MODERN CHEMISTRY. 461 



in kind. The simplicity of the method in nowise lessens the 

 value of the results obtained. Mr. Graham has already 

 drawn from this enquiry some important distinctions as to the 

 physical properties of the substances acted upon, and as to 

 the part which the water itself bears in this phenomena. It 

 is a new path to knowledge, but certain hereafter to coalesce 

 with the many others which have the same object before 

 them. 



If this were a treatise on Chemistry, instead of a mere 

 outline of the present progress and objects of the science, it 

 could not be concluded without an ample review of those 

 great discoveries of the last fifty years, which depend upon 

 and illustrate the relations of Electricity and Light to 

 Chemical action. The subject, however (already touched 

 upon in some preceding articles), is far too large for our 

 limits here ; and we can notice it only so far as to show the 

 important place it holds as a part of physical science. 



The decomposition of water by voltaic electricity, with 

 disengagement of oxygen and hydrogen at the opposite poles, 

 was the great initial fact which associated chemical and elec- 

 trical phenomena. Further experiments extended this law 

 of decomposition to other compound bodies, placed in solu- 

 tion in the electric circuit; certain of their compound 

 parts always appearing at the positive pole, others at the 

 negative. The admirable researches of Davy, in 1806-7, 

 enlarged the scope of these results, by showing that chemical 

 agents under this condition of electric polarity were seem- 

 ingly transported freely and unaltered from one pole to the 

 other; though made to pass through intermediate vessels, 

 containing chemical agents with which in ordinary circum- 

 stances they would instantly and forcibly combine. In 

 sequel to these experiments, and by the same agency, Davy 

 succeeded in obtaining the metallic bases of the alkalies and 



