346 Mr. Grove on the Gas Voltaic Battery. 



Hill near Callington, displays nothing but neutral beds, or 

 interchanges, or interlockings, of killas and carbonaceous 

 rocks, or of carbonaceous rocks fracturing and piercing through 

 the killas prior to the latter overwhelming them by its enor- 

 mous accumulations. 



The Boscastle sections however, on the other hand, are 

 so readily comprehensible and simple as scarcely to admit a 

 doubt of it, corroborated as they are by the coast cliffs to 

 Tintagel, where the anthracitic schists, which are seen in mass 

 at Boscastle supporting the killas in almost a tabular form, 

 are observed to be continued upwards among the pale green 

 roofing-slates by repeated interpolations, of which ready ex- 

 amples may be seen close by the church at Trevalga, and a 

 little further south at Treworthat. 



Such are the natural subdivisions of the great killas group, 

 founded on peculiarly appropriate types and continuity of 

 series, guided by which I trust I have sufficiently shown that 

 I have relied on, or been misled by, nothing which was arbi- 

 trary or inconstant. 



Its position as the crowning extremity of a magnificent, 

 consecutive, and abundantly-varied series (as yet unrivalled 

 by any hitherto developed by rigid and direct analysis), 1 

 have endeavoured to show as clearly and in as much detail as 

 the nature of the communication admits, and so far its place 

 in the European system may be determined and mapped down 

 with certainty, if it shall eventually be shown, as I confidently 

 anticipate it will be, that I have been correct in my views, 

 that the entire Devonian and Cornish group is based on (pro- 

 bably the upper beds of) the old red sandstone. 



L. On the Gas Voltaic Battery. — Experiments made with a 

 view of ascertaining the rationale of its action and its ap- 

 plication to Eudiometry. By W. R. Grove, Esq., M.A., 

 E.R.S., Professor of Experimental Philosophy in the London 

 Institution. 



(Continued from p. 278.) 



TpXPERIMENT 7,-1 charged two batteries of two cells 

 -^ each, with hydrogen and dilute sulphuric acid in the 

 alternate cells. When tested by iodide of potassium, each 

 battery gave notable effects. One of these batteries was then 

 placed, together with a cup containing phosphorus, in a 

 shallow vessel of water; the phosphorus was ignited and a 

 large glass vessel inverted over the whole; the terminal wires 

 of the battery, carefully protected by thick coatings of cement, 

 passed under the edge of this vessel through the water, the 



