64 HOUSEHOLD BACTERIOLOGY 



Experiment III. Take seven clear glass bottles, 

 Experiments number or mark each in some way. (Small laboratory 

 Bacteria flasks with flat bottoms are convenient for this pur- 

 pose.) Put into each one-half cup or less of milk or 

 grape juice. 



Leave No. I open in a warm room, not in direct 

 sunshine. 



Fit No. 2 with a full plug of cotton wool about one 

 inch long. Put with No. i. 



Have No. 3 like No. i, but place immediately in an 

 ice box. 



Drop into No. 4 one tablet or "saloid" of corrosive 

 sublimate. This can be bought of a druggist. Mark 

 it "Poison." Plug like No. 2 and place it with No. i. 



Plug No. 5 with cotton wool like No. 2. Put it into 

 a steamer and steam for thirty "minutes three days in 

 succession. Place it with No. i. 



Fit No. 6 with a tight cork. Remove the cork, but 

 place it with the bottle in the steamer and steam as 

 you did No. 5. Cork each bottle while the steam is 

 coming out. As the cork cools and shrinks, tighten it. 



Put a cotton wool plug into No. 7 and heat for half 

 an hour from 155 F to 165 F. 



After completed preparation, keep all but No. 3 

 under the same conditions and note any changes that 

 occur. Test the open bottles with strips of blue litmus 

 paper from the druggist's. See if the contents change 

 the paper any more rapidly or completely after two or 

 three days than at first. Test by smell and taste all 



