144 R< marks on the Galvanic BaW ry. 



The resistance of the element was determined for each 

 cell separately. Then the cells were placed one inside of 

 the other and the total resistance determined as before. 

 After which it was found for two at a time. These several 

 determinations gave us a series of equations, involving 

 the resistance of each separate cell together with the 

 specific resistance of the liquids. 



The following are the results expressed in an arbitrary 



unit: 



No. 1, Resistance, -2 



No. 2, " 17 



No. 3, " 7 . 



Specific resistance of the liquids s. c. saturated solution, 

 s, :. 25° B. 13. From which it appears that the specific 

 resistance of the liquids is about the same as for a white 

 clay cell of the ordinary size. 



As q. is increased by lessening the interval resistance 

 other things being equal, it is apparent that the leather 

 cells are superior to those made of white clay. 



On the construction of DanielVs Battery. — For a local bat- 

 tery, where the external resistance is small, two-gallon 

 stone jars may be used for the vessel holding the s. c. 

 solution. The negative plate is best made of sheet lead 

 instead of copper as heretofore ; as it is less expensive and 

 is easier bent in the proper form. It is desirable to per- 

 forate the sheet with an ordinary punch, in order to secure 

 a more free circulation of the liquid surrounding it. 

 Ordinary sheet tin makes the cheapest negative plate, but 

 it is unfit for general use, where the battery is required to 

 be kept in constant action for a long period. For if the 

 s. c. solution is not kept saturated, chemical action takes 

 place between the iron and tin which soon dissolves the 

 plates. I have, however, used it successfully. If the 

 solution is kepi saturated, in a month or so the sheet will 

 be covered with a fine plate of copper, which may be easily 



