CHAPTEK III 



SOME LEADING CONCEPTIONS IN ORGANIC CHEMISTRY 



THE number of chemical substances dealt with in this book is 

 not large, and the chemical reactions involved are not really 

 difficult to follow, even for those who do not possess an ex- 

 tensive acquaintance with organic chemistry, but some 

 understanding of the principles which underly the formulae 

 employed for expressing the composition and structure of 

 organic compounds, and of certain general reactions which 

 these latter undergo, is essential if the following chapters are 

 to be properly understood. 



For the benefit, therefore, of the general reader and of those 

 whose studies have been mainly confined to other branches 

 of knowledge, some space may be usefully devoted to the con- 

 sideration of certain fundamental conceptions in the science 

 of organic chemistry, and to the description of certain typical 

 substances and their characteristic reactions. 



According to the atomic theory of the structure of matter, 

 all material substances are supposed to consist ultimately 

 of atoms. A substance which can by some method be 

 divided into two or more kinds of matter differing from 

 one another and from the original substance is evidently a 

 compound of more elementary substances. But a substance 

 which has never yet been subdivided into other kinds of 

 matter having properties different from its own is regarded 

 as an element. A few such substances are known, and out 

 of them all others are found to be built up. If, then, we 

 imagine a particle of one of these ' elements/ e.g., of iron, to 



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