Observations on Electricity. 353 
errors Were committed, and on the first trial it made only eighty 
revolutions a minute. The remodeling was delayed until fur- 
ther subscription should warrant the proceeding; and I regret to 
learn that the recent disastrous fire in Boston has destroyed the 
machine and batteries. 
Art. [X.— Observations on Electricity ; by Cuarues G. Pace, 
M. D., Washington, D. C. 
It is somewhat singular that the following fact has so long re- 
mained in obscurity, especially as the Franklinian theory has de- 
rived its principal support from the converse of this fact: “Ifa 
pith ball be laid in a groove on the table of the universal discharger, 
and a Leyden jar or battery be discharged in the direction of the 
groove, the ball will be propelled in the direction of the passage 
of the fluid, that is, from the positive to the negative.” It must 
have happened, that in every case of repetition of this experiment, 
the jar was charged in the ordinary way, viz. the interior or 2~- 
Sulated coating charged with vitreous or positive electricity ; for 
it will be found that if the insulated coating be charged with 
negative or resinous electricity, the ball will be propelled contrary 
to the supposed direction of the fluid, that is, it will move from 
Negative to positive. “If a card be placed upon the table of the 
universal discharger, and the wires or directors be brought into 
Contact with the card on opposite sides, but at some distance 
from each other, the perforation made by a discharge between 
the points, will be found nearer the negative than the positive 
wire.” By reversing the experiment the same error will be foun 
in this statement, If the negative surface be insulated, the per- 
foration takes place nearest the positive wire. ‘The same correc- 
tion will apply to the experiment with the flame of a candle be- 
tween two cups of phosphorus. 
Curious result from the configuration of the electric spark at 
the positive and negative surfaces. If a tapering jet from which 
Issues a stream of hydrogen gas be applied to a conductor charged 
Positively, the gas will be inflamed nearly every time the spark 
| is drawn ; but if the conductor be charged negatively, the gas 
Will rarely be kindled, frequently requiring six or more applica- 
_ “ons before it succeeds. 
Vol. XxXv1, No. 2.—April—July, 1839. 45 
