Gottfried SemperpolychromyJacques Ignace HittorffFranz Theodor KuglerBritish MuseumVermilionUltramarineStraw yellowYellowRedPurpleBlueAthens, Erechtheion (406 BCE), guilloche molding of an exterior columnar capital with inlays of polychrome glass beads

Michael Faraday

In 1851, the German architect Gottfried Semper (1803-1879), then in exile in London following his involvement in the political events that had shaken Dresden two years earlier, published The Four Elements of Architecture, a text in which he expounded his anthropological theory of the four material and technical foundations of architecture: around the hearth (ceramics and metallurgy) are organised the earth (masonry), the roof (carpentry and joinery) and the enclosure (textiles). This search for the foundations of human construction is part of a demonstration that runs through all of Semper's publications: the existence of polychromy in ancient buildings, in Greece and Rome, but more generally throughout the ancient world. Following in the footsteps of his compatriot Ignace Hittorff, a Cologne-born architect who had settled in Paris, Semper was converted to the polychrome thesis during his first visits to Paris in the 1820s and became one of the staunchest defenders of the vision of a multicoloured antiquity, as well as one of the most merciless critics of the 'whitewashed' representation of Greco-Roman architecture and sculpture, notably in an essay published in 1834. Seventeen years later, in 1851, in Die vier Elemente der Architektur (The Four Elements of Architecture), he picked up where he had left off, launching a scathing attack on the art historians who were skeptical of these theses, in particular Franz Kugler, who had questioned the idea of the omnipresence of polychromy, arguing, for example, that it was inconceivable that the most precious marbles should have been covered in paint. Semper replied that, on the contrary, they were the best supports for ensuring that the colours held and were preserved, and that he had seen for himself that these marbles were not polished but grained. But whereas he had previously based his arguments on textual sources (philology) and field observations (archaeology), including those he had made himself during his stays in Italy and Greece between 1830 and 1833, and on anthropological considerations relating to human constructions, in 1851 Semper added a new piece of evidence that he entitled ‘Chemical Proof’. He published the results of an international commission that had met at the British Museum on 1 June 1837, in the presence of Hittorff and several British specialists. All agreed that there were vestiges of polychromy on stones from the Erechtheion as well as on marbles from the Parthenon and the Temple of Aegina. Underground excavations, in particular, revealed fragments of marble coloured a very bright vermilion, an ultramarine blue based on copper, or a straw yellow, with very marked contrasts. Yellow, red, purple and blue glass beads were also found between the volutes of the Ionic columns in the four-columned portico of the Erechtheion. The chemist Michael Faraday, who had submitted a report on 21 April 1837 that was cited at the British Museum meeting, attested not only to the existence of chemical traces of colouring but also to the presence of fragrant waxes and resins (‘a fragrant gum’). For Semper, this ‘chemical proof’ brought the debate to a close and had the flavour of a triumph.