Artificial classifications

Linnaeus, the founder of modern classification of organisms had completely artificial classes to accommodate his genera. But already by the end of the 18th century the idea of Natural Classification arose. The difference, and this is a basic and important difference, is that artificial classifications are filing cabinets of the human mind, while natural classifications are supposed to reflect Nature s Own Order, the order that can be inferred to exist in Nature. 

This chapter has argued for the critical role of interfacial defects in solids. We have favored an artificial classification into three primary types of interfacial defects, namely, surfaces, stacking faults and twins, and grain boundaries. In each of these cases, it has been argued that a continuum description of the energetics of such... 

This paradox can be resolved by turning to second quantization where the basic structure of the formalism ensures that no artificial classification of electrons is possible or necessary. We shall investigate under which conditions one arrives at Eq. (15.7) or Eq. (15.12), using a second quantized many-body Hamiltonian. 

The pragmatic compromise that had prevailed since the 1840s was not displaced by Mendeleev s periodic system. Hybrid natural/artificial classifications were still largely used in French chemistry textbooks up to the first decades of the twentieth century, while the ideal natural classification remained in a far distant future (Figure 5.2). While this general attitude may partially explain why most chemistry authors obviated Mendeleev s ideas in their textbooks, it nevertheless raises a question How is it that a few authors paid attention to an imperfect and unfeasible classificatory system ... 

Thus, the periodic system was introduced as part and parcel of a French battle for the atomic theory. When the atomic weight notation and system supported by Wurtz became compulsory in the official curricula for secondary education, a new generation of textbook authors clearly announced the adoption of the atomic theory in their titles. However, only a few of them included the chemical properties observed by a Russian chemist in the package of the atomic theory. And even in their secondary school and university textbooks, the old hybrid natural/artificial classification proved extremely resilient. 

These issues are explored in the following four sections. First, we study the introduction of artificial classifications (mostly those suggested by the French chemist Louis-Jacques Thenard (1777-1857)). Then, we discuss the mutable character of these arrangements and the changes introduced by the authors and translators of Spanish textbooks. The third section deals with the advent of the natural classifications, focusing on the original proposal suggested by the Catalan pharmacist Josep Antoni Balcells (1777-1857). Finally, we provide a description of a Spanish textbook written at almost the same time as Mendeleev s Principles of Chemistry. 

In 1875, just a few years after Mendeleev had pubhshed his periodic classifications, the pharmacist and professor of chemistry Rafael Saez Palacios (1808-1883) wrote a two-volume treatise on chemistry intended for students of pharmacy. Saez had already published several translations of leading chemistry textbooks, including Berzelius s treatise and a number of French books that had adopted natural classifications. Like many other textbook authors, he devoted a full section to classifications before the chapters on metals, describing Thenard-Regnault s and Berzehus s artificial classifications as well as many examples of natural classifications. He... 

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