Relation by Measure of Common and Voltaic Electricity, 36 1 



might be considered as indicating a constant voltaic current, 

 which in eight beats of my watch (369.) could supply as much 

 electricity as the electrical battery charged by thirty turns of 

 the machine. 



373. The following arrangements and results are selected 

 from many that were made and obtained relative to chemical 

 action. A platina wire one twelfth of an inch in diameter, 

 weighing two hundred and sixty grains, had the extremity 

 rendered plane, so as to offer a definite surface equal to a cir- 

 cle of the same diameter as the wire ; it was then connected 

 in turn with the conductor of the machine, or with the voltaic 

 apparatus (369.), so as always to form the positive pole, and 

 at the same time retain a perpendicular position, that it might 

 rest, with its whole weight, upon the test paper to be em- 

 ployed. The test paper itself was supported upon a platina 

 spatula, connected either with the discharging train (292.), or 

 with the negative wire of the voltaic apparatus, and it con- 

 sisted of four thicknesses, moistened at all times to an equal 

 degree in a standard solution of hydriodate of potassa (316.). 



374. When the platina wire was connected with the prime 

 conductor of the machine, and the spatula with the discharging 

 train, ten turns of the machine had such decomposing power 

 as to produce a pale round spot of iodine of the diameter of 

 the wire: twenty turns made a much darker mark, and thirty 

 turns made a dark brown spot penetrating to the second thick- 

 ness of the paper. The difference in effect produced by two or 

 three turns, more or less, could be distinguished with facility. 



375. The wire and spatula were then connected with the 

 voltaic apparatus (369.), the galvanometer being also included 

 in the arrangement; and a stronger acid having been pre- 

 pared, consisting of nitric acid and water, the voltaic apparatus 

 was immersed so far as to give a permanent deflection of the 

 needle to the 5^ division (372.), the fourfold moistened paper 

 intervening as before*. Then by shifting the end of the wire 

 from place to place upon the test paper, the effect of the cur- 

 rent for five, six, seven, or any number of the beats of the 

 watch (369.) was observed, and compared with that of the 

 machine. After alternating and repeating the experiments of 

 comparison many times, it was constantly found that this 

 standard current of voltaic electricity, continued for eight beats 

 of the watch, was equal, in chemical effect, to thirty turns of 

 the machine; twenty-eight revolutions of the machine were 

 sensibly too few. 



376. Hence it results that both in magnetic deflection (371.) 



* Of course the heightened power of the voltaic battery was necessary 

 to compensate for the bad conductor now interposed. 



Third Series. Vol. 3. No. 17. Nov. 1833. 3 A 



