I. MARSH GAS DERIVATIVES (FATTY BODIES). 



FIRST GROUP. 



A. HYDROCARBONS, C n H 2n + 2 (MARSH GAS SERIES). 



COMPOUNDS consisting merely of carbon and hydro 

 gen are called hydrocarbons. The simplest compound 

 of this kind is marsh gas CH 4 , in which the four affin 

 ities of the carbon are saturated with four hydrogen 

 atoms. Marsh gas is the first member of an homologous 

 series of compounds, which have for their general for 

 mula C n H 2w + 2 . All facts as yet known justify the 

 conclusion that each of the four hydrogen atoms in 

 marsh gas has exactly the same value, and that, as far 

 as the properties of compounds are concerned, which 

 are produced by the displacement of hydrogen atoms 

 in marsh gas by means of other elements or groups of 

 atoms, it is immaterial which of the four hydrogen 

 atoms are displaced. Assuming this to be the case, 

 we see that for the first three members of this series, 

 CH 4 , C 2 H 6 , and C 3 II 8 , but one manner of constitution is 

 possible, viz.: CH 4 , CH 3 .CH 3 andCH 3 .CH 2 .CH 3 . There 

 can hence exist only one modification of each of these 

 three hydrocarbons. Isomeric compounds are not pos 

 sible. Of the fourth member, C 4 H 10 , there are two 

 different modifications possible: CH 3 .CH 2 .CII 2 .CH 3 and 



CH 3 .CH 3; of the fifth member, C 5 H 12 , there are 



three modifications possible ; of the sixth member, 

 five, etc. 



