238 On Mineral Veins. 
the zinc plate along the strip of copper to the copper plate, 
and from the latter through the wall of clay to the zine 
plate. The action was kept up for six months by daily 
additions to the solutions, when the clay wall was examined 
and found to have assumed the conditions described by Mr. 
Fox. On the side next the zinc plate, the clay was tra- 
versed by distinct lines of cleavage parallel to the sides of 
the clay wall. On the copper side, instead of the vertical 
laminated structure, there was a consolidation of the mass ; 
this consolidation appearing to take place in the direction of 
the current; the induration in many places being very 
striking, and the fluid and clay were considerably elevated 
on that side. This action produced a hollow in the centre 
of the mass, and a series of curved lines proceeding from the 
top of the zinc plate towards the centre of the copper plate, 
and from thence back towards the bottom of the zine 
plate. As these curved lines approached the zine side, they 
were crossed and split by the vertical laminations, although 
very distinctly continued. A dark band was formed on the 
curved lines, and in this near the copper plate laminz of 
copper were found, while at a greater distance from the plate 
the metallic copper in the laminze was replaced by carbonates 
of copper and zinc. A number of nodules were also formed 
on the lines of the magnetic currents. 
This experiment indicates that two forces or lines of power 
were in operation ; one of them producing cleavage lamina- 
tions similar in character to those trav ersing the schistose 
rocks, the other exerting a drawing action towards the 
copper plate ; elevating the clay on that side and leaving a 
cavity in the centre. At the same time a molecular change 
of structure was going on, as indicated by the formation of 
nodules in the clay ; and not only were the metals employed 
removed and deposited in the laminations of the clay, but 
by the same agent the ores of these metals had been formed 
and deposited ¢ on the laminations under the same conditions 
as they are found in mineral veins. 
If on this small scale, and in such a comparatively short 
period of time, these effects can be produced, it is easy to 
conceive how powerful may be the action of magnetic currents 
circulating in the crust of the earth—how readily the pheno- 
mena we now observe may be produced by them—and how 
varied these phenomena may become through the disturbing 
influence of peculiar local conditions. It is probable that here 
we have the principal agent in the formation of the cleavage 
