Rob Laffecteur was neither. Technically, a rob (pronounced rōb, as in “robe”) was a thick, sweetened fruit or vegetable concentrate. Rob Laffecteur was merely a syrupy liquid, the flavor of which existed only to camouflage its secret active ingredient. The appellation “Laffecteur” was also a subterfuge: The actual inventor was a Parisian physician, Pierre Boyveau, who was himself clandestinely funded by his father-in-law, the Marquis de Marcilly. In prerevolutionary France, aristocrats had no objection to money, per se, as long as they were not detected participating in anything as déclassé as commerce. To avoid sullying their reputations, Boyveau and the Marquis hired a minor official in the Ministry of War, Denis Laffecteur, to act as a front man for their enterprise. Boyveau was equally reticent about his concoction’s composition. Though it was an article of faith at this time that no syphilitic treatment could succeed without mercury, when Laffecteur applied for a royal warrant in 1777 he insisted that his rob contained none of this essential ingredient. Critics first challenged the rob’s efficacy, but they were silenced by a successful demonstration at the Bicêtre asylum in Paris. Detractors then insisted that if it was effective it had to contain mercury, but numerous attempts failed to discover any trace. In 1778, rob Laffecteur was granted its royal warrant.
Bernhardt M. The Rob. JAMA Dermatol. 2014;150(4):357. doi:10.1001/jamadermatol.2013.9906