ELECTRIC DISCHARGE WITH THE CHLORIDE OF SILVER BATTERY. 
05 
Length of wire, 
miles. 
Diam. of wire, 
inches. 
Resistance. 
ohms. 
Turns. 
Layers. 
Primary 
1 
•014 
316 
12,958 
31 
Secondary . 
.4 
•0033 
19,355 
18,260 
22 
This we call a detector-coil, it being used to render evident pulsations in the current, 
and it will be referred to hereafter. The secondary wire of the coil is led to a delicate 
Thomson galvanometer. 
All these pieces of apparatus can be plugged out of circuit, wheu not required, in a 
few seconds, and each battery can be as readily brought into or thrown out of action 
without inconvenience or danger to the operator. Not without fear of being prolix, it 
has appeared to us desirable to commence by giving the preceding details, as it will 
facilitate the understanding of the varied experiments we have to describe hereinafter. 
We will commence with — 
1st. Discharge at ordinary Atmospheric Pressures. 
The discharge from a point presents many interesting features, which do not 
occur with other shaped terminals, which we will describe later on, page 88, and at once 
proceed to the discharge from spherical surfaces, first premising that we have found 
that the nature of the metal employed for terminals in most cases makes no difference 
whatever in the length of the spark ( distance explosive) of the battery. Whatever 
may be the theory of the electric discharge, our experiments show that with the same 
terminals and the same number of cells the results have a remarkable constancy, 
notwithstanding the length of the interval between the experiments, and the 
consequently varying internal resistance of the battery from the gradual formation 
of the skin of oxychloride of zinc before referred to, and hereinafter to be 
specially discussed. The length of the spark evidently depends essentially on 
the number of cells and their electro-motive force. The spherical surfaces we have 
employed are of brass, 1’5 inch in diameter and having a radius of 3 inches. The 
discharging-micrometer (fig. 1) does not permit larger terminals to be used, but there 
is no reason to suppose that their diameter materially affects the results, because we 
found that spherical surfaces smaller in diameter gave nearly the same numbers. In 
evidence of the constancy of the results, we give the following numbers, some of which 
will be dealt with in deducing the length of spark for a given number of volts. 
MDCCCLXXVill. 
K 
