80 



WATER 



Overflow 



Distillation consists in heating a liquid until it boils, 

 and then passing the vapor through a condensing appara- 

 tus to convert it back into the liquid state. The solid 



substances, such 

 as salt, limestone, 

 gypsum, etc., do 

 not boil off, but 

 remain behind in 

 the boiler. The 

 form of distilling 

 apparatus much 

 used in laborato- 

 ries is shown in 

 Fig. 66. 



FIG. 66. 

 Distillation of Water; Liebig's Condenser. The Condenser IS 



known as Liebig's 



condenser, after the celebrated scientist of that name. It is of glass, 

 and consists of an inner tube for condensing the vapor, and an outer 

 jacket for the cooling liquid, which 

 is usually water. For distillation 

 on a larger scale a boiler and 

 a "worm" condenser are used 

 (Fig. 67). 



Other liquids may be distilled 

 like water. Thus, while water 

 boils at 100 C., alcohol boils at 

 79 C. If a mixture of alcohol and 

 water is distilled, the alcohol boils FIG. 67. 



off first, and the two may thus be Large Still and Worm Condenser. 



Boiling removes the temporary hardness of water, and kills the 

 germs. Since the taste of natural water is due to the dissolved gases 

 and solids it contains, distilled water tastes very "flat." Boiled 



