206 ACIDS, ALKALIES, AND CLEANING 



2. Why is it not enough to wash clothing in cold water, even with 

 soap? Why is it not enough to use hot water, without soap? 



3. Commercial laundries sometimes use acids, such as hydrochloric 

 acid, for the washing of clothing; why is this not a good practice? 

 What fabrics especially are injured? 



4. Why should wool be washed with mild soaps, and in warm, but 

 .not hot, water? 



5. How could you test a soap for an excess of alkali? 



6. Why does not a soap give a lather as quickly in well water as in 

 rain water? 



7. Why is " blueing" used in the laundering of white goods? 



8. Why do not men make soap out of petroleum and lye? 



9. Why should oily cloths piled in a heap take fire spontaneously, 

 while if outspread they do not? 



10. What causes the "scum" that forms on the surface of an open 

 can of paint? Gasoline and benzine are cheaper than turpentine; are 

 they good substitutes for it? Why? 



