118 ANALYSIS OF THE GALVANIC PILE. 



Apparatus der glass rods, covered with insulating varnish, and the assem- 

 s e blage of groups contained in each frame rests at the bottom 



on small insulating pillars. The space within the glass 

 rods (except a small part of it at the bottom, in which a 

 section of plates is represented) is, in the figure, indicated 

 by only a dotted line; because it varies in height, in the 

 course of the experiments, according to the number of the 

 groups and their arrangement. The order of succession in 

 the associated plates of the different metals being inverse in 

 the opposite columns, these are connected together at their 

 Tower ;jarts by a brass slip d y whicn becomes the middle 

 point of the pile, and its extremities are tuns transported to 

 the tops of the columns. 



The upper part of each frame is constructed in the usual 

 manner; the three glass rods passing through a piece of 

 wood, where they are wedged, in order to give to a screw, 

 which passes through the piece of wood, the power to press 

 on the groups at the different heights which they attain, in 

 different stages of the experiments. With each column is 

 connected a gold-deaf electroscope, movable upon a wooden 

 rod: from its top projects a brass spring, which presses on 

 the top of the column, in order to secure a real contact. 

 When the gold leaves diverge, and it is wanted to know 

 whether the divergence is positive or negative, the electro- 

 scope is lifted up only so far as to separate it from the pile, 

 and is then tried in the usual manner. 



With respect to chemical effects in the circuit, I shall 

 confine myself to those which were first observed in glass 

 tubes filled with water, at the opposite extremities of which 

 enter wires, the latter serving to connect the water with 

 the extremities of the pile. I made these experiments with 

 different kinds of wire, but in the main course of them I 

 used brass wires: hus, while inflammable air proceeded 

 from one of them, calcination took place on the other: these 

 are the only effects which will be considered in the follow- 

 ing experiments. For a purp s which I shall explain, I 

 placed two of these tubes in the circuit, connected together 

 in their lower parts by a brass ring, as may be seen at c, 



fig:- i. 



|n the description of the experiments, the chemical ef- 

 fects 



