ON THE THEORY OF GALVANISM* 77 



the water and the ammoniac, and that the oxigen and azote 

 thus liberated, would unite together in fuch proportion as to 

 generate a folvent for the metal. We fuppofe the gas which 

 is difengaged from the pofitive wire to be produced by the de- 

 compoiition of the fluid in which it terminates, in confequence 

 of the lirong attraction which fubfifts between the electric 

 matter and hidrogen. It may reasonably be inferred that there 

 is a point of reciprocal faturation between thefe fubftances, or 

 that a given quantity of electricity cannot pafs between the 

 wires unlefs it be united to a definite quantity of hidrogen. If 

 the ele&ric matter in the pofitive wire exift there only in a 

 fmall quantity, it acquires for itfelf a fufficient proportion of hi- 

 drogen by decompoilng the ammoniac alone; but when the The folution of 

 apparatus is large and operates with energy, the ammoniac is aikali°decom- ** 

 inadequate to afford the neceffary fupply of hidrogen, and thepofed by a 



water becomes alfo decompofed. I endeavoured to fubmit the wcakcr P ow er, 



r • rs i n • r and alio water by 



truth ot this conjecture to the telt or experiment, tor which a ftronger. 



purpofe gold wires were employed terminating in ammoniac, Experiment, 

 and connected in different inftances with a greater or lefs num- 

 ber of metallic plates. The refults were upon the whole fa- 

 vourable, but on account of the minute quantities of gas pro- 

 cured, I was unable to afcertain its nature with as much ac- 

 curacy as was defirable. When the procefs went on rapidly 

 the water was decompofed as well as the ammoniac, and if it 

 was continued for a great length of time, the ammoniac at- 

 tracted carbonic acid gas from the atmofphere, and thus pro- 

 duced a fource of error in the refults. Several other metallic 

 bodies which were interpofed between the ends of the pile, 

 were ail of them more or lefs corroded in confequence of their 

 ftrong attraction for oxigen. When copper and tin were 

 ufed, the oxides were dillblved by the ammoniac; in the for- 

 mer cafe this was rendered vifible by the blue colour which the 

 liquor affumed, and in the latter by the precipitation of the 

 oxide of tin effected by the addition of fulphuric acid. The 

 flips of tin foil which were employed had their extremities 

 changed to a brown colour, particularly that which was con- 

 nected with the negative end of the apparatus. 



After thefe obfervations upon the action of the pofitive wire, The minus wire 

 there remains little to be added on the fubjefl of the oppofite of the P iIe * 

 one; it merely receives the electric fluid after its paffage 



through 



