420 



SMITH S INTERMEDIATE CHEMISTRY 



dilute alcohol, in the form, for example, of " hard " cider (fer- 

 mented apple juice), is allowed to trickle over shavings in a barrel. 

 The shavings are inoculated with the B. aceti by preliminary 

 wetting with vinegar. Holes in the sides admit a plentiful sup- 

 ply of air, to the action of the oxygen of which the liquid is ex- 

 posed by being spread over the surface of the shavings: 

 C 2 H 5 OH + 2 -> CH 3 .COOH + H 2 O. 



The liquid (vinegar), which issues at the bottom, contains from 

 5 to 15 per cent of acetic acid, besides coloring and flavoring 

 matters derived from the fruit juices. 



Pure acetic acid may be prepared by distilling the vinegar 

 repeatedly. It is derived more cheaply, however, from the liquid 

 distillate obtained by heating wood in the manufacture of char- 

 coal. Large quantities are used in the manufacture of various 

 synthetic organic products (see, for example, p. 480). 



tractive Distillation of Wood.^^fhen dry wood is 

 in iron retorts in absence 6? airythe compounds which 



it contains are decom- 

 posed. Much of the 

 carbon remains in the 

 form of charcoal. The 

 vapors which pass off 



j u ^ ^ (through the pipe on 



the right, Fig. 103) 



FlG - 103 ' deposit, when cooled, 



much liquid material. The uncondensed gases are combustible 

 and are used for heating the retorts or other similar purposes. 

 Hard wood furnishes, approximately, 25 per cent of its weight 

 of charcoal, 25 per cent of gases, and 50 per cent of liquids. 

 The liquid contains acetic acid (10 per cent), m,e,t-hy1 alcohol 

 J2H 3 OH or wood spirit (3 per cent), a complex, tarry mix- 



