Chapter XV: Galvanic Cells and Batteries 102

Exp. 108, To study the effect of dilute sulphuric acid
upon carbon and various metals.--To amalgamate.--Dilute
sulphuric acid.--Discussion.--Exp. 109, To study the effect
of dilute sulphuric acid upon various combinations of
metals.--Discussion.--Exp. 110, To study the construction of a
simple Voltaic or Galvanic cell.--The Electric Current.--Source
of the Electrification.--The Electric Circuit; Open and Closed
Circuits.--Plates or Elements.--Direction of Current.--Poles or
Electrodes.--Chemical Action in the Simple Galvanic Cell.--Action
in Cell Using Impure Zinc; Action Using Pure Zinc.--Exp. 111, To
see what is meant by "local currents" in the cell.--Local Action;
Local Currents.--Reasons for Amalgamating Zinc Plates.--Exp.
112, To study the "single-fluid" Galvanic Cell.--The Simple
Cell.--Polarization of Cells.--Effects of Polarization.--Remedies
for Polarization; Depolarizers.--Exp. 113, To study the
"two-fluid" Galvanic Cell.--Setting Up the Two-Fluid Cell.--Care
of Two-Fluid Cell.--Copper Sulphate Solution.--Chemical Action
in the Two-Fluid Cell.--Various Galvanic Cells; Open and Closed
Circuit Cells.--The Leclanché Cell--Dry Cells.--The Bichromate of
Potash Cell.--The Daniell Cell.--The Gravity Cell.

CHAPTER XVI. THE ELECTRIC CIRCUIT 115

Exp. 114, To see what is meant by "divided circuits" and
"shunts."--Divided Circuits; Shunts.--Exp. 115, To see what is
meant by "short circuits."

CHAPTER XVII. ELECTROMOTIVE FORCE 117

Electromotive Force.--Unit of E. M. F.; The Volt.--Exp.
116, To see whether the E. M. F. of a cell depends upon the
materials used in its construction.--Discussion.--Electromotive
Series.--Exp. 117, To see whether the E. M. F. of a cell depends
upon its size.--Discussion.

CHAPTER XVIII. ELECTRICAL RESISTANCE 120

Resistance.--Exp. 118, To study the general effect of
"resistance" upon a current.--External Resistance; Internal
Resistance; Unit of Resistance; The Ohm.--Resistance Coils;
Resistance Boxes.--Simple Resistance Coil.--Exp. 119, To
test the power of various substances to conduct galvanic
electricity.--Conductors and Nonconductors.--Exp. 120, To
find the effect of sulphuric acid upon the conductivity
of water.--Internal Resistance.--Exp. 121, To find what
effect the length of a wire has upon its electrical
resistance.--Discussion.--Exp. 122, To find what effect the
size (area of cross-section) of a wire has upon its electrical
resistance.--Discussion.--Exp. 123, To compare the resistance of
a divided circuit with the resistance of one of its branches.
Discussion.--Exp. 124, To study the effect of decreasing the
resistance in one branch of a divided circuit.--Current in
Divided Circuits.

CHAPTER XIX. MEASUREMENT OF RESISTANCE 130

Exp. 125, To study the construction and use of a simple
Wheatstone's Bridge.--The Simple Bridge.--Equipotential
Points.--Example.--Exp. 126, To measure the resistance of a wire
by means of Wheatstone's Bridge; the "bridge method."--Allowances
for Connections.--Exps. 127-137, To measure the resistances of
various wires, coils, etc., by the "bridge method."--Table.--Exp.
138, To study the effect of heat upon the resistance of
metals.--Effect of Heat upon Resistance.--Exp. 139, To measure
the resistance of a wire by the "method of substitution."--Simple
Rheostat.--Exp. 140, To measure the E. M. F. of a cell by
comparison with the two-fluid cell.--Exp. 141, To measure the
internal resistance of a cell by the "method of opposition."