HYDROCARBONS. 261 



carbons are neutral substances, behaving rather indifferently 

 towards most other chemical agents, ^lost of them are, how- 

 ever, oxidized by the oxygen of the air, by which process liquid 

 hydrocarbons are often converted into solids. 



Hydrocarbons of the paraffine or methane series. The hydrocar- 

 bons having the general composition C n H 2n + 2 are known as 

 paraffines, the name being derived from the higher members of 

 the series which form the paraffine of commerce. The following 

 table gives the composition, boiling-points, etc., of the first 16 

 members of this series : 



B. p. Sp. gr. 



Methyl hydride or methane, CH 4 , ~| 



Ethyl hydride or ethane, ^2^6' ] Gases. 



Propyl hydride or propane, C 3 H 8 , j 



Butyl hydride or butane, C 4 H 10 , C 



Amyl hydride or pentane, C 5 H 12 , 30 0.628 



Hexyl hydride or hexane, C 6 H U . 68 0.669 



Heptyl hydride or heptane, C 7 H 16 , 93 0.690 



Octyl hydride or octane, C 8 H 18 , 118. 0.726 



Nonyl hydride or nonane, C 9 H 20 , 138 0.741 



Decyl hydride or decane, C 10 H 22 , 158 0.757 



Undecyl hydride or undecane, C U H 24 , 180 0.766 



Dodecyl hydride or dodecane, C 12 H 26 , 198 0.778 



Tridecyl hydride or tridecane, C 13 H 28 , 218 0.796 



Tetradecyl hydride or tetradecane, C U H 30 , 236 0.809 



Pentadecyl hydride or pentadecane, C 15 H 32 , 258 0.825 



Hexadecyl hydride or paraffine, C 16 H 34 , 280 

 etc. 



The above table shows that the paraffines form a homologous 

 series; the first 4 members are gases, most of the others liquids, 

 regularly increasing in specific gravity, boiling-point, viscidity, 

 and vapor density, as their molecular weight becomes greater. 



The paraffines are saturated hydrocarbons, the constitution 

 of which has been already explained; they are incapable of 

 uniting directly with monatomic elements or residues, but they 

 easily yield substitution-derivatives when subjected to the action 

 of chlorine or bromine. 



Most of the paraffines are known in two (or even more) modi- 

 fications; there is therefore another homologous series of hydro- 

 carbons of the same composition as the above normal paraffines, 

 which show some difference from the normal paraffines in boiling- 



