240 VINEGAR, CIDERj 



column of coke the wood-vinegar is poured in an uninterrupted 

 fine spray, while in the space between the bottom and the grate a 

 slow current of air heated to 104 F. is constantly blown in 

 through a nozzle. The empyreumatic oils mixed with the wood- 

 vinegar are oxidized by the oxygen of the warm air, and, in con- 

 sequence, the temperature in the interior of the column of coke rises 

 to 122 F., and more. (The pipe is protected from cooling oif by 

 a thick layer of felt.) The products of the oxidation of the 

 empyreumatic oils are partially of a resinous nature and adhere 

 to the coke, and partially volatile. The acetic acid running oif 

 through an S -shaped pipe on the bottom of the pipe is clear, of a 

 pure acid taste and suitable for the preparation of all the acetates 

 as well as of acetic acid. The very slight empyreumatic odor 

 completely disappears by forcing the product through a pipe filled 

 with pieces of animal charcoal freed from lime. The vinegar thus 

 obtained is used for the table. Though a quantity of acetic acid 

 is carried off in the form of vapor by the warm dry current of 

 air, this loss can be prevented by passing the air through another 

 pipe filled with calcined soda or lime. 



For obtaining acetic acid for technical purposes, for instance, 

 for the preparation of aniline, acetate of lead, white lead, verdi- 

 gris, etc., where a slight empyreumatic odor and taste are of no 

 consequence, it is best to prepare calcium acetate and to decom- 

 pose the latter with crude hydrochloric acid. 



By saturating crude wood-vinegar with slaked lime a dark- 

 brown turbid solution is obtained, and much tar is separated, 

 especially with the use of an excess of lime. By evaporating the 

 filtered solution dark-brown rust-like flakes are separated and a 

 nearly black non-crystalline salt of a strong odor remains behind 

 which cannot be freed of its color and odor even by re-dissolving 

 it several times. Purification succeeds better with the use of 

 calcined soda for saturating the crude wood-vinegar, because the 

 sodium salt crystallizes readily and the greater portion of the im- 

 purities remains in the mother-lye. But even here it is not pos- 

 sible to obtain the salt pure by frequently repeated re-crystalliza- 

 tion. The calcium salt as well as the sodium salt can, however, 

 be obtained entirely colorless by boiling the solution with animal 

 charcoal, though it will not be completely freed from odor. 



