ON THE ELECTRIC COLUMN. 83 



will relate to the electric column^ considered only as the 

 electric efficiency in the pile, divested of either chemical or 

 phj/siological cri^ticts. The second will explain the difficulties 

 which 1 have encountered in attempting to bring the instru- 

 ment to its de&irable function as aerial electroscope, and the 

 point which I have attained in this new kind of metcorologi" 

 cat observations. And in the third, I shall otier to the at- 

 tention of the natural philosopher, some meteorological oh' 

 servations, which show the importance, in every branch of 

 experimental philosophy, and especially in chemical theo- 

 ries, of forwarding the observation of atmospheric pheno- 

 mena. 



On the Electric Column. 



I have explained in the first paper my system concerning Cause ofthp 

 the cause of a moiinv. of the electric Jiuid, produced by the ^f^ ' '* 

 properties of two associated metals; and as all the circum- 

 stances attending this motion are characteristic of its cause, 

 this connexion w;ll be here my principal object. 



I shall begin by some experiments under the same form 

 as Exp. 4 in the former paper, in which the brass tripods 

 were placed between the two metals, and these grotips sepa- 

 rated by pieces of wet chth. In this first dissection of the Electric and 

 pile, both electric 'And chemkal effects were produced, the fg^^fj^''^^ 

 latter on account of the water contained in the cloth ; and 

 I wanted to know what would be the consequence, in the 

 same arrangement, with respect to the electric effects of The chemical 

 suppressing the cA^wjica/ ones, by a dre/ intermediary sub-^"^^"^^^ 

 stance. For this purpose, I substituted for the silver p'ates 

 and the wet cloth of the former experiment pieces oi' Dutch 

 gilt paper, placing the brass tripods between the zinc plates 

 and the copper side of the papers; atid after having found, 

 that 40 such groups could be contained in each column of 

 the frame described in that paper, forming in the whole 80 

 groups, 1 made the following experiments. 



Exp. 1. In order to judge what would be the effect of Exp. 1. 

 interposing the brass tripods between the metals, I first 

 mounted the 80 groups without them, and observed the de- 

 G 2 gree 



