Classification of Pure Chemical Substances before

It is therefore obvious that the chemistry of pure substances can be defined only on the basis of its objects of inquiry. But it should be noted that in the eighteenth century it were the chemists themselves who distinguished these objects of inquiry from other ones in their practices of classification. We argue that their distinction corresponds exactly with the boundaries of objects of inquiry in the tableau of the Meth-ode. The question raised above was whether the authors of the Methode were the first to see an inner bond among the many different activities with pure chemical substances scattered through all domains of chemistry, or whether their distinction of the particular sphere of the chemistry of pure substances followed a tradition established earlier. Fortunately, there exists unmistakable evidence for such a tradition. The famous tables of chemical affinities testify unambiguously to the existence of this particular chemical practice. The first of these tables was the Table des differents rapports constmctedby Etienne Francois Geoffroy (1672-1731), published in 1718. We can thus even determine when the distinction of operations with pure chemical substances first became manifest, namely approximately seventy years before the Tableau of 1787. 

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