MANUFACTURE OF WOOD-VINEGAR. 233 



tially of smoke). Its specific gravity varies between 1.018 and 

 1.03. When mixed with water it frequently becomes turbid. 



Wood-vinegar is a mixture of very dissimilar bodies. Besides 

 its principal constituent, acetic acid, it contains several other acids 

 belonging to the series of fatty acids with the general formula 

 CnH 2 nO 2 ; further wood-spirit, acetone (see below), metacetone 



C 6 H 10 O, methyl acetate C J?f?lo, aldehyde, dimethyl acetal 



^2 X1 S ) 



) Of^TT 

 C 2 H 4 > oQjj 3 ? furfurol, allyl alcohol C 3 H G O, small quantities of 



ammonia and of methylamine CH 3 ,H 2 !N", and finally plenols and 

 guaiacols ; besides empyreumatic resins. 



To carbolic acid, one of the plenols, is due the property of 

 wood-vinegar to preserve meat and other organic substances. 



On mixing wood-vinegar with soda-lye it becomes turbid, but 

 on a further addition of alkali soon clarifies again and acquires a 

 dark brown color, a brown body being separated. On mixing it 

 with 5 to 10 per cent, by volume of concentrated sulphuric acid 

 it becomes turbid and after 24 hours the greater portion of the 

 tar separates in fine drops. Potassium bichromate colors wood- 

 vinegar brown, and nitrate of silver is reduced at an ordinary 

 temperature, a silver mirror being produced (this reduction is due 

 to the content of aldehyde and creasote). 



In the distillation the more volatile bodies, of course, pass over 

 first; they form a yellowish fluid which contains wood-spirit, 

 acetone, etc. Then follows a turbid slightly acid water of a 

 yellowish color ; it gradually becomes richer in acid, but remains 

 yellowish to the end. The wood-vinegar boiling in the retort 

 constantly becomes darker, and finally a clear dark brown fluid of 

 a syrupy consistency and of an acid, and at the same time bitter, 

 taste remains. 



In order to understand what follows it will be necessary to give 

 the more important properties of the most valuable constituents 

 wood-spirit and acetone occurring, besides acetic acid, in crude 

 wood- vinegar. 



