220 COMMON SUBSTANCES 



4. What is glass? Of what substances is glass made? How 

 are these compounds treated to form glass? Name as many uses 

 of glass as you can. What two properties make it valuable? 



5. Of what substance is wood largely composed ? What ele- 

 ments are present in this substance? Name other things that 

 occur in some woods. Of what are ashes formed ? 



6. From what is cotton cloth made ? What then is the chemi- 

 cal composition of cotton cloth, i.e. what elements are present? 



7. Of what is paper made ? Describe the process of making 

 paper. What elements does it contain ? 



8. Of what is coal formed? How was it formed? What 

 element constitutes the larger part of hard coal ? What other ele- 

 ments are present? Distinguish anthracite and bituminous coal. 



9. Describe the making of illuminating gas. What other 

 substances are formed at the same time ? Of what elements is 

 illuminating gas largely composed? 



10. What is petroleum? What substances are obtained 

 from it? 



11. Name some important substances that are formed from 

 coal tar. 



12. What sort of a mixture is an explosive? Show how 

 explosive mixtures may be used to exert great force. State the 

 composition of gunpowder ; of gun cotton ; of nitroglycerin. 



13. What are the five classes of foods used by man? Name 

 some elements that are common in the body. Of what use are 

 carbohydrates in the system ? 



14. Name some common fuels. What two elements do they 

 all contain ? 



