Sir Humphry Davy 113 



some respects more than the foundation of our present 

 science of electro-chemistry. The sensation which the paper 

 created in England was great; its effect abroad may be 

 judged from the fact that the French Academy recommended 

 Davy as first recipient of the gold medal, promised by 

 Napoleon for " the best experiment that should be made 

 in each year on the galvanic fluid." This recognition had a 

 special value, owing to its being bestowed in the face of a 

 bitter political hostility between France and England, then 

 at war with each other. 



Davy continued his researches and in the following year 

 was already able to announce another discovery of funda- 

 mental importance which forms the subject of his second 

 Bakerian lecture. The construction of electric batteries had 

 been materially improved by Cruikshank, a surgeon, and 

 Davy had modelled his own apparatus on Cruikshank's 

 pattern. The metals used were copper and zinc, and two 

 of the batteries consisted of 50 and 100 cells respectively, 

 the plates in the first measuring six, and in the second, 

 four square inches. With the two batteries in series, Davy 

 made a determined attempt to decompose the so-called 

 fixed alkalis : soda and potash. When a current is passed 

 through the aqueous solution of these bodies, only hydrogen 

 and oxygen are set free at the poles. Other experimental 

 methods had, therefore, to be tried. As potash at ordinary 

 temperatures does not conduct the current sufficiently well 

 to show any effect, it was raised to a temperature at which 

 it fused, and the current then produced a highly inflammable 

 substance, which burst into flame by contact with air. In 

 order to isolate that substance, Davy saw that it was 

 necessary to conduct the experiment at ordinary tempera- 

 tures, and succeeded in doing so by utilizing the hygroscopic 

 properties of the substance, which, on exposure to damp 

 air, cause it to become covered with moisture. The current 

 then passed through the highly-concentrated liquid surface 

 layer. With his 150 cells Davy found the electrical effect he 

 looked for, and was able to isolate metallic potassium. He 

 announced his discovery in these words : 



" Under these circumstances a vivid action was soon 



observed to take place. The potash began to fuse at 



H 



