174 



GENERAL SCIENCE 



per cent, the breathing becomes altered. At 10 per cent the color of 

 the face of a person breathing it becomes of a leaden hue, the heart 

 palpitates, bodily and mental activity become difficult. At 6 per cent 

 consciousness is lost; and death takes place when the percentage 

 of oxygen in the air is reduced to 3 or 4 per cent. 



The air that leaves the lungs contains more than 100 times as 

 much carbon dioxide as the air that enters. 



Laws Regarding Ventilation. The ideal room should have 

 about 600 cubic feet of air space for each person. Some States 

 require that each class room shall have 30 cubic feet of air per minute 

 for each pupil by an approved ventilation system, that each pupil 

 shall have 18 square feet of floor space and at least 200 cubic feet 

 of air space, and that all classroom ceilings shall not be less than 

 12 feet from the floor. What does the law require in your State? 

 Teachers and students should demand that these conditions be 

 met to safeguard their health. See that the law is lived up to. This 

 is one way of being a good citizen. 



Method of Ventilation. Air should never be allowed to become 

 stagnant. One of the best methods of ventilating a room is to flush 

 it out several times each day by opening the windows. This should 

 be done when the students are out of the room. This method 

 would be unwise if people were present, as the air is cooled, and a 

 cold draft and sudden cooling of the body might produce serious 

 results. 



Although the windows of the room should be opened during the 

 day, this does not mean the room should be closed at other times so 

 that no more fresh air is admitted. There should be a steady supply 

 of fresh air, heated to the proper temperature, and having the cor- 

 rect amount of humidity. 



A window board about 6 inches wide is another means of supply- 

 ing fresh air. The board is arranged so as fit the side of the 



