MANUAL FOR SUGAR GROWERS. 



135 



as to retain a thin film of moisture on the surface 

 of each disc ; the wash in its downward course over 



OUTtET FOB ALCOHOL 



PIG. 20. Diagram of continuous still. 



the perforated discs meets the ascending hot va- 

 pours generated by means of steam admitted from 

 a steam-boiler not shown in the figure. The more 

 volatile portion of the wash the alcohol escapes 

 through the pipe into the worm of the condenser, 

 where it is condensed as already described. The 

 less volatile portion passes downward into the cham- 

 ber at the bottom of the rectifying-column, whence 

 it is run off as it accumulates. 



The exhausted residue from which the spirit has 

 been distilled is known as dunder. It contains vari- 

 ous mineral matters, as potash, phosphoric acid, etc., 

 together with any sugar which has escaped fermen- 

 tation. A certain quantity of it is usually employed, 

 instead of water, in setting up fresh wash for fer- 

 mentation, the unfermented sugar being thus saved, 



