hie 161 J. - 
®€ MXVIL. On Electricity. By Ez. Wavker, Esq. 
rth "To Mr. Tillach. 
Sir, Pee all the hypotheses that have been invented to 
explain the phenomena of electricity, philosophers still en-_ 
tertain various opinions respecting the electric fluid. Some 
maintain that the spark is produced by two fluids passing 
through each other in contrary directions, forming a double 
current; but others are of opinion, that it consists 6f only 
ene divided into two parts, which they call positive and 
negative electricity ; whilst others even hesitate to admit 
the existence of the electric fluid, as completely established. 
As many of the phenomena of nature are produced by 
electrical energy, and a3 % conclusion drawn from doubt- 
ful principles can be admitted in philosophy, it seems in- 
dispensably necessary, that this disputed point should be 
determined by clear and satisfactory experiments. 
When a card is perforated by an electric spark, it is well 
known that a bur is raised on each side. This experiment 
has ofien been advanced as a proof that two positive powers 
pass through the card in contrary directions; but this con- 
clusion is too hypothetical to be admitted as a physical 
truth, and every other experiment that has yet been made 
to investigate this point, is equally uncertain. 
As many of the effects of electricity are strictly mechani+ 
cal; the following experiments demonstrate, on that prin- 
ciple, that the clectric spark consists of two forces passing 
through each other in contrary directions. 
- Experiment 1. Let a piece of tin-foil, about two inches 
Jong and an inch broad, be laid between two cards, with 
their ends fixed together with gum-water or varnish ; and 
Jet ABCD (fig. 2. Plate II.) represent those cards when 
laid on a table, ep apiece of wire Jaid upon the cards, and 
nh another piece of wire laid under them; the distance he 
between the ends of the wires being about an inch. 
A charge from a large Leyden jar being passed through 
the wires, a perforation was made in the top card at é, with 
an indent downwards, in the tin-foil and bottom card, un- 
der that point. The under card was also perforated at the 
end of the wire A, and a! that point the tin-foil and upper 
card were indented upwards, 
_ This experiment was repeated many times, without any 
Variation in the phenomena, except that one end of the 
tin-foil was sometimes perforated. 
Now it is evident from this experiment, that the power 
Yol.42, No. £85, Sept, 1813. I, from 
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