76 



ON THE THEORY OP GALVANISM. 



farily cither proceed from the wire itfelf, or be difengaged 

 from the fluid in which the wire terminates. If it proceed 

 from the wire itfelf, we may conclude that in whatever fluid 

 the wire is plunged, the oxigen will ftill be emitted, except the 

 fluid fliould itfelf polfefs an attraction for oxigen. Upon the 

 other fuppofition, however, that the oxigen proceeds from the 

 decompofition of the fluid, in confequence of the electricity 

 uniting itfelf to hidrogen in its palTage between the wires, we 

 may expect to be able to fufpend the production of oxigen, by 

 prefenting to the wire a liquid which contains hidrogen united 

 Immcrfedin am- to fome other element. The liquid cauftic ammoniac promifes 

 moma. to an f wera u the re q U jfite purpofes, and we (hall find that the 



experiments made upon it by Mr, Cruickfhank and Mr. Davy, 

 though not precifely fimilar in their refults, afford conclufions 

 not unfavourable to our hypothefis. Mr. Cruickfhank em- 

 ployed wires of platina, and when thefe were connected with 

 the pile, and permitted to terminate in ammoniac, he found 

 Azote and hidro- that the gafes evolved were azote and hidrogen, with fo fmall a 



gen evolved by mixture f ox } gen as to render it probable that this latter fub- 



plat na wires in ° * 



ammonia. fiance proceeded rather from fome accidental circumfrance, 



than from the effential nature of the operation. Mr. Davy 

 Gold wires j ufed gold wires which terminated in two glafles of ammoniac, 

 connected to each other by means of mufcular fibres. He 

 found that the pofitive wire evolved gas only in fmall quantity, 

 and that it was a mixture of three parts of oxigen and two of 

 azote, while the other wire gave out hidrogen in confiderable 

 corrofion; quantity ; the pofitive wire was vifibly corroded. I was for 



fome time at a lofs to reconcile the refults of thefe able experi- 

 menters, but upon reflection I was led to conclude that the va- 

 riation might be produced in part from the nature of the wires 

 which they ufed, and partly from a difference in the energy of 

 their refpeclive piles. In order that the experiment fliould be 

 unexceptionable, it is neceffary that a metallic conductor be em- 

 ployed which pofleffes little attraction for any of the elements 

 conipofing the fluid in which it terminates ; as by this precau- 

 tion any change of compofition which takes place muft depend 

 altogether upon the affinities of the electric fluid. Gold is on 

 this account lefs proper than platina. It may be conjectured 

 that in Mr. Davy's experiment with gold wires, the predif- 

 pofing affinity of the oxide of this metal for an oxigenated ni- 

 tric acid, would caufe the decompofition of a portion both of 



the 



