ELECTRICAL ACTIVITY OF ORE BODIES. 

 Table VII. 



335 



vn 

 vn' 

 vm 



XI 

 XI' 

 XII 



XIV 

 XVI 

 XVII 

 XV 



Bemarks. 



FeiTuginoas, calcareous earth, in chamber 12, 

 Hard, fissared limestone. 

 Limestone, compact, porous, moist. 



Do. 



Do. 



Do. 



Limestone, very porous, near contact nf chamber 



Ferruginous earth. 



Red ocher, near bunch of ore i 



.„ . , i Chamber No. 



Ferruginous earth > 



Pocket of lead carbonate ore in limestone. 



Hard, impervious limestone and calcspar. 



Hard, solid limestone. 



Ferruginous earth, with galena 



Black iron ore, loose dry 



Ferruginous earth, with galena 



Ferruginous earth, without galena 



Large breast of lead carbonate ore 



Ferruginous earth, very dry 



Large breast of lead carbonate ore 



The results of the measurements of electromotive force between P. C. 

 in chamber 12 and the consecutive T. C.^s are given in Table VIII. The 

 general method of obtaining them has already been described (see page 329). 

 Intensities (i) are given in absolute electromagnetic units (G. G. 8.); electro- 

 motive forces (e) in volts, and these are arbitrarily considered positive 

 when the potential of T. C. is the greater, or when the lode current flows 



C wire 1 



(earth's 



T. a 



-> P. c. 



It will be remembered that, throughout, four terminal bags. A, B, C, B, 

 were used. The results obtained with AB are given in Series I., where, 

 moreover, i' is the intensity observed with the bags A and B in any partic- 

 ular position (say A in hole P. C, and B in T. C.) ; i" the intensity observed 

 when the bags are exchanged {B in hole P. C, and A in hole T. C); finally, 

 i'", the observed intensity when the bags again have their original position, 

 e is the corrected lode electromotive force between P. C. and the T. C. 

 specified. Series II. contains the corresponding results with the bags A and 

 C; Series III., with A and D. 



Finally, Series I., II., and III. were obtained in surveying from point 



