238 



VINEGAR, CIDER, AND FRUIT-WINES, 



still. Fig. 57 shows the arrangement of the rectifying vessels. 

 The stop-cock introduces a certain quantity of water which passes 



Fig. 56. 



Fig. 57. 



from the upper to the middle basin and then to the lower one 

 where it runs off. By its passage through the basins the more 

 condensable vapors, consequently also those of water and acetic 

 acid, are condensed, so that the non-con- 

 densed portion which is only condensed in 

 the cooling apparatus 6, Fig. 56, possesses a 

 certain strength, it generally showing a spe- 

 cific gravity of 0.965. At c, Fig. 56, imme- 

 diately at the end of the discharge-pipe, is 

 placed a small accurate aerometer, so that 

 the specific gravity of the distillate can at 

 any time be read off. 



Distillation is continued until the specific 

 gravity is 1, all the distillable bodies having 

 then passed over. Before being brought into commerce the crude 

 wood-spirit thus obtained is generally subjected to purification, 

 which will be described later on. 



If distilled wood-vinegar is to be obtained, for instance, for 

 the preparation of crude lead acetate, distillation is continued, 

 after changing the receiver, until oily drops appear at c,this being 

 an indication of portions of the tar now passing over. Firing is 

 then interrupted, and after allowing the apparatus to cool off 

 somewhat, the tar remaining in the still is drawn off into the vat 

 (1, Fig. 56. 



The tar is then combined with the upper and lower layers of 



