SOME CHEMICAL CONCEPTS 127 



Thus 



H H 



i I ^0 

 H C G Cf 



I ! NDH I | | X OH 



H H 



Propionic Acid. Butyric Acid. 



and so forth. 



This does not end the degree of complexity of the 

 formation of organic compounds. The formula for 

 Butyric Acid, for instance, adding up the Carbons, 

 Hydrogens, and Oxygens, is C 4 H 8 O 2 , but the formula 

 can also be written 



in which case you get a substance with different 

 properties, known as Isobutyric acid. When three 

 more CH 2 groups are added, you ggt a body called 

 Heptylic Acid. 



It is possible to write no fewer than seventeen 

 different structural formulae for Heptylic Acids satis- 

 fying the necessary conditions, though the formula 

 is a simple one (C 7 H 14 O 2 ), and of these seventeen 

 hypothetically possible bodies nine are actually 

 known. The number of hypothetically possible 

 acids from stearic acid, which is far from being the 

 most complex of the series known (C 18 H 36 O 2 ), can be 

 imagined. 



