258 INTRODUCTION TO GENERAL SCIENCE 



fresh air by night as well as by day. See Section 19, Ven- 

 tilation and Heating of Buildings. 



References : 



1. 1501 : 223-230. Dangers of Impure Air. 



2. 1503 : 387-388. Need of Ventilation. 



3. 1702 : 66-71. Air and Ventilation. 



4. 1710 : 16-22. Substances in the Air. 



5. 1710 : 40. Dangers from Air Vitiation. 

 6. 1901 : 230-234. The Air and Disease. 



a. 1505 : 80-86. Hygienic Habits of Breathing. 



6. 1506 : 153-156. Impurities in the Air. 



c. 1507 : 206-209. Evils of Indoor Life. 



d. 1509 : 182-184. Effects of Respired Air. 



e. 1509:189-192. Dust and Disease. 



/. 1510 : 40-42. Hygiene of Respiration. 



g. 1511 : 128-129. Object and Need of Ventilation. 



h. 1904 : 63-67. Care of Consumptives. 



i. 1905 : 33-38. Impurities in Air, their Effects and Tests. 



Experiment 83.* Test for Bad Air. 



Apparatus: A twenty-ounce glass stoppered bottle, glass 

 measure graduated in cubic centimeters, medicine dropper 

 graduated to hold one third of a cubic centimeter. 



Materials : Limewater solution (pure water left in contact 

 with slaked lime until saturated. Dilute the clear decanted 

 liquid with 99 times its own volume), phenolphthalein solu- 

 tion (dissolve one part of phenolphthalein in 500 times its 

 own weight of 50 per cent alcohol). 



a. Fill bottle with pure water, and empty it in the place 

 where the air is to be tested. This will insure the bottle being 

 filled entirely with the air of the room. Add 10 c.c. of lime- 

 water solution and one-third c.c. of phenolphthalein solution, 



* After Dr. J. B. Cohen, modified. 



