'Edhiburgh Institute. 3 1 1 



«\x Inches square, while in action by means of dilute J .sul- 

 phuric acid, produces so powerful an effect as to be able to 

 deflacrrate 18 inches of platina wire; an effect which has 

 rarely been exhibited by the trough, even with plates ot 

 larger surface, and an equal number of pairs. It may he 

 just mentioned as one reason of the superior action ot the 

 battery of Mr. Jackson's construction, that the chemical 

 atrenti employed in it, namely, the sulphuric acid, could 

 not be used in the trough, even when very largely diluted, 

 without 'producing so violent an action as to injure the 

 apparatus, and to render its operation extremely incommo- 



*iit)us. ^ ^ , • 1 u • c 



As connected with the subject of Galvstnism, the briet 

 account of an experiment which shows to what distance 

 the Galvanic fluid may be conveyed through water, will 

 not, [ trust, be deemed out of place. The experiment al- 

 luded to was first suggested by Mr. Jackson, and was made 

 by him, some years ago, in presence of several gentlemea 

 belonging to the University. For the purpose of having 

 the fact fully verified, the same experiment w\is repeated 

 yesterday, with his portable apparatus of 40 pairs of two 

 inches. The battery was placed on a rock in the bed of the 

 water of Lellh, and a wire from one end was introduced 

 into the river, a few feet from the apparatus : a wire at- 

 tached to the other end of the battery, and extending 60 

 yards in length, was carried along the dry bank: the end 

 of this wire 'was taken in one hand moistened with water, 

 and the other hand was dipped into the river; and althougU 

 the circuit thus formed was equal to 120 yards, or 3G0 feet, 

 yet the shock irom so small an apparatus was quite per- 

 ceptii)Ie. It was still more sensible when the hand was 

 dipped in the river, and the tongue was applied to the wire. 

 The decomposition of water proceeded rapidly; but the 

 wind prevented a fair trial of the deflagration of metals, 

 and some other experiments which were proposed. In a 

 former experiment, Mr. Jackson found that metals were re- 

 vived from their solution in acids by the same apparatus, 

 and when the extent of the circuit was not much less. In 

 the course of these experiments, I had an opportunity of 

 witnessing the remarkable effects of the conducting power 

 of bodies, which, indeed, 1 ought to notice, was observed 

 by Mr. Jackson at the time he made the first experiment. 

 When the wire from one end of the battery was brought 

 into contact with the tongue, at the distance of several 

 yards from it, I perceived a strong metallic taste, or rather 

 '' U4 received 



