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.diameter, to a large brafs globe, fupported by the middle 

 jar at a proper height, io as to keep the infide communica- 

 lion properly arranged. A view of the figure will flicw 

 how the four are combined, fo aa to charge and dilcharge 

 all the ICO jars at once. 



Lieutenant colonel Haldane propofes the following me- 

 thod for meafiiring the force of an ekdtrical battery, during 

 the time of its being charged. 



Let the battery be inlulated, and at a fmall diftance from 

 it place an uninfulated eledtrical jar, and near the jar, one 

 cf Mr. Cuthbertfon's electrometers. The tledrometer being 

 a.djuft;ed according to the degree of force which is intended to 

 be employed as a meafure of force to be communicated to the 

 battery, conneiil the eleftromcter with the jar ; make a me- 

 tallic communication between the interior fide of the jar and 

 the exterior fide of the battery, and connedt the interior fide 

 of the battery with the conductor of an eltftrical machine : 

 then, by the operation of the eleftiical machine, the battery 

 receives a quantity of the eleftrical fluid, and becomes 

 charged. The fluid, which departs from the exterior fide 

 of the battery, is received by the elcclrical jar, which alfo 

 becomes charged ; but this jar, being connefted with the 

 eleftrometer, explodes as foon as it acquires a force fufhcicnt 

 to put the eleftrometer into motion. The quantity of the 

 elcftrical fluid which is received by this jar, between each 

 of the explofions, is a meafure of the quantity of the fluid 

 in the battery ; and the number of explofions or difcharges 

 of this jar fhews the number of meafures which the battery 

 contains, and conftqucutly the force which it is capable of 

 exerting when dilehargcd. 



For the author's demonftration of this method, and the 

 iUulVation of it by appropriate experiments, we mull refer 

 to Nichoifon's Journal, vol. i. p. 156, &c. 



Battery, Galvanic; the name ufually given to an ap- 

 paratus for accumulating the electricity which is produced 

 by the mutual agencies of certain metallic and carbonaceous 

 fubilances, and peculiar fluids. 



The firft inftrument of this kind was invented by the cele- 

 brated Volta of Pavia, in 1800, and various forms of it have 

 been fince adopted by different philofophers. 



The original battery, or the electrical pile, is compofed of 

 plates of zinc, plates of filver, and pieces of palleboard, of the 

 lize of the plates, raoillened in a lolution of fait in water : 

 and arranged in the order of zinc, filver, pafteboard, zinc, 

 filver, pafteboard, and fo on, till aferies fufficiently numerous 

 is formed. On account of the exp«nce of filver, copper has 

 been lately generallv fubllituted for it, with but little dimi- 

 nution of efleft ; and folutions ol muriate of ammoniac, of 

 nitrous acid, and of muriatic acid, have been employed in- 

 ftead of the folution of common fait, with very great advan- 

 tage as to the increale of the power of the combination. 

 In general any two metallic fubllances which are perfetl 

 conduftors of electricity, may be ufed, provided tTie inler- 

 pofed fluid is capable of oxidating at lead one of them. 



The powers ot galvanic batteries appear to be very much 

 connected with the chemical eiianges going on in them, and 

 hence plates of one metal may be made to fuppiy the place of 

 the two metals provided their different fides be expofed to 

 different chemically acling fluids, as has been (hewn by the 

 experiments of Mr. Davy. Thus copper, filver, and lead, all 

 form efficient combinations when they are arranged with two 

 different fets of pafteboard, one moiftened with diluted nitric 

 acid, and the other with folution of hydrofulphuiet of pot- 

 afti ; the order being metal, pafteboard moiftened with 

 acid, palleboard moiilened with hydrufulphuret, &c. In 

 fuch a cafe, if the batteiy is required to be of confiderable 

 psrmauency as to its cffciSis, it is necelTary to feparate the 



3 



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pafteboard moiftened in the chemical agents from each other 

 by a third fet of pafteboards, moiftened in common water. 



In inftances when piles are ereittd perpendicularly either 

 with two metals or with one metal, in confequtnce of the 

 oxidation andthelofs of moifture from prefTure and evapora- 

 tion, the eleftrical action ufually ceafes after a few days ; and 

 in order to renew it, afecond conltniction of theferies becomes 

 neceifary. Several methods have been propofed for mak- 

 ing iiiftruments m.ore permanent in their operation than 

 the pile, and more eafily rendered aftive ; but the moft in- 

 genious contrivance appears to be that of tl^e trough, dif- 

 covered by Mr. Cruickfhank. It confifts of a box of baked 

 wood, in which plates of copper and zinc, or of filver and 

 ^inc foldered together at their edges, are cemented in fuch 

 a manner as to leave a number of water-tight cells, cor- 

 relponding to tlie number of the fcries : the arrangement 

 becomes a6live when the cells are filled with the proper fa- 

 line fluids ; and it may at any time be eafily freed from oxide 

 by the ufe of muriatic acid. 



In the common apparatus of Volta, that part bounded by 

 the moft oxidablc metal, as, for inftance, the zinc, is found 

 in a pofitive ftate, with regard to eledlricity, and the other 

 part, as the copper, in a negative ftate ; and when a commu- 

 nication is made between the two ends, by means cf a con- 

 dudling body, a coiiftant circulation of elettricity is efta- 

 bliflied. 



The electricity of the galvanic battery is capable of being 

 partly transferred into the Leyden phial ; and its efFefts, as 

 has been fully Ihewn by the experiments of Mefirs. Nichol- 

 fon, Carhile, Woolafton, Van Marum, and Ritter, are fimilar 

 to thofe of common eleflricity, in a low ftate of inlenfity. 

 It gives ihocks to living animal organs, and excites muf- 

 cular contraftions in bodies for a confiderable time after 

 death. It affumes the form of fire in paCTmg from one 

 conduftiiig body to another in its highly concentrated ftate ; 

 and it ignites fmall metalhc wires or leaves, and caufes them 

 to enter into combuftion. It, fets fire to charcoal, fulphur, 

 alcohol, and other inflammable bodies ; and it rapidly decom- 

 pounds water and various other fluids. 



The intenfity of the eleftricity in galvanic batteries is 

 greater in proportion as the fcries compofing them are more 

 numerous : but the quantity of it depends upon the quantity 

 of furface they contain. Heuce equal numbers of large and 

 fmall plates arranged in different batteries produce nearly the 

 fame effefts on the human body which is an imperfect con- 

 duftor, and which can admit of the pafiage only of a certain 

 quantity of eleftricity of a low intenfity in a given time ; 

 but the large plates are in a determinate ratio, much more 

 powerful in igniting the metals, and in affecling ptrteft con- 

 diidtors through which a large quantity of electricity, in 

 any llate of intenfity, eafily and inllantly pafles. 



Many important philofophical difcoveries, which will be 

 fully defcribed in the article Gavanism, have been already 

 made, by meaus,of the galvanic apparatus, in different parts of 

 Europe; and a numberof eulightenedexperimenters have been 

 employed in invelligatingthe principles on which its operation 

 depends, . The theory of it is, however, as yet obfcure, aod 

 the perfeft developement of it will probably be connefled 

 with views more profound than any that have been as yet 

 obtained "of the- nature and agencies of eleftricity, and its 

 relations to chemical changes. See Phil. Tranf. for 1800 

 and 1801.. Nichoifon's Jcurual, vol.iv. and v., and vol. i. 

 new feries. Journ^ils of the Royal Inft. vol. i. Tilloch's 

 Phil. Mag. vol. x. xi. andxii. Annalen derphyfik. Jouraal • 

 de phyfique. Ar.nales de Chiiiie. 



BATTEURS ct'ejliadt; Icouts or horfemen, fentout be- ■ 

 fore, aad on the wings of an army, two or three mile.;, to 



ir.akc 



