304 EXPERIMENTAL INVESTIGATIONS. 



1st. The purely mechanical effect of the voltaic current, 

 the oxide being forcibly detached without any farther chemical 

 combination. 



2nd. The neutral point when the current is arrested, the 

 intensity being too great for the usual action of solution, and 

 too feeble for the disintegrating action. 



3rd. The intense heat generated, which here, as in all 

 other voltaic experiments, appears to be proportionate to the 

 resistance. 



When, with a very powerful voltaic battery, small wire 

 electrodes of platinum are dipped into water acidulated with 

 sulphuric acid, a brilliant combustion, attended with a decrepi- 

 tating noise, is observed at the cathode, provided the anode 

 be sufficiently immersed in the liquid ; on inverting the 

 arrangement, i.e. immersing the cathode and touching the 

 surface with the anode, a slight spark only is perceptible ; in 

 both cases the heat is very intense, and the liquid boils at the 

 point of contact, giving off sulphurous acid fumes ; it would 

 seem, at first, that this phenomenon was contrary to the usual 

 fact observed in the voltaic combinations, viz. that the com- 

 bustion is more active at the positive than at the negative 

 terminal ; but I found it to be in reality no anomaly, as it is 

 the sulphur of the dilute acid which is principally concerned 

 in producing the brilliant effect at the cathode, and which, as 

 it is evolved, forms itself the positive terminal. When the 

 experiment was continued for some time a very dark choco- 

 late powder was deposited in the liquid, and was found to be 

 precipitated when ingredients of the utmost purity were em- 

 ployed. After various tests had been employed, this precipi- 

 tate was ultimately found to be soluble in nitro-muriatic acid ; 

 the solution, treated with ammonia, gave a double salt of 

 platinum, it also gave a precipitate with chloride of barium ; 

 the original deposit was, in short, sulphuret of platinum. The 

 gas evolved from the negative electrode in this experiment 

 was hydrogen, mixed with sulphuretted hydrogen. 



Entertaining a strong opinion that electricity is not a 

 specific fluid or fluids, but an affection of matter (possibly a 

 mode of motion) ; and, believing that all electrical phenomena 

 are intermolecular changes of the bodies, through which what 



