OO 
_ Hare’s Single Leaf Electrometer. 103 
nieinieeil great, but the deflagrating power was not 
increased in proportion. The light was so intense, that 
falling upon some adjacent buildings, it had the appearance 
of sunshine. Having had another series of 300 pairs made 
for Dr. Macnevin of New-York, on trying it. I connected 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 sur- 
faces. The shock of the two, consecutively, was apparent- 
ly doubly as severe, as the shock produced by one; but 
the other eee seemed to me pearly equally bril- 
liant, in either 
The white amine which you atticed: were formed copi- 
ously on the ignited plumbago, especially in vacuo. I have 
not had leisure to test them, being arduously occupied, in 
my course of Lectures, and in some efforts to improve the 
means of eayesisnbntal illustration. 
Account of an Electrometer, with a single leaf, by which the 
electricity excited by the touch of heterogeneous metals, is 
rendered obvious, after a single contact. 
Fig. 7. represents an pp ee se a single leaf sus- 
pended from a disk of zinc, six ine n diameter, which 
constitutes the top of the instrument. “Op wosite to this sin- 
gle leaf, isa ball, supported on a wire, which may be made 
to approach the leafs or recede from it, by means ofa screw. 
Above the instrument, is seen a disk of copper, with a glass 
handle.* _The electricity produced by the contact of cop- 
and then lift this disk from the zinc. As soon as the sepa- 
ration is effected, the gold leaf will strike see ball usually, if 
the one be not more than ;3; of an inch, apart from the 
* For the > experiment with this electrometer a metallic rosie’ wos an- 
pas Its b comp in- 
ed, with that obtained by a condenser. 
