuable objects. Wagner et al. [445] have investigated Celtic gold coins (from the time period 480-15 b.c.) and have shown that the surface of the coins consist of two phases, one of which is strongly eiuiched in gold compared to the bulk composition. 

Composition usually reflects the level of development of the metallurgical technology and the economic trends at the time when, and at the place where the coins were struck. 

Compositional variations in sequential coin issues, say, from year to year, may reflect differences in the source of the ores from which the coinage metals or alloys were extracted. 

Compositional variations within a single coin issue point to variations in the quality control of the metallurgical processes. 

Compositional differences of particular coins make it possible to recognize imitations and fakes. 

Over the past two decades, the pharmaceutical community has become acutely aware that many substances of interest can be obtained in more than one crystal form, and that the properties of these solids may often be quite different. Polymorphism is the term used to denote crystal systems where a substance can exist in different crystal packing arrangements, but all of which are characterized by exactly the same elemental composition. Other crystal variations are known where a given substance exists in different crystal packing arrangements, but each of which exhibits a different elemental composition. Since this latter phenomenon usually involves the inclusion of one or more solvent molecules in the crystal, the term solvatomorphism has been coined to replace the inconsistent nomenclature used over the years. These and related phenomena have been the focus of several recent monographs [1-3],... 

In-situ x-ray diffraction (XRD) was performed on a coin type cell with a 4x6 mm Kapton window coated with conductive thin copper layer. The graphite electrode was pressed against the Kapton window so as to be reached by the x-ray beam. After several lithiation/delithiation cycles under a C/10 rate between 1.5 and 0V, the cell was fully delithiated up to 1.5V. The cycle capacity achieved with the graphite electrode is about 360mAh/g. The cell was then re-lithiated under a slower rate of C/20. XRD patterns were taken for about five minutes every hour while the cell is under continuous discharge. As result the lithium composition x in LixC6 was incremented by 0.05 between two successive XRD scans. 

As mentioned above, the name haptoglobin was coined to designate plasma components forming stable Hb complexes in which the Hb has acquired the properties of peroxidase. To describe an unidentified substance simply by the properties of its complexes with only one other substance is unsatisfactory. Hp as well as Hb from different species will presumably vary to some extent in composition, in the stability of their complexes, and in their peroxidase properties. Thus dog Hp, for example, links human or dog Hb, but the latter Hb complex shows only weak peroxidase activity in Jayle s conventional peroxidase test (N5). 

Mitchiner, M.B., Mortimer, C. and Pollard, A.M. (1985). The chemical compositions of English seventeenth-century base metal coins and tokens. British Numismatic Journal 55 144-163. 

Perhaps the simplest archaeological question that can be answered by chemical means is what is this object made from . The chemical identity of many archaeological artifacts may be uncertain for a number of reasons. Simply, it may be too small, corroded, or dirty to be identified by eye. Alternatively, it may be made of a material that cannot be identified visually, or by the use of simple tests. An example might be a metal object made of a silvery-colored metal, such as a coin. It may be pure silver (in practice, a silver alloy containing more than about 95% silver), or it could be a silver-rich alloy that still has a silver appearance (silver coins with up to 30% copper can still look silvery, in which case the precise composition may well... 

---