Coins authenticity

The data represented by the open squares in Figure 5 were obtained from streaks of modern fake Sasanian coins (4). Note that the gold levels for these fake coins are usually appreciably less than those for authentic coins. This is because silver used in the last 100 years almost always... 

Sandu, I., F. Diaconescu, I. G. Sandu, A. Alexandru, A. Sandu, and V. Andrei (2006), The authentication of old bronze coins and the structure of the archaeological patina, Analele Universitatii "Dunarea de Jos" din Galati, Fascicula IX Metalurgie si Stiinta Materialelor, 24(1), 38-48. 

Coins were valuable as money, but they were also artistic endeavors. Metals have been used in numerous ways in art objects. The great value of certain art objects has increased the need for authentication, which is a... 

One of the earliest known references to coal was made by Greek philosopher and scientist Aristotle, who referred to charcoal-like rock found in Thrace (a region on the northeastern shore of the Aegean Sea) and in northeastern Italy. Although authentic records are unavailable, historians believe coal was first used commercially in China. Reports indicate the Fu-shun mine in northeastern China provided coal for smelting copper and for casting coins around 1000 BC. 

The name quinacridone first coined by Niementowski [1] in 1896 and attributed to the compound 1 was obtained by reaction of phloroglucinol with anthranihc acid. Although a linear isomer of 1 was assumed to have formed also, it was demonstrated [2] subsequently that the presumed mixture consisted entirely of the angular isomer 1. In 1906, it was erroneously claimed [3] that Unear quinacridone 2 in the form of yeUow crystals resulted from cycUzation of l,4-bis(o-carboxyanilino) benzene 3 in concentrated sulfuric acid. Years later, the product was demonstrated to be the angular isomer 4 (Scheme 18.1) [4]. The first authentic example of the Unear quinacridone ring system was demonstrated by Sharvin [5] by the synthesis of quinacridonequinone (QAQ) 5. Other claims to the synthesis of Unear trans-quinacridone 2 were either demonstrated or presumed to be erroneous. 

Despite what a number of historians or chemists have maintained, Lavoisier did not introduce the precision scales into chemistry either, as they had been used by alchemists, apothecaries and assayers for centuries. They were essential to a number of qualitative tests for purity, and were indispensable for determining the specific weight of metals, a key to ensuring the authenticity of coins or establishing the nature of alloys and amalgams of all sorts. 

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