BEFORE AND AFTER COMPLETION OF THE VOLTAIC CIRCUIT. 
47 
to complete the circuit ; for I wished to test an intermediate stage between actual 
insulation and actual completion of circuit, in order to discover the character of the 
discharges effected by touching the respective terminals, or rather their influence 
over the state of tension, into which the whole series was thrown. I wished, for 
instance, to discover whether the discharge I effected, threw the elements of the 
battery back, into the normal condition which prevailed antecedent to the discharge; 
or whether it threw them forward by completing the act of chemical combination, the 
preparatory state of which already existed ; whether, for instance, mere discharge, 
either by the earth or by completion of the circuit, for an instant, is one small frac- 
tion of a current ; and, if so, whether a current is not really a collection of discharges 
of electricity of tension. 
29. For this purpose the following experiments were made: a copper wire at- 
tached to N of the battery was connected with the galvanometer, and this with the 
plate a of the double electroscope, fig. 4. A platinum wire was attached to P of 
the battery, the end of which rested on a piece of bibulous paper saturated with a so- 
lution of iodide of potassium : another platinum wire, also resting on the paper, was 
connected with the other plate b of the electroscope ; by the mechanical arrangement 
of this instrument, the plates could be approximated or separated as required. Fig. 
7 shows the arrangement; N and P, the terminals of the battery; G, the galvano- 
meter; a and b, the plates of the electroscope S, solution of iodide of potassium. 
30. When the plates a and b were approximated so as to permit sparks to pass 
at intervals of about a second, a tremulous motion was imparted to the needle ; but 
when they were brought so nearly in contact as to permit the discharges to take 
place in quick succession, the needle was steadily deflected, and iodine freely evolved ; 
proving that chemical action was occurring in each cell, and that the current is a 
collection or an accumulation of discharges of electricity of tension ; for although 
the circuit was completed by distinct and separate discharges, still the deflection of 
the needle was as steady as if the discs had been in actual metallic contact. 
31. The discs a and b were then separated to the distance of about an inch; a 
piece of tinfoil was suspended by means of a thread of white silk ; the tinfoil vibrated 
between the plates, but no effect could be produced on iodide of potassium or on the 
galvanometer. 
32. I have already alluded to the extreme difficulty I experienced in effecting per- 
fect insulation. I was anxious to ascertain whether this insulation, and at the 
same time a high state of intensity, could be obtained, and whether, in such a state, 
any evidence of chemical action could be detected when one end of the battery was 
in connection with the ground. After many trials, I succeeded in insulating 320 
cells ; and so efficient was even this reduced number in point of intensity, that sparks 
could be obtained by means of the micrometer electrometer through a space of r^oth 
of an inch. The ends of two platinum wires were then fixed so as to rest on a 
piece of bibulous paper saturated with a solution of iodide of potassium. One of the 
