BUNSEN'S ELEMENTS. 663 



.connection between two cells, and E shows a complete battery of 

 four cells, as seen from above. In clamping the platinum the metal 

 is placed between the plate of ebonite and the smooth inner side of 

 the binding screw, 'so that the pressure screw works against the 

 opposite side of the ebonite plate, not against the platinum, which 

 would be spoiled by it ; again, when a strip of copper is to be 

 connected with the platinum, the latter is first placed upon the 

 ebonite, then the copper upon the platinum, and the clamp is set 

 with its flat inner side against the ebonite, while the screw works 

 against the copper ; finally, for connecting with the zinc, the copper 

 is placed upon the outside of the projecting zinc. These various 

 directions will become quite clear if diagrams B and in figure 339 

 are attentively studied. 



Fig. 340 shows a Bunsen's cell with the terminal screws, which 

 are provided with nuts, by means of which the connecting wires 

 may be clamped to the binding screws. 



FIG. 340 (an. proj. ; ^ real size). 



The carbon forms a rectangular four- sided prism ; its terminal 

 binding screw consists of a piece of brass, a, bent twice at right 

 angles, and of a small rectangular plate, 6, which has the spindle of 

 a screw, s, attached to it. The spindle passes loosely through a hole 

 in a, and carries the nut m, which can be turned by a milled edge. 

 To clamp this binding screw, the nut m is loosened until the plate 6 



