10 INTRODUCTION. I. 



The Paraffin Series. The Olefine Series. 



CA c 4 H s 



H H C H 



I II 



H C H C H 



H C II H-C H 



I I 



H C-H H C H 



i 



In each of these two series it will be observed that every 

 member differs from the one preceding it by CH. 2 and its 

 graphical formula is written by simply adding a carbon atom 

 attached to two hydrogen atoms between the terminal groups 

 in the chain. A similar power of linking together is shown by 

 the carbon atoms in other carbon compounds. It will be 

 noted from the examples given that the linkage of two carbon 

 atoms together may be by one or two of their combining 

 affinities. 



The presence of one pair of doubly linked carbon atoms is 

 the characteristic of the olefine series. In another series, the 

 acetylene, trebly linked carbon atoms occur, e.g., HC 7 ^ CH, 

 acetylene itself. It is to this power of the carbon atoms of 

 linking themselves together that the possibility of the existence 

 of such an immense number of carbon compounds is due. No 

 other element shows the same power, unless it be silicon, a 

 few compounds of which of the above type have been prepared. 



In consequence of this unique property of carbon it is now 

 customary to place the study of carbon compounds in a sepa- 

 rate division of chemistry. To this branch of knowledge the 

 name of organic chemistry has been given, and although it h 

 of comparatively recent growth it has already attained vast 

 dimensions. 



A very large number of the compounds present in the bodies 

 of plants and animals are made up of compounds of the four 



