VOLTAISM. 



ever before heard of. It melted platinum with the greateft 

 facility. Trifhum, which had not been before melted, was 

 fufed into a globule. Charcoal was kept at a white heat in 

 chlorine gas and phofgene gas, without any change being 

 produced in the gas. It ignited fix feet of platina wire. It 

 was obferved, that when the wire was lefs than a certain 

 diameter, a lefs length was ignited. A view of one of the 

 before mentioned troughs is fhewn in^^. I. 



Since this plan is likely to become general, from its 

 great advantage both in economy and convenience, we (hall 

 venture to fuggeft fevcral improvements. 



For making all the variety of galvanic experiments, it has 

 always been a dtfideratum to have a battery, the furface of 

 which mav be increafed in any proportion, to a certain hmit, 

 without affecting the feries or number of combinations. 

 This has not hitherto appeared prafticable by any other 

 means than that of ufing diftinft batteries of different fizes. 

 A battery on the plan above dcfcribed, having loofe 

 plates, will admit of the advantage here alluded to, without 

 any other increafe of expence than that of the additional 

 plates which are meant to increafe the furface at pleafure. 



The cells in the earthen trough (hould be about an inch 

 and a half from one dividing furface to the other, and ca- 

 pable of receiving plates of four inches fquare. Each of 

 the cells may occafionally contain four plates, two of zinc 

 and two of copper. 



The form of the plates for this battery is reprefented in 

 fg. 2. Plali I. having a wire ftaplc, ab, of the fame metal 

 with the plate. The ftaplcs muft be made accurately of the 

 fame (ize for all the plates. A piece of wood, ah, [fg-i-) 's 

 made to pafs through all the ftaples of the plates. This 

 bearer, or fufpender, is divided into as many tranfvcrfe 

 grooves as there arc plates, of a depth capable of receiving 

 one-half of the diameter of the wire (laple. In the fame 

 bearer are alfo two longitudinal grooves, A A, B B, about 

 one-tenth of an inch wide and a quarter of an inch deep. 

 A number of Aiding pieces of brafs, a a, are introduced into 

 the latter grooves, equal to the number of combinations, 

 one half of the pieces being in one groove, and the other 

 half in the other. Thefe pieces of metal, after being placed 

 in proper fituations, are filed down with the tranfverfe 

 grooves, leaving the metal above the wood, where the ftaple 

 of a plate is iiilsnded to touch the metal, and filing the 

 metal away lower than the wood, where the ftaple is not 

 meant to be in contaft. 



Ai"ter the plates are arranged upon the bearer, alternately 

 copper and zinc, tlie pieces of fliding metal are made to 

 communicate with them, that the zinc plates of one cell 

 may communicate with the copper of the fucceeding cell, 

 the zinc of the laft with the copper of the next, and 

 fo on throughout the feries. The plates being all in their 

 places and properly conneftcd, a fecond piece of wood, c d, 

 {_fig-4-) is laid upon the bearer, witli coriefpondent grooves 

 to fit the ftaples. It is covered on the under fide with 

 woollen clotli, fo that when it is fcrewed to tiie bearer it 

 ferves to keep the plates fccure, and at the fame time pre- 

 ferves tlie connecting parts from the fumes of the acid 

 emptoyed in the battery. A feclion of the bearer, ftaples, 

 &c. are fecn in /ig. 4. The whole of the apparatus com- 

 plete is rcprcfeiitcd in Jig. 5, as drawn out of the cell. 

 Fig. 6. is an end view of the apparatus. 



In this battery, the maximum of furface ia when every 

 cell contains two plates each of zinc and copper. When 

 it is required to reduce the furface, nothing more is nccef- 

 fary than to take off the top part of the bearer, while the 

 plates arc rcfting in the trough, and then drawing out the 

 lower part. If the two end plates of each cell, one of 



copper and the other' of zinc, be taken away throughout 

 the whole, the bearer may be again introduced to its ori- 

 ginal fituation. The battery will now confift of the fame 

 ieries and half the furface. If a mean quantity of furface 

 be required, it is done by taking the end plates away from 

 a part of the cells. 



It appears, from an experiment detailed in Nicholfon's 

 Journal, vol. xxvi. p. 72, that the copper furface may be 

 increafed to advantage above that of the zinc. The experi- 

 ment is an follows : If an arc of copper and zinc be made 

 to conneft two glafs cups containing dilute muriatic acid, 

 the zinc part of the arc being in one cup and the copper in 

 the other, and if the connection be made between tlie two 

 cups, to compleat the circuit by an arc of copper wire, a 

 quantity of bubbles will be evolved from the copper wire of 

 the compound arc. If, however, inftead of the copper wire 

 the conneftion be made with a conical (lip of copper, a very 

 different effeft will be obferved, as the broad or pointed end 

 of the flip may be next to the zinc wire. When the broad 

 end is placed in the cup where the zinc wire is placed, a 

 much greater quantity of bubbles appears upon the copper 

 of the compound arc, than when the fmall end is placed 

 next to the zinc. Hence it would appear, that the copper 

 furface fhould be greater than that of the zinc. This may 

 be very eafily effefted, by dividing the copper furface into 

 fmall grooves, the fides of which make an angle of 60°, the 

 furface will by this means be doubled. This figure might 

 be given to the copper furface by means of a pair of fluted 

 rollers. It will be obvious, that if the grooves are not very 

 fmall, the different parts of the copper furface will not be 

 uniformly contiguous to the zinc furface, which is a matter 

 of fome importance. 



Having dcfcribed the mod convenient and economical 

 method of conftrufting a battery, we (hall now confider the 

 means of exerting the galvanic energy fo far as relates to the 

 interpofing fluid. 



In the galvanic battery, there appear to be two fources 

 from which the eleflricity is obtained. The one is that 

 which arifes from the contaft of the metals, and the other 

 from the chemical aftion between the interpofing fluid and 

 the zinc furface. The firft does not require even the 

 prefence of moifture, as is (hewn in the eleftric column of 

 De Luc. The fecond is rendered greatly confpicuous by 

 introducing between the oppofite furfaces any fubftance ca- 

 pable of oxydating and diiiolving the zinc. 



Acids, as appears from tlie preceding table, are the great- 

 eft promoters of the energy afforded by chemical atlion, be- 

 caufe they diflblve the zinc after it lias been oxydated by 

 the oxygen of the water. This is more efpecially the cafe 

 with the fulphuric and muriatic acids, bccaufe thefe acids 

 are not dccompofed by the zinc. The nitric acid produces 

 a ftill greater galvanic cffett, bccaufe the acid is dccompofed, 

 and oxydates the zinc with greater facility than water. The 

 \vater is alfo dccompofed when this acid is ufed. Zinc hy- 

 drogen is always evolved. 



The action is always increafed when the conduiTting 

 power of the fluid is increafed. Hence it would be proper 

 to life fome cheap faliiie folution with the acid, which will 

 not be decompofed by the fame. 



The faline folutions, alone, are very inferior to any of the 

 acids. But from what has been obferved, we may eafily 

 point out fuch falts as are beft fitted for the purpofc. All 

 the fuper-falts, from their cxccfs of acid, will anfwer this 

 purpofe ; or fuch falts as are decompofed by zinc. All 

 tliofe falts which aCt upon metals by forming triple falts, 

 fuch as muriate of ammonia and muriate of ioda, are Found 

 to aft very well in the galvanic battery. 



It 



