64 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Pure Methyl Alcohol. 



Commercial methyl alcohol contains acetone. By dissolving 

 anhydrous oxalic acid (prepared by heating oxalic acid at 100) in the 

 boiling spirit, methyl oxalate is formed ; it separates in crystals on cool- 

 ing. The crystals are filtered off, washed free from acetone with water, 

 and then decomposed into oxalic acid and methyl alcohol by boiling 

 with water or ammonia. Methyl alcohol is obtained on distillation and 

 is dehydrated by distilling over quicklime (see under ethyl alcohol). 



Pure methyl alcohol may also be obtained by boiling commercial 

 methyl alcohol with anhydrous calcium chloride. Calcium chloride 

 crystallises out in combination with methyl alcohol as CaCl 2 +4CH 3 OH 

 from the saturated solution on cooling. The crystals are drained from 

 the mother liquor and are decomposed by heating ; methyl alcohol is 

 evolved and is collected. 



The acetone may also be removed by passing chlorine into it form- 

 ing trichloracetone. The methyl alcohol is separated by fractional 

 distillation. 



Properties. 



Methyl alcohol is a colourless liquid which boils at 66 and has 

 a sp. gr. of 797 at 15. It closely resembles ethyl alcohol in its 

 properties, but it does not give the iodoform reaction. 



ETHYL ALCOHOL. 



Preparation. 



Ethyl alcohol is obtained by the fermentation of sugar by yeast 

 and occurs in all fermented liquids such as wine and beer. It is made 

 chiefly from potatoes and cereals, the starch being first converted into 

 the sugar, glucose, which is fermented by the yeast and changed into 

 alcohol and carbon dioxide. 



1. Rectified Spirit. 



The alcohol produced by fermentation is separated from the fer- 

 mented liquor by distillation. The distillate is then fractionally re- 

 distilled, or rectified, so as to separate as much water as possible and 

 the greater part of the higher alcohols. The product is rectified 

 spirit. It contains about 84 per cent, by weight of ethyl alcohol and 

 has a sp. gr. of 0-838 at 15. 



2. Methylated Spirit. 



The rectified spirit is denatured and rendered unfit for drinking 

 purposes by the addition to it of one-ninth of its volume of wood spirit 

 and three-eighths of I per cent of mineral naphtha or paraffin oil. 



Since 1905 methylated spirit has been obtainable in approved 

 scientific institutions free of duty and free from mineral naphtha. 



