124 



GENERAL SCIENCE 



lake (Figure 108). Chicago no longer pours its sewage 

 into Lake Michigan but into the Mississippi River by 

 way of the Chicago " Drainage Canal " and the Illinois 

 River. 'Many small inland cities rely upon large wells 

 for their water supply, while the large inland cities take 



FIG. 109. Pure Water may be Obtained by Distillation. 



the water from near-by streams. Such water is usually 

 quite impure and should be filtered and in many cases 

 boiled before it is used for drinking purposes. 



Experiment 31. Arrange a Liebig condenser as shown in 

 Figure 109. Fill the flask with water that has been discolored with 

 foreign matter, such as coal dust, dirt, or ink. As the water 

 passes into steam and is again condensed it will be found to be as 



FIG. 110. Home Made Condenser. 



clear as water can be. This water is also free from solid matter. 

 In the absence of a Liebig condenser a condenser may be made by 

 arranging a large glass tube as shown in Figure 110. 



