22 CHEMISTRY. 



barium and sulphur, barium sulphide; sodium and chlorine, 

 sodium chloride. Sometimes two sets of bodies are formed 

 by the same elements ; in such cases the name of the first 

 component receives the termination ous or ic, according to 

 the quantity of the second element combining with it. Thus 

 nitrogen and oxygen form two compounds, nitrous oxide 

 and nitric oxide the former containing more nitrogen than 

 the latter, or, if you please, the latter containing more oxy- 

 gen than the former. Further explanations of the methods 

 of naming compounds will be given in connection with the 

 section on oxides ( 62), and on acids, bases, and salts ( 79). 



QUESTIONS. 



[The numbers refer to the sections.] 



1. What is the difference between Chemistry and Natural Philosophy ? 

 Illustrate it by an example. 2. What is the difference between element- 

 ary and compound substances ? 3. What were the four elements accord- 

 ing to the ancients ? Show the error of this idea. 4. How many ele- 

 ments are there ? What is said of the possibility of some of them being 

 compounds? Name some of the most important elements. 5. Into what 

 two classes are the elements divided ? How many gases ? How many 

 liquids? How many metals? Name the best-known metals. 6. How do 

 the elements occur in nature ? Give examples. 7. What is said of the variety 

 of their combinations ? 8. What differences in form are noticed between 

 mineral and organized bodies ? 9. State in>full what is said of the influ- 

 ence of heat on the forms of substances. 10. Illustrate the fact that no 

 chemical changes accompany the changes of form just mentioned. 11. 

 Give examples of the nature of chemical changes. What is iron rust ? Do 

 gases unite with solid substances ? What are oxides ? 12. State in full 

 what is said of the extent and variety of chemical action. 13. What is 

 said of changes in the rocks ? 14. What of the sun's agency in chemical 

 changes? 15. Sum up the five characteristics of chemical change. 16. 

 What is meant by analysis and synthesis? 17. Contrast the old and 

 modern systems of nomenclature. Who introduced the present method ? 

 How are new compounds named? 18. On what principles are names of 

 compound bodies formed ? Give examples sulphur and sodium ? barium 

 and chlorine ? What do the terminations ous and tc signify ? 



