mere Contacl of coiduding Suljiances. 3O1 



with a glafs tube, or interpofing between them and the co- 

 himn a few ftripes of wax cloth, oiled paper, or even plain 

 paper, and, in a word, any other body that mav either be a 

 ohihcnt or ixhzA conduftor: wood or paper will be fuffici- 

 t'ntly»fo for ourpurpofe, provided only that they are not very 

 damp or moift. 



But the bed expedient, when vou-wifli to form an appa- 

 ratus to confill of a great number of plates, above 60, 80, 

 or 100 for example, is, to divide ihe colunm into two or 

 more, as feen Fig. 3 and 4, (Plate VIII.) where the pieces 

 all have their refpeftive pofitions and communication as if 

 there were only one column. Fig. 4, as well as Fig. 3, niay 

 indeed be confidered as a bent column. 



In all thefe figures the different metallic plates are denoted 

 by the letters S and Z (which are the initials of filver and 

 zinc) ; and the moijlencd dijh (of pafteboard, fkin, &c. in- 

 terpofed between each pair of metals), are reprefented by a 

 black Ib'atum. The plates of metal may either be laid fimply 

 upon each other and fo brought into union in an indefi- 

 nite number of points, or they may be foldered together. 

 It is altogether indifferent whichever of thefe methods be 

 followed, cc, cc, cc, are the metallic plates which form 

 a communication between each column, or feibon of a 

 column, and another; and bb, bi, bb, are the bafoiis of 

 water in communication with the lower part or extremities 

 of thefe columns. 



An apparatus thus prepared is exceedingly convenient 

 without being bulky ; and it niight be rendered portable, with 

 flill more eafe and fafety, bv means of circular cafes or 

 tubes, in which each column might be inclofed and preferved. 

 It is only to be regretted that it does not long continue in a 

 good ftate : the ir-oiftened difks become dry in one or two 

 days to fuch a degree that they muft be again moiftened ; 

 which, however, may be done without taking to pieces tho 

 whole apparatus, bv immcrfing the columns, compleielv 

 formed, in water, and wiping them, when taken out foine 

 time after, with a cloth, or in any other manner. 



The bed method of making an inftrument as durable n«: 

 eau be wiHiedj would be, to indole and confine the wstt i" 



Witcryo'iViJ 



