104 THE ADVANCE OF SCIENCE 



other, have hitherto opposed to the recog- 

 nition of the presence and the condition 

 of matter. One eighteen-millionth of a 

 grain of sodium in the flame of a spirit- 

 lamp may be detected by this instrument ; 

 and, at the same time, it gives trust- 

 worthy indications of the material consti- 

 tution not only of the sun, but of the 

 farthest of those fixed stars and nebulae 

 which afford sufficient light to affect the 

 eye, or the photographic plate, of the in- 

 quirer. 

 Elec- The mathematical and experimental 



elucidation of the phenomena of electrici- 

 ty, and the study of the relations of this 

 form of energy with chemical and thermal 

 action, had made extensive progress be- 

 fore 1837. But the determination of the 

 influence of magnetism on light, the dis- 

 covery of diamagnetism, of the influence 

 of crystalline structure on magnetism, and 

 the completion of the mathematical theory 

 of electricity, all belong to the present 



tricity. 



