An 'unholy' alchemy: the nineteenth-century European medico-scientific encounter with opium smoking and the circulation of knowledge.

Today, the story of the opium trade is an almost archetypal representation of the social, economic and military power dynamics at play in the colonial world. But few, if any, are aware that the European encounter with Chinese opium smoking spurred a European interest in opium vapour therapy, or that its spirited uptake in European medicine inspired a research programme that spanned the continent for more than half a century. Opium smoking was intoxicating, something which experimental science suggested should be impossible, since the chemical properties of opium's active alkaloids all but precluded the possibility of vaporization. Recalling opium smoking's entrance into medical practice and the subsequent experimental interest in the chemical constitution of opium vapour, this paper reconstructs the history of European 'opium science'. In doing so, it realizes opium science as the site of competing definitions of the biomedical reality implicated in the experience of opium intoxication, one centred on the intoxicated experiences of the colonial subjects themselves. Far from being a simple story of exchange between centres and peripheries, it examines the polycentricity of knowledge circulation in the colonial world and the implacable agency of intoxication.