VOLT A ISM. 



battery, are brought into feparate velTels containing any 

 fluid wliicli is a conduftor. If a wire of platina, in the 

 form of an arc, conneft the two glaffes together, that end 

 of the connefting arc in the pofitive glafs will afford hy- 

 drogen gas, while that in the negative glafs will furnifh 

 oxygen gas ; or, if we take all the four ends of the wires in 

 the circuit, the pofitive wire from the battery will give 

 oxygen, and that oppofite to it, in the fame glafs, hydrogen. 

 In the other glafs, the negative wire will afford hydrogen, 

 and the oppofite wire oxygen, fo that the water appears to 

 be decompofed in each glafs, fince oxygen and hydrogen 

 are furnifhed feparately by each glafs. If a number of 

 glalTes be arranged fimilarly, having connefting arcs of pla- 

 tina, and if the wires of the battery be introduced in the 

 extreme glafles, all the ends of the wires will alternately 

 furnifh oxygen and hydrogen. No theory yet brought for- 

 ward will fatisfaftorily account for thefe phenomena. Sir 

 Humphrey Davy would affert, that each of the wires from 

 the battery induced an oppofite ftate of eleflricity in the 

 wires oppofed to them ; and that in confequence the one 

 attrafted oxygen and the other hydrogen. Another theo- 

 rift might hold that the eleftricity, which enters the firft 

 glafs from the pofitive fide, decompofes the water, and com- 

 bining with the hydrogen, fets the oxygen free. The elec- 

 tricity and the hydrogen pals through the fluid to the op- 

 pofite wire, when the eleftricity deferts the hydrogen, and 

 paffing through the platina arc, decompofes the water in the 

 iecond glafs. The oxygen is again evolved, and the hy- 

 drogen carried to the next wire, and fo on through the re- 

 mainder of the glaffes. 



A very curious experiment of the above kind rather tends 

 to confirm the latter, than the former hypothefis. We, 

 however, give thefe fafts to the common ftosk, for the ad- 

 vantage of other labourers in this field of inquiry ; ftrongly 

 convinced that^very hypothefis yet advanced falls very fhort 

 of explaining all the phenomena of Galvanifm. 



Let the wires of a galvanic battery be made to terminate 

 ill a flat-bottomed veffel, containing pure water, about an 

 inch and a half from each other ; and if now another wire, 

 of an inch in length, be laid longitudinally between them, 

 but not to touch them, each end of the intermediate wire, 

 if of gold or platina, will afford gas. That end oppofite 

 the negative wire will give oxygen, and the other end of the 

 fame will furnifh hydrogen ; and if any number of bits of 

 wire be placed between the principal wires, at the fame time 

 they do not touch each other, o:.ygen and hydrogen will be 

 alternately furnifhed by the ends of the wires. When the 

 principal wires are brought nea-er together, and a platina 

 wire placed tranfverfely between them, one fide of the in- 

 termediate wire will furnifli oxygen, and the other hydro- 

 gen. This fatl is put in a more ftriking point of view, by 

 placing a plate of platina in a veffel of water edgeways, and 

 bringing the wires of the battery oppofite to each other, and 

 perpendicular to tiie fides of the plate. If the battery cm- 

 ployed confifl of 50 plates three inches fquare, a circular 

 fpot will be obferved on each fide the plate, oppofite the 

 wires. This appearance is caufed by the evolution of gas 

 from thofe parts of the plate only. 



It is fi:igular, that in all the experiments where* the con- 

 nefting wire was immerfed in the water, if any fubllance, 

 capable of increafing the condufting power of the water, 

 be very gradually added to it, the gafes given out by the 

 intermediate wire will diminifh, till they entirely ceafe to be 

 produced. The wire which was tranfverfely placed fooner 

 ceafcd to afford gas, than when it was in a longiU'dinal po- 

 fition ; and the cffeft fooner ceafed with the wire than with 

 Vol. XXXVII. 



the plate ; and in difil-rent plates, the continuance was a^ 

 the fize of the plate. 



If the plate, however, be cut fo as to divide the veffel 

 into two portions, and the edges fo completely cemented to 

 the fides of the veffel that no hquid communication exifts be- 

 tween the two portions, each fide of the plate will furnifh as 

 much gas as the wires, whatever may be the conducing 

 power of the iSuid. If the power, which induces the plate 

 or immerfed wires to give out gas, depended upon the in- 

 duAion of the oppofite wires, why is it not as great before 

 the fluid is divided as afterwards ? and why is it the fame 

 when pure water is ufed, whether the intermediate wire be 

 immerfed in the water, or is made to conned two portions 

 of water together ? Thefe are fafts which, in the prefent 

 flate of knowledge, do not admit of eafy folution. They, 

 however, fhew us the neceffity of having the cells of our 

 galvanic b.ntteries perfectly diftinft from each other. It 

 appecirs pretty clear, that that which conducts the oxygen 

 or the hydrogen, or perhaps both, paffes with greater faci- 

 lity through a good moifl conduftor than fhrough a metal. 



Decompoftion of Bodies in general The decompofition of 



water and of metallic oxyds was known to Cruickfhank, the 

 hiflory of whofc experiments we have already given ; and in 

 a very early flage of galvanic progrefs, it was obferved that 

 the alkali was feparated from muriate of foda in the gal- 

 vanic battery. In fubjeding muriate of foda to the galvanic 

 povvsr in a glafs tube, it has alfo been obferved that oxy- 

 muriatic acid was produced. The fubjeft of the decom- 

 pofition of falts, however, has been clearly made out, and 

 elbblifhed on true principles, by fir Humphrey Davy, 

 whofe experiments have been detailed under Galvanism. 

 The chemical agency of bodies, arifing from their relative 

 eleftric ftates, is no doubt the caufe of the decompofitions of 

 falts, and of all other bodies to a certain extent ; allhou"-h 

 there are many decompofitions, particularly the mctaJSc 

 oxyds and water, wkich are to be attributed to fome other 

 caufe much more aftive and expeditious. We fhall here 

 venture to draw a hne of diflindlion between the decompofi- 

 tion effefted by the eleftrical intenfity arifing from the con- 

 taft of the bodies, and that produced by the eleftricity, and 

 the hydrogen developed by the chemical agency of the 

 oxydable metal, and the oxydating fluid. 



If we take a fingle combination, for inftance, a zinc wire 

 connefted with a platina wire, the eleftrical intenfity arifing 

 from coiitaft is fo exceeding fm.ill, that it could hardly be 

 appreciated by the acid of the condenfcr. If this com- 

 bination be immerfed in water, no galvanic appearance takes 

 place, however near the immerfed ends be brought to each 

 other. If, however, we add to the water about one-tenth 

 its weight of muriatic acid, an immenfc quantity of hy- 

 drogen immediately appears upon the platina wire, and con- 

 tinues to be evolved fo long as the contaft is formed, till 

 the acid is expended. The cleftrical intenfity, however, is 

 the fame with the water as with the dilute .icid ; yet the 

 quantity of hydrogen upon the platina wire, when the .icid 

 was ufed, which can be attributed only to galvanifm of 

 chereiical aftion, is much more than could be obtained by 

 the moll powerful eleftric machine. It can readily be ad- 

 mitted, from experiments in which Dr. Wollallon decom- 

 pofed water by the eledlric machine, and from the clcftric 

 effefts of Deluc's column, that fomc water would be de- 

 compofed by the fingle combination, independently of the 

 chemical aftion ; but the difference is To glaring as to pro- 

 duce the flrongefl convic"lion, that the decompofition of 

 water and the tranfmiflion of hydrogen are not dependent on 

 the mere electric flates of the wirea. That the hydrogen is 

 3 O tranfiuiiied 



