<aside> 📄 Anderson, R. G. W. 2000. The Archaeology of Chemistry. In Instruments and Experimentation in the History of Chemistry. Dibner Institute Studies in the History of Science and Technology. Eds Frederic L. Holmes et al. Cambridge: MIT Press, The MIT Press. 6–34.
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Inadequate attention has been paid by historians to the material culture of science and to the skills of scientific practices. Comparing the various scientific disciplines, chemistry has done even worse than average. The balance may have been redressed a little in recent years; still, differences remain in levels of interest between, say, astronomy and chemistry. Books and papers have explored telescopes, planetaria, and astrolabes,' but little or nothing has appeared concerning furnaces, burning lenses, and alembics.
The case of alembics suggests why this might be. The alembic, used for distillation, was certainly known to Greek chemists working in Alexandria and was used by Arabs from the rise of Islam.? It was extensively employed in the West until relatively recently and may continue to be used in out-of-the-way pharmacies even today. It furnishes a striking example of continuity and stability in the history of chemical instruments.
Evidence for the history of the alembic can be found in texts, both in manuscript and in printed form. However, it must be treated with caution. Few alembics are known, or rather known about, and most are fragmentary. They are utilitarian and not objects of high status. Glass examples, being fragile and relatively cheap to manufacture, are likely to have been discarded, and metal alembics rarely survive. They contain relatively little information. It is exceedingly difficult—in fact, nearly impossible— to determine who made them and where they were made. They incorporate little or no contemporary chemical theory. If texts and objects are scrutinized, one finds that the texts are often obscure and illustrations are diagrammatic or inexact. For all these reasons, alembics are scarcely studied by science historians at all. Their presence is unacknowledged. In fact, they may exist in some specialized museum collections but, as they reveal little (or seem to), they are largely ignored.
A worthwhile endeavor might be to reassess this situation and to consider what early chemical apparatus does survive alongside literary description. This would be a major research project and, in this chapter, it can be attempted only in a cursory manner. Only apparatus and texts earlier than the arbitrary date of 1750 are considered, and the argument concentrates on distillation apparatus. Distillation is a process used primarily in earlier times for concentrating alcohol from mixtures of water and alcohol. The product was often used, sometimes with other substances, for medicinal purposes, though distinguishing these from social uses of alcoholic beverages can be difficult. Perfumes were also extracted using distilling techniques.
Nearly all treatises on chemistry make reference to distillation. Distillation apparatus includes some of the most distinctively shaped chemical vessels. Caution is necessary when surveying previous work on this subject because, from time to time, apparatus that was never intended for distillation is identified as such, this being true particularly of spouted cupping glasses and breast relievers, which are sometimes called alembics.
Most examples of texts and apparatus considered are from western Europe, though references are made to the Near East. A small fraction of the surviving archaeological evidence is assessed here: At least 70 single items or groups from a single location are to be found in the literature and, of these, approximately one-fourth are considered very briefly. Only a small proportion of the evidence comes from sources that can be dated even approximately. One might think that a clear evolution of styles of apparatus would emerge, though even if this were the case (which it probably is not), too few examples have a secure chronological base on which to make comparisons. Texts are of some help, but they must be treated with caution, as printed sources became available only some time after the development of chemical practices in western Europe, and manuscripts have so far not proved to be very useful.
Before dealing directly with the material evidence, we consider a little of the literature of early chemical apparatus. The first problems were identified by R. J. Forbes in 1948: "We must remark ... that illustrations of apparatus in medieval manuscripts are neither very numerous nor clear ... [ilt is always well to mistrust their [book] illustrations as they usually refer to the time when the printed edition was issued, which may be several centuries later than the original manuscript."s
This accounts for the derivative nature of many illustrations and of the descriptions of them. For example, the double pelican (used for long reflux distillations) appears in similar form in many works. An early description and an illustration appear in Hieronymus Brunschwig's Liber de arte Distallandi de Compostis of 1512, and this may act as a source for later authors. The pelican is a good example of the disparity that in all likelihood exists between the frequency of description in texts and the actual production and usage of certain items of chemical apparatus.
Nearly every sixteenth- and seventeenth-century text includes a description and a (usually poor) woodcut of the vessel that reveals little of the mode of construction (figures 1.1 and 1.2). Yet very few complete or even fragmentary double pelicans survive. Some illustrations are fanciful, such as those published by G. B. della Porta in 1609, wherein it is difficult to believe that the tortoiselike retort was not engraved to show a closer resemblance to the animal than to its actual form. Other anthropomorphic devices in this work include a tower of alembics intended for fractional distillation and constructed in the form of the multiheaded hydra and an alembic and cucurbit resembling a rampant bear.
Written descriptions vary from the deliberately obscure to the intensely practical. A number of chemical texts incorporated the socalled Tabula Smaragdina, where we find the following description:
Ascend with the greatest sagacity from the earth to heaven, and then again descend to the earth, and unite together the powers of things superior and things inferior. Thus you will obtain the glory of the whole world, and obscurity will fly far away from you.
This alchemical precept refers to distillation or sublimation and provides a revealing comparison with the following clear instructions in a seventeenth-century English translation of Geber:
The distance from the fire, the magnitude of the vent holes of the furnace, and the structure of the furnace are important in achieving and maintaining desired temperatures. The apparatus is placed in an earthen pan full of ashes for some distillations, or wrapped in hay or wool and placed into water, for others. If upon ashes, the apparatus rests upon a layer one finger thick, and is covered with ashes almost as high as the neck …
Undoubtedly, detail was deliberately omitted on occasion, a practice that was sometimes even admitted. Thomas Norton's Ordinal of Alchemy was written in verse form circa 1477. In chapter 6, he lists the uses of a furnace of his own design, but he declines to describe it:
An other fornace for this operacion By me was fownde bi ymaginacion; Nobilly servynge for separacion Of dyuydentis, and for altificacion; It will for some thyngis serve desiccacion, It servith full well for preparacion; So for vj thingis it servith well, And yet for all at oons as I can tell. This is a newe thynge which shall not be Sett owte in picture for all men to see.
What historians can see, or at least can seek, is the physical evidence. This might well precede any written evidence—might because some doubt must surround the two earliest groups claimed: bowl-shaped vessels from Mesopotamia and retortlike apparatus from the Indian subcontinent.
The Mesopotamian evidence is found in material excavated from Tepe Gawra on the River Tigris." Fragments of four ceramic bowls were excavated from levels dating to 3500 Bc. The common feature of all is the double rim, or gutter, around the top. Martin Levey postulated that lids would fit around the circumference, though these have not been found. A vapor could condense on the inner surface of the lid and dribble down into the gutter, whence it could be removed in batches. Two of the vessels, now in Baghdad, have holes in the circumference. Levey further speculated that the gutters might have been filled with comminuted plants, the liquid being distilled leaching out products, presumably of pharmaceutical use.
Distinctive vessels, quite probably for distillation, have been found at widely separated sites in India and Pakistan. The first group to be reported had been excavated in 1930 at Sirkap, site of Taxila in the Indus Valley. 12 The city originated on this site circa the second century BC, and it remained in occupation for three centuries. The still itself was found in levels of the time of the Sáka invasions (i.e., 90 BC to AD 25). The complete apparatus was composed of four elements, all made of ceramic material, and the way in which they fit together provides the argument that they form a distillation unit. The parts are a globular pot; a shallow vessel with a spout close to the rim, which fits on the pot; a tapered tube, which fits into the spout; and a globular vessel with an opening to receive the tube. The archaeologist Sir John Marshall speculatively added a further conjectural component: a water bath in which the globular vessel, the receiver, is placed to increase efficiency of condensation. The still head could not be described as an alembic, as it had no internal gutter. Rather, it is a proto-retort. Large numbers of this type of receiver bottle were discovered in the Vale of Peshawar in 1963 and 1964, from levels datable from 150 Bc to AD 350. Some of the receivers had an impressed "tanga" mark that led the excavator to suggest that this was a royal stamp or license and that such marks indicated ownership, or at least a license, for the ownership of the distilled product that they may have contained. This theory must remain highly speculative, however.
The earliest literary references to chemical practices relate to workshops in Hellenistic Alexandria of the third and fourth centuries. They have been carefully studied and published by Robert Halleux. 14 As regards physical evidence for chemical practices, the best known are those texts that include diagrams of distillation processes. These manuscripts are, however, late medieval copies of earlier texts and afford no certainty that the diagrams illustrate ancient apparatus. They may simply have been brought into the text by the medieval scribe. This possible discrepancy must be examined carefully. The diagrams show alembics, some with two or three separate spouts, examples of which do not survive from any physical evidence that remains (none whatsoever having been reported from Alexandria).15