ALCOHOLS. 481 



mixed with volatile oils. The triatomic alcohol glycerin is a normal 

 constituent of all fats or fatty oils, and is therefore found in many 

 plants and in most animals. 



Formation of alcohols. Alcohols are often produced by fermen- 

 tation (ethyl alcohol from sugar), sometimes by destructive distillation 

 (methyl alcohol from wood) : they are obtained from compound ethers 

 (which are compounds of acids and alcohols) by treating them with the 

 alkali hydroxides, when the acid enters into combination with the alkali, 

 while the alcohols are liberated according to the general formula : 



RTO> + KOH = 



Alcohols may be obtained artificially by various processes, as, for 

 instance, by treating hydrocarbons with chlorine, when the chloride 

 of a hydrocarbon residue is formed, which may be decomposed by 

 alkali hydroxides in order to replace the chlorine by hydroxyl, when 

 an alcohol is formed. For instance : 



C 2 H 6 + 2C1 == C 2 H 5 C1 + HC1. 



Ethane. Ethyl chloride. 



C 2 H 5 C1 + KOH KC1 -f C 2 H 5 OH. 



Ethyl Potassium Potassium Ethyl 



chloride. hydroxide. chloride. alcohol. 



Another method by which alcohols can be obtained depends on 

 the action of nitrous acid on amines containing radicals of the 

 methane series. For instance : 



C 2 H 5 NH 2 + NOOH = C 2 H 5 OH + 2N + H,O. 



Ethyl amine. Nitrous Ethyl 



acid. alcohol. 



Properties of alcohols. Alcohols are generally colorless, neutral 

 liquids ; some of the higher members are solids, none is gaseous at 

 the ordinary temperature. Most alcohols are specifically lighter than 

 water; the lower members are soluble in or mix with water in 

 all proportions ; the higher members are less soluble, and, finally, 

 insoluble. Most alcohols are volatile without decomposition; 

 some of the highest members, however, decompose before being 

 volatilized. 



Although alcohols are neutral substances, it is possible to replace 

 the hydrogen of the hydroxyl by metals, as has been shown above. 

 The oxygen of alcohols may be replaced by sulphur, when com- 

 pounds are formed known as hydrosulphides or mercaptans; these 

 bodies may be obtained by treating the chlorides of hydrocarbon 

 radicals with potassium sulphydrate. 



C 2 H 5 C1 -f KSH = KC1 + 

 31 



