Structure of Simpler Organic Compounds. 51 



pounds of this type containing one up to an infinite 

 number of carbon atoms. All substances with structures 

 of this type can be represented by the general formula 

 C n H 2n+2 . A large series of such substances is actually 

 known ; they are designated paraffins, and their chemical 

 and physical properties will be considered in some detail 

 later. 



Now, in the formulae of the hydrocarbons given 

 above, it will be noticed that no carbon atom is directly 

 bound to less than two hydrogen atoms, and all the carbon 

 atoms are united to one another in a " straight " chain. 

 When, however, compounds of this series contain four or 

 more carbon atoms, it is possible to construct the formulas 

 in another way and to maintain still the quadrivalency 

 of the carbon atom. Thus, it is possible to represent a 

 hydrocarbon with four carbon atoms by the formula 



H H H 

 H C C C H 



1 



H H 



H 



Both this formula and the one given above of a hydro- 

 carbon with four carbon atoms represent a substance with 

 the empirical formula C 4 H 10 . Now it has been found 

 that two substances differing from one another in their 

 properties actually exist, and are examples of what has 

 been designated " isomerism " (see p. 47). The physical 

 properties of the two " isomerides " are not identical, and 

 the derivatives which can be obtained from them by 

 various chemical reactions are different. The first formula 

 given (that is, the " straight-chain " formula) represents the 

 substance which is known as butane, and the second (or 



