EXPERIMENTAL AND THEORETICAL.

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employed for separating the copper from the zinc of a Voltaic pair, I employed anunglazed stone-ware jar, which was kindly given to me by Mr. Gassiot, for a firsttrial. This jar is about six inches high and three and half diameter. It was partlyfilled with a solution of carbonate of soda, and placed in a larger jar of porcelain,which was afterwards filled about half way up with a solution of sulphate of copper.A cylinder of rolled copper, sufficiently large to envelop the diaphragm, was placedin the sulphate of copper, and a small cylinder of zinc, in metallic connection withthe former, was placed in the solution of soda. The liquids inside and outside of thestone-ware diaphragm were of precisely the same altitude. In three days a differenceof altitude in the two liquid columns was very perceptible; and in about ten daysfrom the commencement of the experiment, nearly the whole of the liquid in the zinccell was driven through the stone-ware partition into the outer compartment. Thecopper solution was so completely decomposed that scarcely a trace could be detectedby liquid ammonia; and but a very slight tinge was given to litmus paper, showingthat the acid liberated from the sulphate had been either neutralized by the soda ordecomposed by acting on the zinc ; or its disappearance was probably occasioned onboth these accounts. A thin crust of salt (probably sulphate of soda) covered themoisture which was left in the bottom of the diaphragm, and the zinc was much cor-roded and partially covered with a white matter, partly soluble and partly insolublein water, the latter portion being a carbonate of the oxide of zinc. I have repeatedthe experiment with precisely the same results, obtaining a difference of altitude offour inches in the two liquids, the filtration being always in the direction of the elec-tric current. I have also obtained similar electro-transportations of liquid mediathrough diaphragms of common tile and soft red brick, and I have no doubt of theirbeing obtainable by sandstone and even thick masses of granite.

W. S.

Description of a new Galvanic Battery.

The battery I am about to describe will be found exceedingly useful either for dis-play on the lecture table or an as an implement of research. It consists of a rectan-gular wooden box, as represented at the bottom of Plate XVIII. in which arecemented a series of Voltaic pairs of copper and zinc, in the Cruickshank form.Every cell formed by these metals is divided into two compartments by a diaphragmof mill-board, also cemented into the sides and bottom of the box, so as to be com-pletely water-tight. The figure represents six metallic pairs and five diaphragms, theformer by the light partitions and the latter by the shaded ones. As the mill-board ispervious to aqueous liquids, it is obvious that any two kinds may be employed which

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