SUBSTITUTION PRODUCTS OF THE HYDROCARBONS 29 



Methyl Alcohol {Wood Alcohol) 



Methyl alcohol, CH3OH, which is hydroxy-methane, is com- 

 monly known as wood alcohol because it is produced by the de- 

 structive distillation of wood. When wood, better the hard 

 woods such as beech or maple, is heated in closed retorts, or in 

 compact piles covered with earth, so that no air, or only a small 

 amount, has access to it, the wood is not burned but is decom- 

 posed by the heat. Such a process is termed destructive distillation. 

 As a result of this heating the wood is decomposed into gaseous 

 and liquid products and a residue of carbon or charcoal is left. 

 The gaseous products contain some ammonia, but mostly mix- 

 tures of gaseous hydrocarbons. The liquid distillate contains 

 methyl alcohol together with other compounds to be considered 

 later, of which acetic acid (vinegar acid) is the most important. 

 The crude distillate is acid in character and is known as pyro- 

 ligneous acid. It is dark colored because of tarry compounds 

 contained in it, most of which separate as an oily layer, and 

 can be removed as such. To obtain the methyl alcohol alone 

 from this crude acid distillate the latter is neutralized with 

 alkali (lime or caustic soda) and redistilled. The neutralization 

 converts the acetic acid into a non-volatile salt so that by the 

 redistillation the alcohol is separated from this compound. 

 By further purification from the other compounds present, and 

 by fractional distillation through what is known as a column 

 still, methyl alcohol of 95 per cent purity is obtained. Such 

 high grade methyl alcohol is known in this country as Columbian 

 Spirits. Absolute or 100 per cent methyl alcohol may be ob- 

 tained by forming a crystalline compound with calcium chloride ; 

 and this, when filtered off and air dried, is decomposed with 

 sulphuric acid and distilled. 



Another source of methyl alcohol is the dry residue obtained 

 in the manufacture of beet sugar. When the juice of the 

 sugar beet is concentrated and then the sugar crystallized out 

 as much as possible, a sirupy residue containing considerable 

 solid matter remains. This still contains more or less sugar, 



