340 Experiments oh ih Chtmical PiroduSlkn aui Jgettey of EleStricity, 



I have fince found, that the fame apparatus will decompofe water, with a wire ^-^ of an 

 Inch diameter, coated in the manner before defcribed, if the fpark from the prime con- 

 duftor pafles to the diftance of ^% of an inch of air. 



Experiment 7. Ip. order to try how far the ftrength of the eleftrlc fpark might be re- 

 duced by proportional diminution of the extremity of the wire, I paflisd a folution of gold 

 in aqua regia through a capillary tube, and, by heating the tube, expelled the acid. There 

 remained a thin filin of gold, lining the inner furface of the tube, which, by melting the 

 tube, was converted into a very fine thread of gold, through the fubdance of the glafs. 



When the extremity of this thread was made the medium of communication through 

 water, I found that the mere current of ele£lricity would occafion a flream of very fmall 

 bubbles to rife from the extremity of the gold, although the wire, by which it communi- 

 cated with the pofitive or negative conductor, was placed in abfolute contact with them. 

 Hence it appears, that decompofition of water may take place by common eleftricity, as 

 well as by the eleftric pile, although no difcernible fparks are produced. 



The appearance of two currents of air may alfo be imitated, by occafjoning the eleflri- 

 clty to pafs by fio-e points of communication on both fides of the water ; but, in fa£t, the 

 refemblance is not complete; for, in every way in which I have tried it, 1 obferved that 

 ea»';h v«ire gave both oxigen and hidrogen gas, inflead of their being formed feparately, as- 

 by the ele6lric pile. 



I am inclined to attribute the difference in this rcfpeft to the greater intenfity with which 

 it is neceflary to employ common eledlricity ; for, that pofitive and negative cleftricity,, 

 fo excited, have each the fame chemical power as they are obferved to have in the cledric 

 pile, may be afcertained by other means. 



In the precipitation of copper by filver, an inftance of de-oxidation (or phlogifticatlon) 

 by negative eledlricity has been mentioned ; the oxidating power of pofitive ele£lricity 

 may be alfo proved, by its effedi on vegetable blue colours. 



Experiment 8. Having coloured a card with a (Irong infufion of litmus, I pafled a cur- 

 rent of eledtric fparks along it, by means of two fine gold points, touching it at the diftance 

 of an inch from each other. The efFed, as in other cafes, depending on the fmallnefs of 

 the quantity of water, was moft difcernible when the card was nearly dry. In this flate a 

 very few turns of the machine were fufficient to occafion a rednefs at the pofitive wire, very 

 manifefl: to the naked eye. The negative wire, being afterwards placed on the fame fpot, 

 foon reftorcd it to its original blue colour. 



By Mr. Volta's apparatus the fame effects are produced in a much lefs time. 



Befide the fimilarity which has thus been traced between the effects of elc£lrlcity excited 

 by the common machine, and thofe obferved from the ele£tric pile, I think it appears alfo 

 probable, that they originate from the fame fource. 



With regard to the latter, its power is now known to depend on oxidation ; fo alfo docs 

 the excitement in the former appear very much to depend on the fame procefs; for, 



2 Experimenl 



