200 Miscellanies. 



taic agency, but also in imparting to the clay a laminated or schistose 

 sti'ucture; the veins and laminae being perpendicular to the voltaic 

 forces. In some instances only a pair of plates, or in preference cop- 

 per pyrites and zinc, were employed to produce the voltaic action ; 

 but a constant battery consisting of several pairs of plates was much 

 more effective. Among the veins thus produced in clay, Mr. Fox 

 mentions oxide and carbonate of copper, carbonate of zinc, oxides of 

 iron and tin. Veins of carbonate of zinc were formed, sufficiently 

 firm to admit of being taken out in plates of the size of a shilling. 

 Mr. Fox then describes a vein formed in pipe-clay, by Mr. Jordan, 

 by five pairs of cylinders, in three weeks. The clay divided an earth- 

 enware vessel into two cells, in one of which, containing the cop- 

 per plate, a solution of sulphate of copper was put ; and in the oth- 

 er, or zinc cell, a solution of common salt. Well-defined veins were 

 thus produced of carbonate and oxide of copper, and carbonate of 

 zinc, parallel to the laminfe into which the clay divided ; as well as 

 another of carbonate and oxide of copper at right angles to them. 

 On dividing the mass of clay in the direction of the principal hori- 

 zontal vein, the carbonate of zinc was found on the negative side, or 

 towards the copper plate : and the carbonate of copper nearest the 

 zinc plate: and as the former must have been derived from the zinc 

 plate, it is curious to observe such a complete transposition of the 

 respective metals. 



Mr. Fox is of opinion that these results have a strong bearing on 

 the numerous mineral veins and beds which are found conformable to 

 the direction of the laminae of the containing rocks, as well as on 

 those veins which traverse the lamina of the conformable veins. — Ih. 



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