j)ld FAhlurgh Institute, 



struction answers the purpose; and, with a little inge- 

 nious contrivance, a temporary frame may scarcely ever be 

 wantinc:. 



3. It is unnecessary to mention to those acquainted wiih 

 Galvanic apparatus, that it is oF great importance to keep 

 the surface of the plates clean, so tliat the chemical solution 

 may act on the metallic matter to produce the efTect. The 

 apparatus before us possesses this advantage in a high de- 

 gree ; because the plates, being in detached pairs, can be 

 easily cleaned, so as always to exhibit, at the commence- 

 ment of every new operation, all their metallic brightness. 



4. But it is one of the peculiar advantages of this appa- 

 ratus, that its operation is attended with scarcely any ex- 

 pense. It has been one of the great objections to the use 

 of the Galvanic battery, in the form of the trough, that the 

 rpnntity of nitric acid, to bring a powerful apparatus into 

 full action, renders the expense enormous ; fur it is found 

 that the effects of the cheaper acids are too rapid and vio- 

 lent: but in this apparatus the cheaper acids, as the mu- 

 riatic or sulphuric, can be conveniently employed, since the 

 violence of its action is moderated by the mode of its appli- 

 iialion, through tb.e intervention of the pieces of cloth ; and 

 yet the power of its action seems to be greater than bat- 

 teries of a diflcrent construction having the same number 

 of plates in tlie series, and the same extent of surface. 



The apparatus now described has been found to be ex- 

 tremely convenient in the application of Galvanism to me- 

 dical purposes. For these purposes, I believe, Mr. Jackson 

 first thought of it, and has long and pretty extensively cm- 

 ployed it in this way ; and 40 pairs of two inches square 

 form a battery of sufficient power for this purpose. * 



But batteries of a greater number of series, and of greater 

 extent of surface, have been constructed by Mr. Jackson on 

 the same plan ; a battery, consisting of 100 pairs of plates 

 of four inches square, was fitted up ; and u hen the cloths 

 were moistened with sulphuric acid diluted with water, 

 the power of action of this battery seemed to be superior to 

 that of the trough, composed of an equal number and of 

 an equal surfrce of pairs of plates; I say seemed, for no 

 comparative experiments Iiave been yet instituted to ascer- 

 tain this point, on which I expected to have been able to lay 

 some observations before the Institute at this meeting; but 

 as the experiments are not yet completed, I must reserve 

 them to a future commimication. Here, too, it may be 

 added; that a battery constructed of 100 pairs of plates of 



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