IN A CLOSED GALVANIC CURCUIT. 239 



time ascending the tube d, have no essential influence on the 

 ultimate result. By using copper instead of platinum plates, 

 and a solution of sulphate of copper instead of water, this dis- 

 turbing influence of course entirely disappears. 



If a galvanic current of constant intensity be conducted 

 through a new apparatus for some time, it is observed that the 

 quantities of water issuing from the tube e, in equal times gra- 

 dually increase a little, especially if the surface of the clay 

 cylinder be but a small one. At the same time the water in the 

 cyUnder becomes cloudy. The cause of both of these phaenomena 

 is, that the water streaming forcibly through the pores of the 

 clay cylinder carries particles of clay along with it (as Becquerel 

 has already observed). The capillary apertures of the cylinder 

 become thus widened and offer less frictional resistance to the 

 water passing through them. Consequently, after longer use 

 of the same apparatus more constant results can be obtained 

 than at first. As before mentioned, the same effect is obtained 

 by boiling the clay cylinder for some time in hydrochloric acid. 



Lastly, the results of the first two or three observations made 

 with a new apparatus are in general too small, because the 

 atmospheric air present in the pores of the cylinder requires 

 first to be displaced by the water moved by the galvanic 

 current. 



§4. 



The object of the first experiments made with the above- 

 described apparatus was, to investigate whether currents of 

 different intensity forced different quantities of liquid through 

 the clay cylinder, and if so, whether any simple relation existed 

 between these quantities and the corresponding intensities. 



The galvanic battery employed in these experiments con- 

 sisted of DanielPs elements. A tangent compass was used to 

 measure the intensities, or if the current was weak, a galvano- 

 meter was employed, which had previously been compared with 

 the tangent compass, and whose needles deviated somewhat 

 from the astatic position. 



After proving by many experiments, that by repeated employ- 

 ment of the same current equal quantities of liquid were always 

 pushed into the clay cylinder in equal times, and thus made to 

 issue from the tube e into the vessel z, currents of different 



