82 The Rev. Dr. Callan's Experiments on the 



that of four cells in series ; because if a battery of 100 cells be 

 arranged in scries^, a single bad porous cell or bad zinc plate 

 will diminish considerably the power of the entire battery ; but 

 if the 100 cells be arranged in twenty-five rows, each con- 

 taining four cells, and all the terminal zinc plates be connected 

 so as to act as one plate, and all the end iron cells be connected 

 so as to act as one, a bad porous cell or zinc plate will diminish 

 the power only of the row to which it belongs, but not of the 

 other rows. 



Some of my experiments led me to believe, that, by means of 

 the arrangement of the electrodes for a current of high intensity, 

 the decomposing power of the battery may be considerably in- 

 creased; from other experiments I was somewhat disposed to 

 infer that by such ai'rangement no increase of power can be 

 gained. I am at present in doubt, and must remain so till the 

 state of my health enables me to repeat my experiments. 



The fluid which I first used in the voltameter was a solution 

 of caustic potash. When a current was sent throiigh the solu- 

 tion, the iron vessel was soon filled with foam, which came out 

 through the jet with the mixed gas and extinguished the flame. 

 I then tried a solution of carbonate of soda. The soda prevented 

 the oxidation of the positive electrode as well as potash, and did 

 not foam so much. However, even with soda, the quantity of 

 foam was so great, that the iron voltameter, 16 inches high and 

 6 inches in diameter, would be very soon filled with it if a bat- 

 tery of more than about twelve 6-inch cells were employed. 1 

 tried various means of preventing the foam. I first covered the 

 electrodes all round with a cloth, so that the gases should pass 

 through it. Many of the bubbles were thus broken ; but when 

 a powerful battery was used, the voltameter was soon filled with 

 foam. I then put about a teaspoonful of coal naphtha into the 

 vessel. This prevented the foam from rising to any considerable 

 height in the vessel, but it was somewhat injurious to the light. 

 I also tried turpentine : it diminished the foam, but injured the 

 light more than the naphtha. I think it increased the vio- 

 lence of the explosion of the gases. I afterwards tried some 

 nitre, and also common salt ; each of them pi'evented the foam, 

 but destroyed the light. After failing in all my efforts to prevent 

 the foam, I thought there was no alternative but to get an iron 

 vessel 80 large that all the foan\ which could be produced by a 

 powerful battery would Ije contained between the top of the elec- 

 trodes or surface of the fluid, and the top of the vessel without 

 rushing through the jet. Latterly, I have tried carbonate of am- 

 monia instead of sodftj and have found that it foams much less, 

 and that it prevents the action of the oxygen on the positive elec- 

 trode. A solution of the proper strength will be obtained by 

 dissolving an ounce and a quarter, or an ounce of the carbonate 



