426 New Outlines of Chemical Philosophy. 



5, An electrometer constructed according to Mr. Bonnet's 

 directions, and some other instruments used for the same i)ur- 

 pose. They are very ingenious inventions, but injproperly called 

 electrometers ; they are electroscopes, which indicate the ex- 

 istence of electricity, but not the quantity of it. 



From the following experiments it will aj)pear that some of 

 the principal hypotheses which have been invented to explain 

 the phpenomena of electricity are erroneous. 



Exp. 1. A barometer tube 4-lOths of an inch external dia- 

 meter being excited by rubbing it with silk, and held over the 

 top of the wire of one of the electrometers above described, for 

 a short time, at the distance of six, nine, or twelve inches, ac- 

 cording to the degree of excitement, or state of the air, the gold- 

 leaves will diverge to an angle between 90 and 1 80 degrees ; 

 and if ihe instrument be a good one, this angle will gradually 

 decrease during two or three days ; but these instruments in 

 general will not retain electricity (piite so long. 



Exp. 2. The barometer-tube being excited as before, and 

 held over one of the insulating stands with a gilt surface, at the 

 distance of three or four inches, for a short time, the narrow slip 

 of Dutch leaf stood erect for near two hours. At the end of that 

 time, the quantity of electricity which the gilt surface contained 

 was measured thus : the wire at the top of an electrometer be- 

 ing brought into contact with the edge of the gilt surface of the 

 glass, the leaves of tlie electrometer diverged, and the angle 

 being measured was found to contain .'50 degrees. The electro- 

 meter being discharged, by touching the wire Avith a finger, and 

 applied a second time to the gilt surface, the leaves diverged, 

 and the angle being measured was found to contain 30 degrees. 

 Thus the remaining quantity of electricity was measured, and 

 the sum of the angles indicated by the electrometer amounted to 

 1 10 degrees. 



The divergency of the leaves is measured by a graduated arc 

 placed against the outside of the jar, with its centre just as high 

 above the table on v/hich tlie instrument stands, as the angular 

 point of the two leaves. 



But the two electrometers described in this paper, vvill not 

 indicate the same number of degrees in a given quantity of elec- 

 tricity, because their leaves are of unequal dimensions. 



Eocp. 3. After one of the insulating stands A had been elec- 

 trified by induction, as in the last experiment, I took it up by 

 its foot and held it in an inverted position over the top of m- 

 other stand B for a little time ; the distance between their two 

 surfaces being about three inches. The slip of Dutch leaf up(*n 

 B^ being attracted by that on A, stood erect, but in a short time 

 the leaves ceased to indicate any electrical aignsj for the elec- 

 tricity 



