CONTENTS ix 



CHAPTER XXI PAGB 



STUDY or THE ACTIVE PART or THE AIR - - 125 



CHAPTER XXII 

 ELEMENTS. COMPOUNDS. LAWS - 137 



CHAPTER XXIII 

 ACIDS - - - 142 



CHAPTER XXIV 

 ALKALIES - ...... 143 



CHAPTER XXV 

 HYDROGEN - 151 



CHAPTER XXVI 

 SALTS 159 



CHAPTER XXVII 

 CARBON AND SOME OF ITS COMPOUNDS 163 



ANSWERS 178 



INDEX - - - - 179 



