Hallmark — a History of the London Assay Office

solders, ie yellow-gold colour, melting temperature below 800°C, 4 Extraction and Metallurgy strong adhesion, corrosion resistance, fluidity, wettability at a level Amongst the gold papers presented in this section were: of properties of the Au/Ag/Cd/Cu 750 - 30 gold solder. The Xi’an ‘Optimization of Gold Grade in Production Using Regression and workers have developed new gold- and silver-palladium alloys Genetic Algorithm’ by Q.X. Yun, Z.Q. Wang, C.W. Lu and X.Z. which meet the Chinese requirements of biocompatibility, Lan of Xi’an University of Architecture and Technology, describing mechanical properties, chemical properties and cast accuracy. a new approach which has been used in Jinshan gold mine in China; and ‘Mathematical Models of Lime-Roasting Pretreatment 2 Alloys and Materials of Refractory Gold Ore’ by Zhang Pengfei and Chen Jin from A plenary lecture entitled ‘Progress of Research and Applications of Changsha Railway University and Central South University of Precious Metals Micro Irregularly Shaped Composites’ was given Technology, Changsa describing approaches relevant to the gold by Li Mingli, Bai Wenchao, Li Yin’ee and Wang Jinming of the ore located in Hunan. Northwest Institute for Non-Ferrous Metals Research, Xi’an, China. Switching contacts and spring push buttons in All the papers and posters presented at the Symposium are communications technology, keyboard contacts in computers and published in a comprehensive hard-backed conference proceedings electronic devices, and plug connectors in electronic systems book* edited by Professors Deng Deguo, Lan Xinzhe, Yang Yikun require the contact function to be absolutely reliable during long- and Li Guanfang. Much of the work described from laboratories in term use. As they have an excellent stability, gold and high gold China was of an ‘upstream’ nature (3), being basic research with an content alloys of other precious metals cannot be replaced by any industrial orientation, and it was encouraging to see so many other precious metal. young people making the presentations. David Thompson 3 Refining and Recovery There were a number of papers in this section on various aspects of gold refining. The titles were as follows: ‘Solvent Extraction of REFERENCES Gold(I) in a Mixed Alcohol-Diluent-Surfactant-Au-(CN)2-- System’ by Hwang Kwn and Chen Jing of the Kunming Institute 1 D. McDonald and L.B. Hunt, ‘A History of Platinum and its Allied Metals’, Europa of Precious Metals; ‘Studies on the Performance of Extracting Publications Ltd for Johnson Matthey, 1982 Au(III) from HCl Medium with Petroleum Sulfoxide’ by Gu 2 D.T. Thompson, Gold Bull., 1998, 31, 111; 1999, 32, 12 Guobang, Yi Xiaoyun and Li Yanli of the Institute of Chemical 3 E. Konecny, C.P. Quinn, K. Sachs and D.T. Thompson, ‘Universities and Industrial Engineering, South China University of Technology, Guangzhou; Research’, The Royal Society of Chemistry, Cambridge, UK, 1995 and ‘Adsorbing Gold with Activated Carbon Fibre from Cyanide * The book of Proceedings can be obtained (60 US$, including postage) from and Chloride Solutions’ by Lu Yuehua and Shui Chenjing of the Ms Li Ming, Kunming Institute of Precious Metals, Kunming 650221, Yunnan, China; Kunming Institute of Precious Metals. Fax: +86 871 515133). BOOK REVIEW Hallmark – A History of authority sought to provide an assurance and 2 pennyweights (equivalent to a 925 the London Assay Office of their value. The Romans occasionally millesimal purity). This quality had to be marked ingots of gold and silver with demonstrated by an assay undertaken by By J S Forbes, Unicorn Press, official stamps guaranteeing purity and, “the guardians of the craft,” who would London, 1999, pp. 367. from the late fifth century AD, similar stamp the silver article with a leopard’s ISBN 0 906290 260 Price £35 marks were applied to wrought metal. The head as a mark of conformance. In 1327, practice of hallmarking silverware was the goldsmith’s guild was granted its first Hallmarks serve as a guarantee of precious introduced in France in 1275 and it spread charter by Edward III but it was in 1478 metal content and represent an early form to much of western Europe by the early that the Assay Office was consolidated as of consumer protection. The idea fourteenth century. a permanent institution with the originated with the invention of coinage by The foundations of the hallmarking appointment of Christopher Elyot as the the Lydians of Asia Minor sometime in the system in England were laid by the passing first full-time, salaried assayer. seventh century BC. By stamping fixed of a statute of Edward I in 1300, which Remarkably, the Assay Office has weights, or coins, of precious metal with decreed that all silver articles had to be up occupied the same site within the their distinctive mark, the minting to the sterling standard of 11 troy ounces Goldsmith’s Hall complex close to 136 Gold Bulletin 1999, 32(4) rescued from the fire of London in 1666 was a spin-off from the development of by a quick-thinking goldsmith and city silver and gold extraction and refinement alderman, who commandeered a cart to sometime after 3000 BC(1). A sample of carry away the Goldsmith’s Company’s the item is taken as a scraping. This is plate and records to safety. Forbes also weighed, wrapped in lead foil and placed garnered material from other collections, in a crucible (or cupel) of bone ash. It is including those of the Public Records then heated in a muffle furnace, which Office and the British Museum. results in the base metals being oxidized Considerable attention is paid to the and absorbed into the crucible. The personalities associated with the London residual pellet is reweighed, to determine Assay Office. For example, the author precious metal purity. For gold alloys, a charts the running battles of Thomas further stage is necessary in which the Keeling, assayer for almost two decades in silver is removed chemically from the the sixteenth century, with Richard pellet. This operation, traditionally known Martin, a powerful city figure and Warden as “parting,” was formerly accomplished of the Mint. This episode and several using a mixture of brick dust, salt and others related in this book illustrate the “misy” (sulfates of iron and copper). A repeated hostility attracted to the assayers strikingly similar recipe for purifying gold over rejected wares, which had to be is described in the oldest surviving broken up, or purported damage to metallurgical text, the Leiden Papyrus X, articles by sampling. In the early years, dating from the early fourth century serious offenders against the hallmarking AD(2). Forbes points out that modern Figure 1 Silver-gilt tazza bearing the regulations were “named and shamed” by assays of a series of surviving silver and hallmark for 1584, while being put in the stocks in the Goldsmith’s gold standards dating back to 1560, which Thomas Keeling was assayer, Hall, in full view of guild members. were prepared by the Assay Office for the published with permission from The Worshipful Company of However, the life of the assayer could not Royal Mint, are remarkably accurate Goldsmiths. have been too stressful, because since considering the crude tools, furnaces and 1478, there have only been 41 head weighing balances that were then London’s Guildhall for over six and a half assayers, making the average period of available. This is despite the fact that a centuries without a break. Also in 1478, the office more than twelve years. Forbes leads scientific understanding of the process of date letter was added to the mark of the the reader through the annals of the Assay cupellation was only gained in the later manufacturer, following the French Office and conveys its vicissitudes with the eighteenth century, which only goes to example, and together with the maker’s immediacy of contemporary events. The show that it is possible to reliably operate a mark and the leopard’s head it completed incessant pleas of assay staff to their sophisticated technology without knowing the set of the London hallmarks that was to employers for an increase in salary strike a how it works! be maintained over the centuries. By particularly modern chord! For collectors Forbes augments his narrative with a contrast, the compulsory hallmarking of of antique silverware, this book is wealth of well-chosen illustrations, some gold articles had to wait until the enactment indispensable and they will instantly in colour, see for example Figure 1, and of the Plate (Offences) Act of 1738. recognise the names of famous gold- and framed vignettes on selected topics. There John Forbes, a retired Deputy Warden silversmiths which cross its pages. The are also a useful series of appendices and of the Goldsmith’s Company, spent seven author describes the introduction of the end-notes. Typographical errors are few, years of research tracing the history of the different standards, including the although the notes to Chapter 2 are awry London Assay Office. And what a Britannia Standard for silver, explaining and “Inigo Jones” is referred to in the remarkable story he has succeeded in the circumstances for their adoption. index as “Indigo Jones.” The photograph unfolding. He was greatly assisted in his For this reviewer, one of the more of the silver-gilt cup and cover on page task by the minute-books of the fascinating themes running through this 208 is out of focus. But these are tiny Goldsmith’s Company, which run from book is the endurance of the fire-assay blemishes in what is a well-written and 1334 onwards, apart from the loss of a technique, or cupellation, through the thoroughly stimulating book. single volume covering a period of thirteen ages and it remains the most cost- and David M Jacobson years in the sixteenth century.

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