352 ALCOHOL 



ALCOHOL 



The more important mono-hydric alcohols used in medi- 

 cine and pharmacy are : 



Methyl-alcohol, CH 3 .OH, from distillation of wood. 

 Ethyl- C 2 H 5 .OH, fermentation of grape sugar. 

 Propyl- ,, C 3 H 7 .OH, grapes. 



Butyl- C 4 H 9 .OH, beet. 



Amyl- C 5 H n .OH, potatoes. 



These alcohols are hydroxides of the radicles of the 

 methane or marsh gas series (CH 4 ). In their production 

 the hydrocarbon has one of its atoms of hydrogen (H) 

 displaced by the radicle hydroxyl (OH). Thus, methane 

 (CH 4 ), losing one atom of H, and assuming one OH, becomes 

 CH 3 .OH, or methyl-alcohol, popularly known as wood 

 spirit. Ethane (C 2 H 6 ), losing one atom of H, and taking 

 up one OH, becomes C 2 H 5 . OH, ethyl-alcohol, or spirit of wine. 

 Each of these alcohols, when oxidised by removal of H 2 , in 

 the form of a molecule of water (H 2 0), yields an aldehyde ; 

 while by substitution of OH for H, the aldehydes are con- 

 verted into acids. Thus, ethyl-alcohol (CH 3 .CH 2 .OH) is 

 converted into aldehyde (CH 3 COH), and thence into acetic 

 acid (CH 3 CO.OH). In each of the alcohols, moreover, the 

 H in the OH can be replaced by an alcohol radicle, when an 

 ether is formed ; thus, ethyl-alcohol (C 2 H 5 .OH) yields 

 common ether (C 2 H 5 .O.C 2 H 5 ). 



Absolute alcohol. Ethyl hydroxide (C 2 H 5 .OH), with not 

 more than one per cent., by weight, of water ; obtained by 

 the removal of water from less concentrated ethylic alcohol 

 and subsequent distillation. Specific gravity from 0'794 to 

 0-7969. Very volatile and hygroscopic at ordinary tempera- 

 tures (B.P.). Absolute alcohol is a mobile, colourless fluid, 

 with a spirituous odour, and an intensely fiery taste. It has 

 great amnity for water, takes it from any substance with 

 which it is in contact, and thus exerts its notable power of 

 preserving both vegetable and animal matters, 



Rectified spirit (spiritus rectificatus), or alcohol (90 per. 

 cent.). A liquid containing ninety parts by volume of ethyl 

 hydroxide, and ten parts by volume of water ; obtained by 



