The mirror. (Stillwater, Minn.) 1894-1925, 1899-06-22
ELECTRICITY.
Written for The Prison M M,rrOr,'

! Written for The Prison Mirror
The true nature of electricity is still
unknown. Like the other great forces
| OF nature, it must be studied in the
light of its various manifestations.
Gilbert first employed the term to disig-
nate the phenomena of attraction and
repulsion, which results when amber
electrum and similar substances are
briskly rubbed. Electricity produced
IN this Way-by rubbing together of
certain substances-is termed frac-
tlonal, or static electricity, or Frank
llnlsm, and is rarely used in medicine.
When two dissimilar metals like copper
and zinc are placed in corrosive fluid
and united by loop of wire, the re-
sulting chemical action is attended
with the production of an electric cur
rent, and to this manifestation of elec-
tricity, the term galvanism is applied.
The vessel, its contained fluid, and con-
nected elements together, constitutes a
galvanic cell.
The union of several cells forms
battery. The force which starts the
electric current is termed the electro
motive force, and is always the same in
quantity for the same metals at the
same temperature, and is entirely in
dependent of the size of the plates, their
distance apart, and the character of the
fluid in the cell. The current is gene
rated at the surface of the element or
plate, more easily corroded, which, in
the above illustration, is the zinc, and
passes through the fluid to the element
or plate less affective-that is, the cop
per-and from the external end of the
copper it passes through the wire loop
back again to the external end of the
zinc, thus completing closed circuit.
AS the external end of the copper is
constantly giving off electricity, it is
termed the positive pole, or cathode.
1t is evident, that the electro motive
force will more than represent the
strength of the current, for all SUBJ
stances offer more or less resistance to
the passage of electricity. The resist
ance within the cell is termed the inter-
nal resistance, and that, without the
| cell, the external resistance. The
amount of internal resistance will de-
pend upon the character of the inter-
vening fluid, the size of the plates and
their proximity. The larger the plates
and the closer they are to each other,
the less becomes the internal resistance.
The external resistance depends upon
the length, diameter and character of
the conductor.
The unit of resistance is termed an
ohm. It is about equal to the resistance
offered by copper wire thousand feet
long and one-tenth of an inch in
diameter. The current-strength may
be estimated by the law of ohm. The
strength of an electric current passing
section of the conductor in unit of
time, is proportional to the whole elec-
tro- motive force, and inversely pro.
portional to the sum of all the resistance
in the circuit.
The unit of electro. motive force is
the volt. 1t is the amount of electricity
required to overcome an ohm of re-
sistance.
The unit of current-strength is the
ampere, but as this is too large unit
for medicinal purposes, one thousand
of an ampere, or milliampire, is en-
ployed instead. The current-strength
of battery can be increased in three
ways:
1. By diminishing the external re-
sistance.
2. By diminishing the internal re-
sistance.
3. By increasing the number of cells.
When the external resistance is
fixed quantity, which is often the case,
the current.strength can still be in