CONTENTS. 



Part ;fF0urtfj. 



HISTOEICAL, THEORETICAL, AND PRACTICAL 

 CONSIDERATIONS. 



CHAPTER PAGE 



I. HISTOKICAL NOTES ...... 171 



II. THEORY . . ". >, v > :.,: * , ~ ; - ''. '.'* . 181 



III. PRACTICAL CONSIDEEATIONS . . *.;;, 196 



APPENDIX. 



LIST OF PRINCIPAL WORKS THAT HAVE CONTRIBUTED 

 TO OUR PRESENT KNOWLEDGE OP PHOSPHORESCENCE. 203 



