Intelligence and Miscellaneous Articles. 547 



glass bell into the interior of the porous cylinder, where it terminated 

 in a plate of platinum or copper. Outside the porous cylinder 

 another plate of platinum was placed, and connected with the posi- 

 tive pole of the battery. The whole stood in a large glass vessel, 

 which, as well as the interior porous cylinder, was filled with water. 

 The intensity of the current was measured by a galvanometer. As 

 soon as the circuit was closed, the liquid rose in the porous cylinder, 

 and flowed out from the horizontal tube into a weighed vessel. The 

 results obtained by means of this apparatus were as follows : — 



1 . The quantity of fluid which flows out in equal times is directly 

 proportional to the intensity of the current. 



2. Under otherwise equal conditions, the quantities of fluid flowing 

 out are independent of the magnitude of the conducting porous 

 surface. 



To avoid any uncertainty arising from the laws of the flow of 

 liquids through small orifices, Wiedemann measured the intensity of 

 the mechanical action of the current by determining the height of a 

 column of mercury which would hold the transferring force in equi- 

 librium. For this purpose a graduated tube or manometer filled 

 with mercury was attached to the extremity of the horizontal tube 

 above mentioned. With different currents and porous surfaces of 

 different extent, the mercury in the manometer rose to different 

 heights. By the measurements of these heights, the following results 

 were obtained : — 



3. The height to which a galvanic current causes a fluid to rise is 

 directly proportional to the intensity of the current, and inversely 

 proportional to the extent of the free porous surface. 



The mechanical action of a galvanic current may aL-o be referred 

 to its simplest principles by the following proposition : — 



4. The force with which an electric tension, present upon both 

 sides of a section of any given fluid, urges the fluid from the positive 

 to the negative side, is equivalent to a hydrostatic pressure which is 

 directly proportional to that tension. 



In this manner therefore we obtain a simple measure of electric 

 tension and its mechanical action in terms of atmospheric pressure, 

 and consequently of gravity. 



The above laws hold good only for fluids of the same nature. 

 When diff"erent fluids are subjected to the action of the currents, the 

 mechanical action is greatest upon those which oppose the greatest 

 resistance to its passage. The requisite data are still wanting to 

 determine the precise connexion between the mechanical action and 

 the resistance ; but observations made with solutions of sulphate of 

 copper of different degrees of concentration, appear to shew that the 

 quantities of fluid transferred in equal times by currents of equal in- 

 tensity are nearly projjortional to the squares of the resistances. — 

 Silliman's Journal for November 18.52, p. 42(). 



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