of Substances upon Voltaic Action. 443 



mission during 37 days; and a total of 631 trustworthy observa- 

 tions of the galvanometer was taken, the number per day 

 varying from 3 to 20. The ends of the tubes presented to the 

 cube were reversed a total of 47 times, and the periods of 

 time between the reversals varied from 2 to 52 hours. The total 

 average magnitude of deflexion of the galvanometer needles 

 whilst one end of the tubes was presented to the cube was 

 greater than that of the other, and the proximity of the lead 

 slightly increased the voltaic current when one set of elec- 

 trodes was near the cube and slightly decreased it when the 

 other set was near. 



The correct interpretation 1 consider of these results is, 

 that whilst nearly the whole of the deflexion of the needles in 

 each case was due to a minute voltaic current produced by 

 inequality of chemical action upon the two sets of electrodes 

 and by motion of the tubes, the proximity of the lead to the 

 ends of the tubes tended to increase the positive or decrease 

 the negative electromotive force. (This conclusion was sub- 

 sequently confirmed by results obtained with other appa- 

 ratus.) The results appear to indicate a loss of energy of 

 the mutually approaching masses of zinc and lead, attended 

 by an extremely minute alteration of the molecular conditions 

 of the two substances. 



The chief defects of this form of apparatus were : — 1st, the 

 large mass of lead required ; 2nd, too great distance of the 

 lead from the electrodes ; 3rd, the narrowness and considerable 

 length of the glass tubes causing too much electric conduction- 

 resistance ; and, 4th, the irregular differences of temperature 

 attending the use of so large an apparatus ; I therefore 

 designed another arrangement. 



Apparatus No. 2. 



This apparatus was essentially the same in principle as the 

 first one ; it was, however, very much smaller, being about 

 18 inches long, 7 inches wide, and 6 inches high. It con- 

 Fig. 1. 



n 



DE HO 



sisted of 24 J_-shaped glass tubes, each 5£ inches long and 

 about -fe inch diameter (see figs. 1 and 2), fitted with zinc 



