GROVE'S BATTERY.] 



UNDULATORY FORCES. ELECTRICITY. 



18& 



Fig. 41. 



The accidental occurrence of this is common, and is the 

 cldef objection to the use of the arrangement. 



GROVE'S BATTERY. The next arrangement to which 

 we have to direct attention, is that invented by Pro- 

 fessor Grove ; which is always employed at the present 

 time for lecture-table purposes, because it is the most 

 powerful of all arrangements yet discovered. The same 

 principles are involved in its construction as in that of 

 Daniell's ; but the hydrogen is removed by means of 

 strong nitric acid ; and platina, instead of copper, is 

 employed. There is a great advantage in the use of 

 platiua, because it is quite unacted on ; and the further 

 the affinity of the two metals 

 forming a battery, are apart, 

 the greater is the power of the 

 combination. 



The annexed engraving 

 illustrates a flat cell of a 

 Grove's battery; in which a 

 represents the outer porcelain 

 pot ; z z a plate of zinc, bent 

 so as to fit into the pot, and 

 rise up on each side ; 6 b is a 

 porous pot ; and p a platina 

 plate ; w w are wires from 

 each plate. The outer pot 

 next the zinc is charged with 

 sulphuric acid and water ; and 

 the porous pot with strong 

 nitric acid. A powerfid current of electricity is thus 

 generated, which lasts so long as any nitric acid re- 

 iH. Fumes of nitrons acid are given off ; and this is 

 a, serious objection to the battery; for they destroy 

 .thing they come in contact with, making it neces- 

 sary to place the instrument in some position where a 

 strong draught can be obtained. 



The flat cell is the usual form of arranging the bat- 

 tery ; but circular pots may be used : the power, how- 

 ever, is decreased, owing to the increased distance of 

 the metals. A series of flat cell* four inches deep, 

 three broad by two wide, with the usual-sized porous 

 culls, will keep in action for about an hour to an hour 

 and a-half. Great care must be taken that the zinc 

 is well amalgamated before use, as the nitric acid soon 

 attacks it. 



We frequently employ a strong solution of chloride of 

 zinc, in place of sulphuric acid and water. It dispenses 

 with the necessity of amalgamation, and never requires 

 renewal, except in the addition of more water. It is 

 readily prepared by adding common zinc to hydrochloric 

 acid and water ; and many conveniences attend its em- 

 ployment. 



The chief expense of this battery is the platina ; but 

 for the benefit of those who are desirous of a powerful ar- 

 rangement, at a cost of nbt more than twenty shillings 

 by which they may perform all the experiments which will 

 be introduced in our future pages we shall give 

 minute directions which will enable our readers to con- 

 struct one for themselves. 



Procure twenty gallipots, two inches high, and as 

 many bowls of largo tobacco-pipes. The latter must 

 Fig. . have the small hole at the lower end 



stopped up by means of planter of 

 Paris, and a kind of stand made of 

 the same material, to support the 

 bowls upright, as seen in Fig. 42. 

 It is as well to keep a few of these 

 simple porous pots ready, in case 

 of accident to those in use in the 

 battery. Have cut, by a tin-smith, 

 twenty pieces of zinc, six inches long 

 and two inches deep. (See Fig. 43). 

 The long thin strip mav pither be 

 [ cut from the shc/-t, "i I t .1 piece of 

 copper soldered on the zinc ; it should 

 be four inches long and half an inch wide. (1.) The 

 sheet must be then bent into the form of a cylinder (2), 

 and the copper or zinc strip U so bent as to form a 



The zinc, when bent into form No. 3, must be amal- 

 gamated. 



Fig. 43. 



There must be soldered on to each of nineteen of the 

 zincs, a piece of platina, a quarter of an inch wide and 

 two inches long. This is easily done by wetting the end 

 of the copper strip with a little muriatic acid, and then 

 dipping it into a little soft solder melted in a ladle. Some 

 of the solder will adhere to the copper ; and by now holding 

 it in the flame of the spirit-lamp, and placing the edge of 

 the platina with it in the flame, the tin Fig. . 

 will melt and the platiua will adhere, and 

 must be allowed to cool. The whole, when 

 finished, will appear as in Fig. 44. 



By this easy plan, all the connections 

 are complete without binding-screws. To 

 one zinc, and to one platina (the first and 

 twentieth of the series), a copper wire of No. 16 gauge, 

 and thirty inches long, must be soldered. These will 

 form the last plates of the series, from each of which 

 the wires will serve to conduct the electricity. 



The next step is to put the battery together. First, 

 fill each of the tobacco-bowls with strong nitric acid, 

 and place them in the centre of each gallipot. Take 

 care not to spill the acid over into the outer pot, as that 

 would speedily destroy the zincs. Then place the zinc 

 cylinder, to which the wire is attached, in the first pot; 

 and, in the second, put another cylinder of zinc, with 

 its platina immersed in the tobacco-pipe bowl of the 

 first one, the platina of the third zinc in the bowl of 

 the second pot, and so on throughout the series. 



Having thus arranged that the platiua of each zinc 

 shall dip into the bowl of the pot immediately preceding 

 it, on arriving at the last pot, the platina, with the 

 wire attached, must be placed in its bowl, and the wires 

 kept steady by driving into a board two nails, round 

 which each of them should be twisted, but kept separate. 



The outside pots, containing the zincs, should each 

 now be filled with sulphuric acid and water, in the pro- 

 portion of one of the former to eight of the latter by 

 measure. The mixture should be cooled before being 

 poured into the cells. 



A battery of this description will melt ten inches of 

 thin iron wire ; will give a spark of an eighth of an inch 

 long between charcoal points ; decompose water rapidly, 

 potass, soda, <trc. ; and, in short, will answer every pur- 

 pose which the student can require it for. We have 

 frequently used such an arrangement for purposes of 

 research, extending 1 the number of cells to one hundred, 

 from which some interesting results may be obtained. 



Several modifications of Mr. Grove's battery have 

 been proposed, the object having been to do away with 

 the platina. Considerable misunderstanding seems to 

 rest on this point. The first cost of platina is its only 

 cost ; and if it be carefully dealt with, and frequently 

 heated red-hot, it will last almost any length of time. 

 We may here observe, that we invariably heat the 

 platina to a red heat before using it, so as to drive away 

 a film of air which always rests on polished surfaces, 

 and which wonderfully lessens the power of the battery 

 by preventing the direct access of the acid to the platina 



SMI f;i' p c. 



Bunaen's carbon battery is exactly the same as Grove's, 

 with the exception that some form of charcoal is em- 

 ployed in place of platina. The plate may be cut out of 

 the carbon which forms the inside lining of gas-retorts, 

 ii- may be made by pounding coke and making it into 

 a paste, with sugar, <kc., and pressing it into a mould 

 to obtain the proper shape. The mass is afterwards 

 heated to a red heat, and allowed to cool gradually. 



Iron, especially in the cast state, has the singular 



