The Mixed Blessings of Pragmatism. Jean-Baptiste Dumas and the (Al)chemical Quest for Metallic Transmutation

There were at least three prerequisites for the transmutability of metals to become once again a scientifically acceptable subject of research from the 1810s: new hypotheses concerning the mutual reducibility of certain elements, such as those of integer multiples and protyle put forward by the British chemist and physician William Prout; the experimental confirmation that chemical compounds with the same percentage composition could be substances with very different properties, i.e. the discovery of isomerism and allotropy; the comparison between metals and compound radicals of organic chemistry. This paper aims at illustrating how these premises were exploited by Jean-Baptiste Dumas, one of the leading French chemists of the 19th century, to reintroduce in the chemical discourse the alchemical topic of transmutation.