GALVANIC APPARATUS. "jg 



V. 



Defcription of a Galvanic Apparatus affording a large Surface 

 for Oxidation, and convertible into one or more Plates at plea- 

 fare. By I. R. I. 



To iMr. NICHOLSON. 



S I R, Edinburgh, May 10, 1804.. 



1 AM much flattered by the notice that you and Mr. Wil- 

 kinfon have been pleafed to take of my late communication, 

 and I think I have done no fmall fervice to fcience by draw- 

 ing forth from both of you, the very ingenious difquifitions to- 

 wards the osconomyof galvanifm, which appeared in yourlaft 

 Journal. 



Your defcription of what may be called a Polychreft trough, Improvement in 

 feems to reach as near perfe6lion, in every requifite property the galvanic 

 for giving the fliock, or deflagrating metals, as could be wi{hed: " 

 Yet there is ftill a further improvement which has fuggefted 

 ilfelf to my mind ; but as it is probable the wafte of the zinc 

 would be more confiderable, I mention it with diffidence. 



It appeared to me in fome experiments I made with the Corrofion great- 

 couronne de iajfes, that the metals were more corroded to pro- ^^ •" the ecu- 

 dace the fame eflfe^l, than happened either in the pile or the "*""* ^ ^•""' 

 trough ; but if Mr. W.'s, idea is juft (which is moft likely to 

 be, from his great experience in the fcience), that the efl^e6l 

 is in proportion to the oxigenation of the metal, the following 

 plan appears the be(i adapted for both oeconomyand power. 



In Fig. 3, Plate VI. A reprefents, by a fide view or fedion, Defcription. 

 a plate of zinc of fix inches by three ; in its centre is a fquare 

 piece, from which rifes another piece of a fmaller diameter, 

 either fquare or round. Thefe proje6ting bits are both funk 

 in a block of wood fomewhat larger than the whole plate, but 

 not fo as to pafs through it ; and the plate muft ftand clear of 

 the wood and every part of the cell, hanging entirely by the 

 knob, and ftrongly cemented. A bore is made dpwn througli 

 the thicknefs of the wood, in a line with one through the fraall 

 knob of the. zinc. 



The copper wire B, pafTed through that hole, is the medium 

 of communication from cell to cell; and the fame mode may 



be 



