Classification, generally historical development

Although such an understanding of the reaction mechanism is in principle applied in the theory of pericyclic reactions, the above general picture is in this case slightly complicated by the specific (introduced in the course of historical development) classification of reaction mechanisms in terms of concertedness and/or nonconcertedness. Concerted reactions are intuitively understood as those reactions for which the scission of old bonds and the formation of the new ones is synchronised, whereas for nonconcerted reactions the above bond exchange processes are completely asynchronised. Moreover, since the above asynchronicity is also intuitively expected to induce the stepwise nature of the process, the nonconcertedness is frequently believed to require the presence of intermediates, whereas the concerted reactions are believed to proceed in one elementary step. 

Dyestuff Recognition Tests for Historic Fabrics. Methods have been developed specifically for identifying general dye classifications on historic textile artifacts. Procedures outlined by Rice (14) were followed in this portion of the study. 

In 1 b 2 (p 3) we have, outlined in very general terms the historical development of the stability question We will now go more extensively into the question because it provides the basis for a logical classification of colloid science and this book is therefore also sectionalized on this basis ... 

Chapters 6 and 7 are dedicated to the table s chemical content, especially the conceptual framework employed in its construction. Chapter 6 will deal with the classification s most general principle, the principle of classification according to composition. Classification according to composition is not a universal mode of chemical classification, but a historical one. Based on our principal discussion of the modem concept of chemical composition in part I, three of the historical preconditions of this classification will be studied in this chapter 1) the kind of chemical substances presupposed by this classificatory principle that is, pure chemical substances which became the subject of chemical practice in the early modem period 2) the demarcation of the modem notion of composition from earlier concepts of the constitution of substances and 3) the development of the analytical method of procuring certain knowledge of chemical composition. 

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