BEFORE AND AFTER COMPLETION OF THE VOLTAIC CIRCUIT. 
51 
the voltaic circuit (10. 1 1. ]/.), as well as of any perceptible development of chemical 
or dynamic action (18. 19.). 
4th. That when the circuit is completed, whether by actual contact of the terminals, 
or merely by approximating- them, so as to allow a succession of sparks, the dynamic 
effects on the galvanometer are the same (30.) ; each producing a steady deflection 
of the needle ; consequently that the current, even when the circuit is closed, may be 
regarded as a series of discharges of electricity of tension, succeeding each other with 
infinite rapidity. 
5th. That the rise of tension in a battery (the chemical affinities of its elements 
being feeble, as in the water battery) occupies a measurable portion of time (27.) • 
6th. That to produce static effects in the voltaic battery, it is indispensable that 
the elements should be such as can combine by their chemical affinities (34. 35.), 
that the higher those chemical affinities are exalted, the less is the number of elements 
required to exhibit the effects of tension (38. 39. 41. 42. 44 and 45.), and consequently, 
that the static effects elicited from a voltaic series are direct evidence of the first step 
towards chemical combination or dynamic action. 
The chemical effects, when obtained in the generality of the experiments described 
in this communication, are of course feeble; but they are precisely the same in 
character as those exhibited by the more powerful voltaic combinations ; and it may 
fairly be concluded that the rationale of each is the same, and that they only differ in 
the degree of action. 
Received April 12, 1844. 
Note. — 1 have recently constructed an instrument, by means of which the tension 
in a single series of the voltaic battery can with facility be tested without the aid of 
Zamboni’s pile. Fig. 8 represents the electroscope, in the construction of which I 
was in a great measure indebted to an apparatus described by Dr. Hare*. A is a 
glass vessel, the stem of which is well-coated with lac ; B, B', two copper wires passing 
through glass tubes and corks; D, D', gilt discs, each about two inches diameter, 
attached to the wires ; P, a copper plate with a wire passing through a glass tube ; to 
the end of the wire is attached a narrow strip of gold leaf, L. The discs must be 
adjusted with care, so as to allow the leaf to be equidistant from each. If B is con- 
nected by a wire attached to the platinum, and B' by another wire attached to the 
zinc of a single cell of the nitric acid battery, insulated on a plate of lac, and an ex- 
* Silliman’s Journal, vol. xxv. 
H 2 
