Galvanic Batteries. J 71 



which both the trough containing the plates and another trough to 

 collect and hold the liquid are fixed. This arrangement I have found 

 the most convenient of any, and have therefore adopted it." 



Here follows an engraving and description of the deflagrator which 

 the celebrated author constructed agreeably to the principles of Dr. 

 Hare's, after which he proceeds to say — 



" Such was the facility afforded by this arrangement, that a trough 

 of forty pairs of plates could be unpacked in five minutes, and re- 

 packed again in half an hour ; and the whole series was not more 

 than fifteen inches in length. 



"This trough of forty pairs of plates three inches square was com- 

 pared as to the ignition of a platina wire, the discharge between points 

 of charcoal, the shock on the human frame, &.C., with forty pairs of 

 four-inch plates having double coppers, and used in porcelain troughs 

 divided into insulating cells, the strength of the acid employed to ex- 

 cite both being the same. In all these eirTects the former appeared 

 quite equal to the latter. On comparing a second trough of the new 

 construction containing twenty pairs of four-inch plates with twenty 

 pairs of four-inch plates in porcelain troughs, excited by acids of the 

 same strength ; the new trough appeared to surpass the old one in 

 producing these eflfects, especially in the ignition of wire." 



We omit here a detail of the ingenious and accurate experiments 

 on which Mr. Faraday's inferences were founded, our object being 

 in this article to quote his conclusions, rather than his premises ; and 

 shall accordingly pass on to those portions of his paper in which the 

 former are communicated. 



" When ten pairs of the new arrangement were used, the consump- 

 tion of zinc at each plate was 6.76 equivalents, or 67.6 for the whole. 

 With ten pairs of the common construction, in a porcelain trough, 

 the zinc oxidized was, upon an average, 15.5 equivalents each plate, 

 or 155 for the entire trough. 



" No doubt, therefore, can remain of the equality or even the great 

 superiority of this form of voltaic battery over the best previously in 

 use, namely, that with double coppers, in which the cells are insula- 

 ted. The insulation of the coppers may therefore be dispensed with; 

 and it is that circumstance which principally permits of such other 

 alterations in the construction of the trough as gives it its practical 

 advantages. 



" The advantages of this form of trough are very numerous and 

 great. 1st. It is exceedingly compact, for one hundred pairs of plates 

 need not occupy a trough of more than three feet in length. 2d. By 

 Dr. Hare's plan of making the trough turn upon copper pivots which 

 rest upon copper bearings, the latter afford fixed terminations ; and 

 these I have found it very convenient to connect with two cups of 

 mercury, fastened in the front of the stand of the instrument. These 

 fixed terminations give the great advantage of arranging an apparatus 



