Mr Kemp rni a New Kind of Galvanic Trough. 75 



in the pile : and consequently the more rapid the combustion. In the solid pile, 

 the quantity of electricity seems to be generated in a progressive manner ; 

 and it is only at the moment of contact that combustion takes place, (at least 

 when the plates are small), some time being always necessary to recover its 

 electric state. 



If a very perfect conductor, such as a metallic wire, be made to form the cir- 

 cuit, the generation of the electricity in the pile is astonishingly increased. 

 These experiments all tend to prove, that the action in the pile is exactly 

 proportionate to the conducting power of the substance employed to form the 

 circuit. 



The electro-magnetic phenomena which it presents are no kss interesting. 

 Having rendered a common sewing needle magnetic, and suspended it by a sin- 

 gle fibre of silk, I brought the connecting wire over it, at the distance of an 

 inch and a-half, and the energy was of sufficient intensity to cause it to stand 

 at right angles to its natural position ; nor was the effect much decreased when, 

 instead of twelve, I only used two of the cups. 



The same effect could not be produced by a battery of sixty plates four 

 inches square. 



Another cause of the increase of power in this pile besides liquidity i^ 

 that almost no oxide is formed on the surface of the amalgam of zinc and mer- 

 cury, as is the case when a solid metal is used ; for, as soon as the particles of 

 zinc come in contact with the acid, they become oxidated ; and as there is not 

 the same cohesive attraction to hold them together as in the solid <metals, they 

 are immediately dissolved and taken up by the acid, the amalgam always 

 presenting to the action of the acid a surface perfectly clear, free from oxide, 

 and in the most favourable circumstances for generating and transmitting the 

 galvanic state. 



II. On a New Galvanic Trough. — Another galvanic appara- 

 tus, which I shall at present describe, is in the form of a trough, 

 and is chiefly composed of liquids. 



AB, Fig. 5. Plate II. is a wooden trough, eighteen inches long, four and a 

 half broad, and about two inches deep, divided into nine equal parts by strips 

 of glass aaa^ &c. fully a quarter of an inch in height. These spaces are again 

 subdivided by plates of glass hbh^ &c. nearly the whole depth of the trough, 

 each cell being rendered quite tight by a coating of wax. The trough will now 

 be divided into eighteen separate spaces or cells, the first and last being form- 

 ed by means of the higher plates, the others by a low and high one alternately. 

 The trough being prepared in this manner, a quantity of pure mercury, merely 

 sufficient to cover the bottom, is poured into the first space ; and into the se- 

 cond space the same quantity of the liquid amalgam of zinc and mercury ; in- 

 to the third space pure mercury; and into the fourth the amalgam ; and in like 

 manner, until the whole spaces are charged. 



By this means, we obtain a galvanic arrangement, consisting of pure mer- 

 cury and an amalgam of mercury and zinc. 



It will be observed, that the mercury in the first space is separated by one 



