98 Prof. Faraday on Electric Conduction, 



driven onwards by an oceanic current, except that the iceberg 

 would perhaps have the power, from the causes above specified, 

 of even more closely moulding itself, and, as it were, oi flowing 

 straight over submarine obstacles, than has a glacier on the diy 

 land. 



One other point is perhaps worth considering. I have else- 

 where* endeavoured to show that the action of coast-ice and of 

 icebergs must be considerably diflferent in transporting boulders ; 

 the worn stones on the beach being imbedded in coast-ice, and 

 fragments of rock which had originally fallen on the parent- 

 glacier being carried by icebergs as on rafts. But when we 

 reflect that icebergs are driven onwards year after year in certain 

 definite directions by the ciu'rcnts of the sea, — that they float so 

 deeply as to have been seen agi'ound at the depth of 1500 feet, — 

 that when stranded they must (as I conceive) mould themselves to 

 the inequalities of the bottom and slide some distance over it, — 

 it can hardly be doubted that they also must, like glaciers on 

 the land, push in certain determinate directions moraines before 

 them. Although a fragment of rock or an irregularly formed 

 moraine may by any one iceberg be propelled for only a very short 

 distance, yet in the course of years the trans portal can hardly 

 fail to become far extended, the boulders being rolled over large 

 inequalities of surface, and even up heights by the action of suc- 

 cessively smaller bei'gs : an abyss, however, deeper than the 

 deepest-floating iceberg would, of course, absolutely stop this 

 rolling or pushing action. Finally, in the case of every mass of 

 erratic boulders, we have now to determine, and I believe here- 

 after it will be so determined, whether they were transported by 

 glaciers or by floating ice, and in this latter case whether im- 

 bedded in coast-ice, strewed on the surface of icebergs, or pushed 

 onwards as a subaqueous moraine. 



XIII. On Electric Conduction. 

 Bij Professor Faraday, D.C.L., F.R.S.f 



SINCE the time when the law of definite electrolytic action 

 was first laid down (Exp. Res. 783-966), it has become a 

 question whether those bodies which form the class of electrolytes 

 conduct only whilst they ai'c undergoing their proper change 

 under the action of the electric current ; or whether they can 

 conduct also as metals, dry wood, spermaceti, &c., do in different 



* Transactions of the Geological Society, vol. vi. (2n(l series) 1841. 

 p. 430. 



t From the Proceedings of the Roj'al Institution of Great Britain, for 

 Friday, May 25, 1865. 



