of Silver and of Copper, 393 



so as to form the springs, and after bending the two ends 

 together soldering them to a stiff back-piece, as shown ; care 

 must be taken that the spring front presses firmly on the back 

 before the two are soldered together. Several sets of clips 

 are fitted into one cross piece b, so that one frame may serve 

 for one or more cells, the double clips of any one set being 

 connected permanently to the single clip of the next set. 

 When the plates are being placed in the clips, the cross piece 

 which holds them is lifted off the frame and the plates placed 

 in position, the jaws of the clip being opened before the plate 

 is introduced. Care is also taken to open the jaws of the clip 

 before removing the plate, so as to obviate any risk of loss of 

 metal by friction between the holding-points and the plate. 

 This arrangement has been found very convenient for small 

 cells, as it allows the plates to be quickly and almost simulta- 

 neously placed in, and removed from, the liquid, and avoids 

 all risk of the plates touching each other or the sides of the 

 vessel ; but for cells to be used with currents of over 10 am- 

 peres the plates become rather too large, and the arrangement 

 shown in figs. 4 to 6 is then found more convenient. In this 

 form a frame of insulating material is fitted to the top of the 

 cell, and two sets of spring-contact clips, one set on each of 

 two opposite sides of the cell, are fixed to it. These clips 

 may be of the form just described, or they may be simply flat 

 strips of springy metal soldered to a stiff base piece, as in 

 fig. 5, in such a way that they press firmly against each other. 

 In the use of this form of cell the anode plates are placed in 

 contact with one set of clips and the cathode plates with the 

 other set, the number of anodes being always one greater than 

 the number of cathodes. The form of the plates and the mode 

 of placing them in the cells are illustrated in figs. 4 and 6, 

 from which it will be seen that the surface of the plate above 

 the liquid is made as small as possible by cutting away the 

 plate so as to leave two narrow strips connected to a cross 

 piece, c, d. The end c of the cross piece is held in the con- 

 tact clip, while the other end, d, is kept in position by a shallow 

 notch in the insulating rim. The insulating frame and 

 attached clips are simply laid on the top of the vessel, and 

 can therefore be lifted off and cleaned so as to insure perfect 

 insulation. 



Sizes of Plates and Densities of Solutions. — The size of the 

 plate can be varied within moderate limits in the case of 

 silver, and within very wide limits in the case of copper, 

 without greatly interfering with the quality of the deposit. 

 In the case of silver and silver nitrate the effect of making 

 the plate either too small or too large is, as has been pointed 



