The Experimental Dissection of Molecules

The discourse at the Royal Institution on 6 June 1851, Suggestions for the Dynamics of Chemistry derived from the Theory of Etherification, was intended for a broad audience, as was generally the case in this famous lecture series begun twenty-five years earlier by Michael Faraday. Williamson averred that the dynamics of chemistry will commence by the rejection of an unsafe and unjustifiable hypothesis, namely that the atoms are in a state of rest the various phenomena of change, which are now attributed to occult forces, [will] reduce to [the] one fact of atomic motion. A little reflection is sufficient to show that such a motion actually exists, he suggested, citing the fact 

Williamson ascribed the basis of this model to Claude-Louis Berthol-let. Berthollet had denied the existence of elective (absolute) affinity, emphasizing instead the role of chemical mass he had also elucidated the importance of precipitation, efflorescence, and elasticity (gas formation) in removing products from the sphere of chemical 

Williamson, On Etherification (1851), 231. This is the Williamson ether synthesis using sodium (Na) compounds. I have bolded the molecular pieces thought to be shuffling, but Williamson s pivoting card makes the concept much clearer. The pivoting card is mentioned in the Royal Institution talk and was apparently demonstrated to the audience, but was not illustrated in the published version. 

These details, like the image of the lecture placard, are also taken from Williamson s presentation to the Chemical Society on 16 June 1851. The third-person description of the Royal Institution talk that appeared in the journal of the Royal Institution (the only source) includes only an allusion to the separation of the two steps of the mechanism, by using successively two different alcohols, as proving the truth of his supposition. It is not known whether Williamson included all these chemical details in the Royal Institution talk. 

Williamson s lecture placard, with pivoting card. Source Williamson,/ourno/of the Chemical Society 4 (1851) 231. 

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