Harems Single Leaf Electrometer. Sol 



incapacity of the Deflagrator, and Voltaic series in the usual 

 form, to act, when in combination with each other ; must 

 justify us, in considering the former, as a galvanic instru- 

 ment, having great and peculiar powers. 



Since the above was written, I have tried my series of 

 300 pairs. The projectile power, and the shock, were 

 proportionally great, but the deflagrating power was not 

 increased in proportion. The light was so intense, that, 

 falling on some adjacent buildings,, it had fully the appear- 

 ance of sunshine. Having had another series of 300 pairs 

 made for Dr. Macnevin of New- York, on trying it, I con- 

 nected it with mine, both collaterally, and consecutively, 

 so as to make in the one case a series of six hundred, — in 

 the other a series, half that in number,but equal in extent 

 of surfaces. The shock of the two, consecutively, was ap- 

 parently doubly as severe, as the shock produced by 

 one ; but the other phenomena seemed to me nearly equal- 

 ly brilliant, in either way. 



The white globules which you noticed, were formed co- 

 piously on the ignited charcoal, especially in vacuo. I 

 have not had leisure, to test them, being arduously occu- 

 pied, in my course of Lectures, and in some efforts to im- 

 prove the means of experimental illustration. 



Account of an Electrometer with a single leaf hy which the 

 electricity excited hy the touch of heterogeneous metals, is 

 rendered obvious, after a single contact. 

 Fig. 7, represents an Electrometer, with a single leaf sus- 

 pended from a disk of zinc, six inches in diameter, which 

 constitutes the top of the instrument. Opposite to this 

 single leaf, is a ball, supported on a wire, which may be 

 made to approach the leaf; or recede from it, by means of 

 a screw. Above the instrument, is seen a disk of copper, 

 with a glass handle.* The electricity produced by the 

 contact of copper and zinc, is rendered sensible in the fol- 

 lowing manner. Place the disk of copper, on the disk of 

 zinc, (which forms the canopy of the Electrometer) : t:^ke 

 the micrometer screw in one hand, touch the copper disk 



*For the experiment with this electrometer a metallic handle would an- 

 swer. Its being of glass enabled me to compare the indication, thus ob' 

 tained, with that obtained by a condenser. 



