88 CHEMICAL PROPERTIES AND COMPOSITION 



i. The elements bring the chemical properties that 

 they show in simple binary compounds into more complex 

 derivatives. This appears most clearly with regard to 

 valency, which for carbon in binary compounds such as 

 CH 4 is four ; Kekule then proved that this fundamental 

 property exists also in more complex compounds, and 

 so laid the foundation for the study of chemical con- 

 stitution. 



2. The elements exercise in their compounds other 

 influences, which fall off with distance, and modify the 

 original character of the element influenced in a way that 

 can be brought under general rules. A suitable example is 

 the action of oxygen in organic compounds in decomposing 

 and hastening reaction, and shows that changes almost 

 always take place in its neighbourhood ; so that, e. g. 

 breaking up the carbon linkages by oxidation of ketones 

 always takes place at the carbon atom which carries the 

 oxygen atom. 



3. Sometimes grouping of elements leads to entirely 

 new chemical properties which could not even be distantly 

 expected from the rules contained in the two preceding 

 paragraphs. This peculiar behaviour is seen, e. g. in the 

 sudden appearance of a strong basic character in ammonium 

 derivatives such as (H 3 C) 4 NOH, which rivals caustic potash 

 in properties. 



i. THE ELEMENTS BRING THE CHEMICAL PROPERTIES 

 THAT THEY SHOW IN SIMPLE BlNARY COMPOUNDS INTO 

 MORE COMPLEX DERIVATIVES. 



To bring out this first relation as clearly as possible let 

 us consider first the indications by which the chemical 

 character is distinguished in simple binary compounds. 



In the first place there is the valency : sometimes in 

 the elements that play the chief parts in organic chemistry, 

 carbon, hydrogen, or oxygen this is so constant, in the 

 most diverse compounds, that it is a reliable guide to 



