Mr Fox an the Lamination of Clay by Electricity, 197 



sits and other bases from their solutions. These results, which, 

 however, were much more marked in some experiments than ia 

 others, seem to confirm the correctness of the views stated in 

 the last Polytechnic Report, pp. 87, 88.* 



Indeed, the general laminated structure of the clay appears 

 to indicate, that a series of voltaic poles were produced through- 

 out the clay, the symmetrical arrangement of which had a cor- 

 responding effect on the structure of the clay. This view is 

 still more strikingly confirmed by the occurrence, in several 

 instances, of veins, or rather lamina^ of oxide of iron, the edges 

 of which are shewn by the shaded lines A:, Z, m. In these cases 

 sulphate of iron was substituted for the sulphate of zinc ; and 

 laminae of oxide of copper were sometimes formed in like man- 

 ner, when a solution of that metal was employed ; and, more- 

 over, numerous minute insulated portions or specks of the oxide 

 of copper were detected in different parts of the mass of clay 

 when broken.*!* 



The coloured laminae produced in some of these experiments, 

 have, apparently, a direct bearing on the variously coloured 

 and waving lines which the edges of the laminae of schistose 

 rocks so commonly present, and also, on the occasional deposi- 

 tion of metalliferous substances parallel to the cleavage, which 

 seem to liave been formed on or before the consolidation of the 

 rocks. The true veins, however, were evidently formed after 

 the consolidation of the latter; and as they generally intersect, 

 in Comwall at least, the laminae of the " killas '^ or clay-slate, 

 at more or less considerable angles, they seem to have acted 

 the part of the copper wire shewn at i, in completing the vol- 

 taic circuit. 



Hence arises the question whether the productiveness of 

 lodes, depends more or less on their bearings with respect to 

 to those of the cleavage ; and it appears to be a matter of prac- 

 tical importance to ascertain these relations in our mining dis- 

 tricts, and especially to note the angles at which the laminae 



* We have not seen the last Report mentioned above. Edit. 



t Some of these effects were apparently most decided when a series of vol- 

 taic exciters were used so as to increase the energy of the action, — three or 

 four such cups for instance as shewn in the Fig. arranged so as to form a 

 complete circuit. 



