HISTORY OF GALVANISM. 83 



this instrument into three parts. He divides it Dissection 

 into three separate groups, corresponding to what 

 he regards as the three elements of the pile. These 

 elements are the two metals and a fluid. They 

 were first placed with the fluid between the two 

 metals ; then with the fluid in contact with one, PLATE n. 

 and afterwards in contact with the other metal, the 3^4'. ' ' 

 different groups being kept distinct from each other 

 by small wire stands, so as to confine the action to 

 that part alone. When the piles were fitted up in 

 these three different ways, a delicate electrometer 

 was attached to each extremity, and they were also PLATE n. 

 connected by the interrupted wire passing through Fl ' 12 * 

 water. His first set of experiments were made 

 upon the pile in which the groups were arranged First dis- 

 with the fluid between the two metals. By means JJe'jJne?* 

 of the electrometer, he observed which ends of the 

 apparatus were in the positive and negative states 

 respectively ; and he likewise made some new ob- 

 servations on the direction which the electric cur- 

 rent takes in its passage across the water in the 

 interrupted circuit and in the body of the pile 

 itself. His observations agreed with those origin- Observa- 

 ally made by Nicholson, that the extremity of the direction e 

 pile, which is connected with the wire emitting ent he an!T 

 oxygen, is positive, and that the current is directed . n . the P" 

 from this to the wire which emits the hydrogen, negative 

 He informs us, however, that although electrome- 

 ters placed at the extremities, when they are af- 

 fected, indicate the electricity to be in the state , 

 mentioned abov ; yet they are not always both of 



