122 LABOEATOKY MANUAL 



and introduce into it a burning splinter. Does the 

 splinter continue to burn as brightly as in the air? 

 What does this indicate? 



Air expired in ordinary breathing has lost about 

 one-fourth of the oxygen contained in inspired air. 



Exercise 81. School Ventilation. 

 Object: To determine the efficiency of the room 

 ventilation. 



Apparatus 



Tape measure 



Directions: For a sufficient air supply most author- 

 ities agree that an individual requires 300 cu. ft. of 

 space with 1,800 cu. ft. of air per hour. 



With the tape measure determine the dimensions of 

 the laboratory. From the dimensions what is the 

 volume of the laboratory in cubic feet? 



Divide the cubic contents of the laboratory by the 

 number of people in the room. How does the quotient 

 compare with the number of cubic feet of space each 

 individual should have? 



What is the method of ventilation in the school 

 building? Learn from those in authority the number 

 of times per hour the air is changed in the room. 

 Compute from this data the number of cubic feet of 

 air each person receives per hour. Is this sufficient for 

 the individual? 



Follow the same directions in computing the volume 

 of your session room. Divide the cubic contents by 



