Early Metallurgy

On 11 October 2003 the Society for the History of Alchemy and Chemistry held a joint meeting with the Society for the History of Medieval Technology and Science (SHMTS) in the Conference Room of the Science Museum Library on the subject of Early Metallurgy. This was the first joint meeting to be held between the two societies and resulted from a suggestion made by Dr Frank Greenaway. Twenty-six people attended the meeting, which covered a range of metallurgical topics, and an enjoyable lunch was arranged by SHMTS at the Polish Club on Exhibition Road.

The first paper was given by Dr Paul Craddock of the Department of Scientific Research at the British Museum, with the title "Metal Distillation in the Medieval Period, an Early Application of Science to Industry". The talk described the development of zinc distillation technology, in India about 1000 years ago, and quite independently in China around 500 years later. Dr Craddock explained how both technologies could be viewed as the adaptation of scientific techniques to make pragmatic industrial processes.

Following on from this, the distillation technologies also could be seen as more typical of the sort of processes associated with the European Industrial Revolution of the eighteenth and nineteenth centuries. The paper showed that perhaps the study of early technology has been too centred on the Romano-Greek tradition and on Europe and the Mediterranean, and also that the development of sophisticated industrial technologies of mass production was a much longer and broader based phenomenon than is sometimes credited.

The Indian zinc distillation process ceased around 200 years ago, but the medieval furnaces, still bearing their last load of retorts, survive just beneath the surface at Zawar in Rajasthan. The traditional zinc distillation process is still practised in some remote areas of western China, which Dr Craddock demonstrated by showing a video of his visit there. Dr Craddock concluded by highlighting how the excavation and scientific study of the physical remains of processes and the recording of surviving technologies can be invaluable in recreating past technologies and in the interpretation of the often rather enigmatic contemporary literary sources on early science and technology.

Dr Barrie Cook, Curator of Late Medieval, early Modern and Modern Coins (to 1800) at the British Museum, gave the second paper, which was entitled "Crimes Against the Currency in Twelfth and Thirteenth Century England". The paper identified and discussed a significant change in the attitude to crimes against the currency in medieval England.

In the Anglo-Saxon and Norman periods the frequent change of design of the silver penny, and associated recoinage, were features of the English monetary system. This policy had the effect of maintaining the currency to a good standard by minimising the impact of potentially damaging intrusive elements, such as clipped coin, counterfeit coin and foreign coin. As a result, the main concern on the part of the royal government was to prevent fraud inside the system, on the part of the moneyers who were responsible for making and distributing the coinage.

In the mid twelfth century the English money system was changed, and recoinages became far less frequent, no more than one a generation or less, and new coin joined much older accumulated coin of the same design. There was thus a much larger potential for the currency to become poorer in standard. The result, from the twelfth century onwards, was a greater need to actively police the currency in use. Along with this went a much more aggressive attitude to clippers and counterfeiters, and an increase in severity in the punishment of these crimes, now aligned in the mind of government with treason and felony. Dr Cook concluded by giving evidence for this shift from government ordinances, legal cases, and chronicle reports illustrating the different ways in which offenders were punished.

After lunch, Dr Alan Williams of the University of Reading presented a paper entitled "The Creation of the Suit of Armour in Fourteenth Century Italy". He began by explaining how all cultures developed protective garments for warriors. These were usually flexible armours made of numerous small pieces of metal loosely joined together. Europe was unique in devising rigid defences of large plates shaped to fit the wearer and articulated like an exoskeleton. However, these suits of armour were very expensive to produce.

While the suit of plate armour offered an extremely effective defence against missile weapons, it placed unusual demands upon the metallurgical industries of medieval Europe. These demands were met for the first time in fourteenth century Lombardy, and enabled an enormous export trade to develop. Dr Williams then explained the technical aspects of armour production and the use of quench hardening. The later mass-production of cheap suits of armour was then to be accompanied by radically different forms of iron-making in the early modern period. Dr Williams concluded by discussing examples of sixteenth century armour. The metallurgical processes used were adapted to incorporate the demand for highly decorative armour, which although including finishes such as gilding, did not affect the functionality of the armour.

The final paper was given by Tru Helms and entitled "Document Based Speculations on Italian Bronze Casting Technology". She explained that whilst much work has been done on the casting technology of small bronzes using analytical techniques, such methods are not as successful when applied to large bronzes and so she outlined her approach to the subject. The commissioning and/or payment records for seventy-five fifteenth and sixteenth century Italian bronze sculpture projects, when studied in conjunction with sixteenth century treatises by Gauricus, Biringuccio, Vasari and Cellini, provide invaluable information on workshop procedure, technology and transmission of technical information.

By comparing the materials purchased, any notations that characterize them, and the timing of their purchase within the timeframe of the project with descriptions in the treatises of direct and indirect casting methods it is possible to speculate about the technology being used. The essential materials needed for direct casting are clay, cloth clippings, wax, ironwork, fuel, and metal, while gesso is the only material that has to be added to that list for the most straightforward of indirect casting methods.

The materials ordered for Francesco di Giorgio's Angels for the Cathedral of Siena, 1488-1490, are with one exception identical to the materials needed for an unusual method of indirect casting described by his fellow Sienese, Biringuccio. A model, made of tow and paste clothed in wax impregnated cloth, is burned out of the mould, then a layer of wax is applied to the negative and a clay core packed in. The major difference was that the Angels had cores of gesso, not clay. This is one example of the way that the materials specified in documents can be used to suggest the particular technology, or variation, a sculptor was using as well as the possible transmission of technology and Ms Helms gave various other examples in her paper.

Anna Simmons