Page:Memoirs of the Geological Survey of Great Britain, Volume 1.djvu/464

Rh ON THE CONDITIONS OF MATTER.

451

into action by filling the trough with some chemically exciting fluids. The electricity thus excited passed by the copper connecting band to the copper-plate, and returned through the interposed mass, placing it in similar conditions to those we may imagine to prevail in nature.

44. Several arrangements of this kind have been made. Stourbridge clay, plaster of Paris, sandstone (the ordinary Bath scouring brick), and finely powdered coal have been used for the dividing mass. The exciting fluids have been diluted sulphuric acid in both cells. Sul- phate of copper in one (the copper) cell, and muriate of soda in the other, or sulphate of iron and muriate of ammonia. In general the voltaic action has been kept up for a month or six weeks to its first power, by a daily attention to the solutions, after which the fluid has been allowed to evaporate slowly away.

45. Masses of clay subjected to this action were found after some months to have assumed the conditions mentioned by Mr. Fox. On the side next the zinc plate, distinct lines of cleavage of a schistose character, parallel to the sides of the clay and the plate, or at right angles to the direction of the current presented themselves. These laminae, on drying the mass, were gradually contorted, and at length broken off. On the side next the copper plate instead of the laminated, structure, we find a consolidation of the mass ; this consolidation ap- pearing to take place in the direction of the current or very nearly so. The induration in many cases is very striking. In one experiment made with great care upon a mass of clay, weighing several pounds, where the action was continued from July 4th, 1845, to January 20th,

Fig. 12.

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