2 IMPROVEMENTS IN GALVANISM. 



penny be foldered in its centre, and all the reft of that furface, 

 which is ufually Toldered to copper or filver, be well covered 

 with cement, ecjual effe6ts would be obtained. 



Proof in the In a Couronne de TatTes I find the fame effeds are pro- 



Couronne de duced, whether the copper be of a correfponding fize to the 

 zinc plates, or, whether they be merely limple copper or 

 lilver wires. 



and In a pile. Upon this principle I have conftru6ied a pile, and find it 



produces the fame effeds, as if the whole furface were 

 covered with copper ; I purpofe foon to arrange a trough 

 upon the fame principles, and I am perfuaded, that the more 

 tedious and expenfive part of galvanic apparatus may thus be 

 prevented. 



Theeorrofion in When a trough has beenfometiine employed, upon removing 



a trough IS the plates, the iofs of metal, I always obferve, does not take 

 greateft near the ^ . ' , r r i • > 



air. place uniformly over the furface, but in the upper part, whini 



in the galvanic action is the mofl expofed to the atraofphere, 



is the moft acted on, and towards the bottom, the metal i» 



very little altered. In order to preferve a more equal a6tion, 



I am now preparing a battery formed of plates of ten inches 



by two and a half, the longed fide placed horizontally, and I 



am perfuaded, tliat this fized plate will produce more a6live 



effeds than a plate of five inches fquare. 



Kcnce 3 pile of It is well known, that in every galvanic operation, oxida- 



'i/*" ^°°'<^ ^^ tion is produced, and if oxigen can be procured from the 



furrounding air, the effeft would be more eafy than producing 



it from the decompofition of water. I have no doubt, that 



if a feries of zinc plates formed like large pewter difhes, 



■were to be arranged in a pile-like form, infulated from each 



other, and the galvanic mixture to be poured in the hollow 



part; the lower fide being covered with cement, excepting 



that from the centre a piece of copper fhould be foldered, 



and fo projeding as to be in contadl with the fluid in the 



cavity of the plate below ; that a very powerful apparatus 



would thus eafiJy be formed. 



On the fubftitu- In the latter part of your Jortrnal I peru fed with a con- 



A^^P^f" '"' ^1*^^''^'^^^ degree of furprife, fome obfervations of a Mr. Dyck- 



mediums by hofT relative to the fubflitutions of thin ftrata of air, inflead 



DyckhofF, of vvet media. As the refults of his experiments appeared fo 



contrary in principle to any I liad tried, I immediately re- 



jjeated them in the manner he has defcribed, with interpofed 



5 lentils 



