EFFECTS OF LIGHTNING. 



Classification of the Effects of Lightning. The sulphureous Odor developed by Lightning. C&#* 

 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. Vitref actions 

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

 Fulminary Tubes, or Fulgurites. Characters of Fulgurites. Variations dependant 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 Effects. 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 be- 

 tween the Clouds and the Earth. Upward 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 Con- 

 ductors in Preference to Non-Conductors. Protection afforded by conducting Bodies. Lightning 

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

 SoD. Necessity of Continuity in a Conductor. Effects proceeding from the Surface of the Earth. j 

 Ascent or Ebulition of Water. Inundations from subterranean Sources. Mosaic Account of the i 

 Deluge; Analogous natural Phenomena. Electrical State of the Atmosphere Favorable to the | 

 Process of barking Trees. Effect of Thunder on fermented Liquors, &c. B/eturn Stroke report- < 

 ed by Brydone. Theory of such Effects. Flame appearing on the Ground. Not extinguisha- ( 

 ble by Water. Superposed Clouds not necessary to its Appearance. Stationary luminous Ap- j 

 pearance. Lightning rising from the Earth like a Rocket Flames observed on exposed Points. S 

 Luimnous Rain. Cases collected by M. Arago. Luminous Dust 



