CHAPTER XXIX 

 THE HYDROCARBONS AND THEIR DERIVATIVES. FLAME 



THE compounds of carbon and hydrogen are called the hydro- 

 carbons. Hundreds of different hydrocarbons, containing differ- 

 ent proportions of the two elements, are known. The natural 

 oil petroleum is a mixture of many substances of this class. 



The hydrocarbons fall into several distinct series, the chief 

 one of which contains methane CH4 as its simplest member. 

 On account of the fact that certain members of this set are found 

 in paraffin, it is commonly known as the paraffin series. For 

 the reason that in this series the carbon has all its four valences 

 employed, the members are also called the saturated hydrocar- 

 bons. 



Paraffin or Saturated Series of Hydrocarbons. The 



following is a list of the names, formulae, and boiling-points of 

 seven of the simplest hydrocarbons of this series, and of two of the 

 higher members of the series : 



Methane CH 4 b.-p. - 164 Hexane C 6 H U b.-p. 71 



Ethane CzHe - 89.5 Heptane C 7 Hi 6 99 



Propane CaHs -37 Hexadecane Ci 6 H 84 287.5 



Butane C 4 Hi + 1 m.-p. 18 



Pentane C 5 H 12 35 Pentatriacontane 0^72 m.-p. 74.7 



After the first four, the names are based on the Greek numerals 

 corresponding to the number of carbon atoms in the molecule. 

 On comparing the formulae, we observe that in each, the number of 

 units of hydrogen is equal to twice the number of carbon units 

 plus two. The general formula is therefore C n H 2 n+2. The series 

 affords a striking illustration of the law of multiple proportions. 

 We note, further, that the first four are gases at the ordinary tem- 



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