Electropoion Fluid.
An acid depolarizing solution for use in zinc-carbon couples, such as
the Grenet battery. The following are formulae for its preparation:
(a) Dissolve one pound of potassium bichromate in ten pounds of water,
to which two and one-half pounds of concentrated sulphuric acid have
been gradually added. The better way is to use powdered potassium
bichromate, add it to the water first, and then gradually add the
sulphuric acid with constant stirring.
(b) To three pints of water add five fluid ounces of concentrated
sulphuric acid; add six ounces pulverized potassium bichromate.
(c) Mix one gallon concentrated sulphuric acid and three gallons of
water. In a separate vessel dissolve six pounds potassium bichromate in
two gallons of boiling water. Mix the two.
The last is the best formula. Always use electropoion fluid cold. (See
Trouvé's Solution--Poggendorff's Solution--Kakogey's Solution--
Tissandrier's Solution--Chutaux's Solution.)
Electro-positive. adj.
Appertaining to positive electrification; thus potassium is the most
electro-positive of the elements. (See Electro-negative.)
Electro-puncture.
The introduction into the system of a platinum point or needle,
insulated with vulcanite, except near its point, and connected as the
anode of a galvanic battery. The kathode is a metal one, covered with a
wet sponge and applied on the surface near the place of puncture. It is
used for treatment of aneurisms or diseased growths, and also for
removal of hair by electrolysis. (See Hair, Removal of by Electrolysis.)
Synonym--Galvano-puncture.
Electro-receptive. adj.
A term applied to any device or apparatus designed to receive and absorb
electric energy. A motor is an example of an electro-receptive
mechanism.
Electroscope.
An apparatus for indicating the presence of an electric charge, and also
for determining the sign, or whether the charge is positive or negative.
The simplest form consists of a thread doubled at its centre and hung
therefrom. On being charged, or on being connected to a charged body the
threads diverge. A pair of pith balls may be suspended in a similar way,
or a couple of strips of gold leaf within a flask (the gold leaf
electroscope). To use an electroscope to determine the sign of the
charge it is first slightly charged. The body to be tested is then
applied to the point of suspension, or other charging point. If at once
further repelled the charge of the body is of the same sign as the
slight charge first imparted to the electroscope leaves; the leaves as
they become more excited will at once diverge more. If of different sign
they will at first approach as their charge is neutralized and will
afterwards diverge.
The gold-leaf electroscope is generally enclosed in a glass bell jar or
flask. Sometimes a pair of posts rise, one on each side, to supply
points of induction from the earth to intensify the action. (See
Electrometer, Quadrant--Electroscope, Gold leaf, and others.)