CONTENTS OP VOLUME II, 



[NOTE. For Analytical Index, see first Volume.] 



MATTER AND ITS PHYSICAL PROPERTIES PAGE 17 



Divisibility. Unlimited Divisibility. Wollaston's Micrometric Wire. Method of Making it. 

 Thiclfcess of a Soap-Babble. Wings of Insects. Gilding of Embroidery. Globules of the 

 Blood. Animalcules. Their minute Organization. Ultimate Atoms. Crystals. Porosity. Vol- 

 ume. Density. Quicksilver passing through Pores of Wood. Filtration. Porosity of Hydro- 

 phane. Compressibility. Elasticity. Dilatability. Heat. Contraction of Metal used to restore 

 tlie Perpendicular to Walls of a Building. Impenetrability of Air. Compressibility of it. Elas- 

 ticity of it. Liquidsnot absolutely Incompressible. Experiments. Elasticity of Fluids. Aeriform 

 Fluids. Domestic Fire-Box. Evolution of Heat by compressed Air. Inertia. Matter incapable 

 of spontaneous Change. Impediments to Motion. Motion of the Solar System. Law of Nature. 

 Spontaneous Motion. Immateriality of the thinking and willing Principles. Language used to 

 express Inertia sometimes faulty. Familiar Examples of Inertia. 



ELASTICITY OF AIR 39 



Exhausting Syringe. Rate of Exhaustion. Impossible to produce a perfect Vacuum. Mechanical 

 Defects. The Air-Pump. Barometer-Gauge. Siphon-Gauge. Various Forms of Air-Pump. 

 Pump without Suction- Valve. Experiments with Air-Pump. Bladder burst by atmospheric 

 Pressure. Bladder burst by Elasticity of Air. Dried Fruit inflated by fixed Air. Flaccid Blad- 

 der swells by Expansion. Water raised by Elastic Force. A Pump cannot act in the Absence 

 of atmospheric Pressure. Suction ceases when this Pressure is removed. The Magdeburg Hem- 

 isphere. Guinea and Feather Experiment. Cupping. Effervescing Liquors. Sparkling of 

 Champagne, &c. Presence of Air necessary for the Transmission of Sound. The condensing 

 Syringe. The Couderi&er. 



EFFECTS OF LIGHTNING... 61 



Classification of the Effects of Lightning. The sulphureous Odor leveloped by Lightning. Cases 

 collected by M. Arago. Nature of the Odor. Chemical Changes operated by Lightning. Nitric 

 Acid formed by the Electric Spark; also Ammonia and Nitric Acid produced during Thunder- 

 Storms. Fusion and Contraction of Metals. Observations of the Ancients. Franklin's cold 

 Fusion. Evidence against cold Fusion. Masses of Metal melted by Lightning. Vitrcjactions 

 and Fulgurites. Heights at which Vitrefactions have been found. Facts collected by M. Arago. 

 Fulminary Tubes, or Fulgurites. Characters of Fulgurites. Variations dependent on the Na- 

 ture of the Soil where they are found. Four Hypotheses to explain their Origin. Their Forma- 

 tions in some Cases are recent. Sand fused by artificial Heat into the State of the Fulgurites. 

 Artificial Fulgurites formed by the Electrical Battery. The further Condition essential to explain 

 the Origin of Fulgurites. Recent Formation of Fulgurites observed. Mechanical Ejects. In- 

 stances of the Mechanical Action of Lightning. The Action is exerted in all Directions. Induc- 

 tive Action of Lightning. M. Arago's Explanation of the Effect as due to Vaporization. Objec- 

 tions to the Explanation. Decompositions of the natural Electricities of Bodies. Induction 

 between the Clouds and the Earth. Upwar 1 Flashes and Mechanical Effects. Arago's Explana- 

 tion. Magnetic Effects. To be explained in ELECTRO-MAGNETISM. Effects of conducting Bodies 

 on Lightning.- Conducting Properties of Metallic Bodies. Lightning passing along Conductors 

 in Preference to Non-Conductors. Protection afforded by conducting Bodies. Lightning se'ects 

 conducting Bodies from among others. Lightning Conductors should descend to a humid Soil. 



