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Classification of substances in affinity tables

Up to this point, the affinity tables of the eighteenth century attracted the attention of historians of science mainly because of the conception of chemical affinity embodied in them. They were rarely studied as documents giving testimony of cheuucal classification in this period. Among the many merits of Alistair Duncan s profound book on these tables is that it dedicates a section of its fourth chapter to the question of the classification of chenucal substances in this age—see Duncan [1996] pp. 159-168. In the following we further extend and elaborate Duncan s approach. [Pg.155]

From this case, an important general conclusion can be immediately drawn with respect to the table s classificatory implications since the introduction of columns depended partly on the differences in replacement patterns among the single members of a class of substances, one must not necessarily take all columns as classificatory units. This holds a fortiori for later affinity tables where the columns are crowded with substances, the grouping together of which makes no classificatory sense. [Pg.156]

However, it remains an open question whether or not this generic acid also comprises the spirit of vinegar. [Pg.156]

Accordingly, in columns two and three the alkalis and the earth are thought to precede the hsted rows of metals. In column four the alkalis and the earth are hsted anew because, in the case of the sulfuric acid, the Soufre Principe is thought to precede ah sahfiable bases. [Pg.156]

Since not ah of the eleven metals that occur in Geofifroy s table are listed in columns two through four, it remains an open question whether Geoffroy was claiming that ah metals form salts with acids. Geoffroy hsted no salt formed by zinc or Pierre Calaminaire with any of the acids. This absence is conspicuous, as a salt of these two metals Pierre Calaminaire, a carbonate of zinc, was taken to be a semi-metal at the time) had been known since the mid-seventeenth century—see hgure 8.3 in the previous chapter. [Pg.156]


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