A Different World Plant Materials

1 It should be noted that the following account largely applies to animal materials, too. We concentrate here on plant substances for pragmatic reasons, but also because that area was much more elaborated than that of animal chemistry. 

The subsequent chapters 12 through 16 examine changes in the classification and ontology of plant materials. In so doing, they focus on the way chemists ordered plant materials in contexts of conceptual inquiries, and on the changing meaning and identity of plant materials in these specific contexts. 

Chapter 12 discusses early eighteenth-century chemists interest in the most simple elements or principles of plants, and in plant analysis that aimed to separate the simple principles. It further illuminates early eighteenth-century chemists demarcation of the class of ultimate principles of plants, as well as other kinds of chemical 

Given the role played by horticulture and breeding as a practical context of classification in eighteenth-and nineteenth-century botany and zoology, one may claim that even in these areas constitutions of single objects to be classified were not entirely independent of practice and understanding. 

The analysis of the classification of plant materials in the Methode de nomenclature chimique, presented at the beginning of chapter 14, creates an important link between parts II and III of this book. This analysis first shows the ambition of Lavoisier and his collaborators to extend classification according to composition to plant substances, and, second, their failure in terms of collective acceptance. The next section of the chapter continues this analysis of their failure inasmuch as it points out the theoretical limits of the Lavoisierian analytical program. As Lavoisier s theory of the elemental composition of organic substances did not include the assumption of stoichiometric organic compounds, it was unsuitable as a working tool for the envisioned analytical mode of identification and classification of organic compounds. 

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