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III. Description of a Mercurial Voltaic Conductor. By 

 W. H. Pepys, Esq. F.R.S.* 

 The advantages obtained by perfect contact in Voltaic 

 conductors is well known to the experimentalist, particu- 

 larly when the combinations or series of plates are but few. 

 Hence the slightest oxidation or corrosion of the wires de- 

 stroys more than half the effect. 



Having with others noticed the complete contact which 

 quicksilver gives, I had an apparatus so constructed as to 

 unite this advantage with the facility of using the wires or 

 conductors in almost all the modifications that are required 

 in the valuable and interesting experiments of Sir H. Davy 

 on the electrical laws of chemical decomposition. 



This apparatus has also another claim to notice, from 

 the operator not being so likely to receive the charge, when 

 the combinations are extensive, the adjusting-sliders being 

 non-conductors of electricity. 



With this apparatus and a series of six troughs of ten 

 four-inch plates, I have decompounded solutions of the 

 neutral and several of the more solid salts, such as gypsum, 

 chalk, and fluor spar; deflagrated charcoal, phosphorus, and 

 the metals ; and formed the alloys of sodium, potassium, 

 3nd ammonium with mercury. 



Reference to Plate I. 



Transparent Fiew of the Apparatus, showing the Inside 



Arrangements of the Box. 



A and B. Two cells formed by a partition of glass at C. 

 They are to be filled about a third with quicksilver. 



P and E. The negative and positive conducting wires 

 from the Voltaic battery entering the quicksilver in the 

 cells. 



F and G. Two tubes of glass filled with quicksilver, with 

 plaiina wires cemented into their lower ends, attached 

 to sliders in the top of the box, and moving freely in the 

 cells of quicksilver beneath. 



Hand I. Twomoveableplatina wires entering the glass tubes 

 in contact with the mercury. These wires are variously 

 formed at the will of the operator : those shown in the 

 apparatus arc pointed at one end, and being slightly 

 bent at the other may be adjusted to any heights in the 

 quicksilver ot the tubes. 



K. I'latina crayon- holder for receiving slips of charcoal or 

 rolls of metallic leaf for deflagration. 



L, M, and N. Series of one, two, and three vessels (in 



• Commuujcatcd by Mr. Pepys. 



Stand* 



