CHAPTER XII. =Miscellaneous Experiments= 81 Exp. 96, To show that friction always produces two kinds of electrification.--Discussion.--Exp. 97, To show "successive sparks."--Exp. 98, To show to the eye the strong attraction between a charged and a neutral body.--Exp. 99, To feel the strong attraction between a charged and a neutral body.--Exp. 100, The human body a frictional electric machine.--Static Electric Machines. CHAPTER XIII. =Atmospheric Electricity= 84 Atmospheric Electricity.--Lightning.--Thunder.--Lightning Rods.--Causes of Atmospheric Electricity.--St. Elmo's Fire.--Aurora Borealis. PART III.--CURRENT ELECTRICITY. CHAPTER XIV. CONSTRUCTION AND USE OF APPARATUS 89 Exp. 101, To study the effect of the electric current upon the magnetic needle.--Electrical Connections.--Current Detectors.--Exp. 102, To study the construction and use of a simple "key."--Exp. 103, To study the construction and use of a simple "current reverser."--Exp. 104, To study the simple current detector.--Exp. 105, To study the construction and use of the simple galvanoscope.--Discussion; True Readings.--Exp. 106, To study the construction and use of a simple astatic needle.--Astatic Needles.--Exp. 107, To study the construction and use of a simple astatic galvanoscope.--Astatic Galvanoscopes. 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."