HOUSEHOLD CHEMISTRY 97 



laundry use, what very commonly is done before making use 

 of soap in washing clothes? Test with litmus paper a 

 solution of any washing powder at hand to determine its 

 nature. 



4. From reference books, or other sources, ascertain 

 what to do in order to remove from cloth (a) spots of com- 

 mon ink ; (6) coffee stains ; (c) paint spots ; (d) grass stains. 



5. How may varnished surfaces, whether polished or 

 waxed, be cleaned without harm to them ? How is tarnish 

 removed from metals, such as silverware? How do you 

 account for the blackening of silverware (a) by eggs; (6) 

 by contact with rubber ? 



6. Watch very closely the bleaching effect on small pieces 

 of cheap calico, and upon stains on white goods, when these 

 are dipped repeatedly into a solution of bleaching powder 

 to which strong vinegar is added. Notice the odor of the 

 bleaching powder. What is the chemical agent active in 

 the bleaching? 



ACIDS, BASES, AND SALTS 



1. Making use of small strips of litmus paper test the 

 effect on it of vinegar and of fruit juices (as lemon, orange, 

 grapefruit, cherries, etc.) ; of ammonia water, limewater, 

 and drinking water ; and of solutions of baking soda, washing 

 soda, borax, soap, and common salt. Arrange these sub- 

 stances in columns under the headings acid, alkaline, and 

 neutral, according as the litmus paper is turned red, or blue, 

 or is unaffected in color. 



To the list as above add a half dozen or more tests of 

 other solutions. 



