348 ATMOSPHERIC ELECTRICITY. 



tional to the sum of the partial forces, without there being any re- 

 markable discharges. It will produce only the effects of static elec- 

 tricity, those of attraction or repulsion, and those of simple radiation. 

 If, on thu contrary, the particles of vapor are sufficiently near for their 

 electric spheres to penetrate each other, or if the repulsion of the 

 electrical spheres act more strongly than the bond which unites 

 them to the vapor, all the internal particles will lose a portion of 

 their electricity in favor of the extreme particles ; there will then be 

 formed around the exterior of the cloudy mass a stratum of free elec- 

 tricity such as is usually formed around an ordinary conductor." 



Thus, according to M. Peltier^ the clouds have two kinds of tension; 

 the tension of free electricity at the surface, and that of the electricity 

 retained around each of the moleculs of its vapor. From this M. 

 Peltier sought to explain how vapor could form limited masses, 

 notwithstanding the mutual repulsion of the particles, owing to the 

 electric tension of the latter. The tension of the particles repels them 

 and keeps them at a distance, while the electricity of the surface 

 attracts them, groups them, and retains them in mass, everywhere 

 leaving to each its individuality, if the exterior tension is moderate 

 and proportional to that of the interior. M. Peltier has demonstrated 

 this repulsive and condensing action from the exterior to the interior, 

 by the following experiment: He isolated a glass funnel, the tube of 

 which was one or two millimeters in diameter, and filled it with water, 

 communicating by means of a conductor with an electric machine. 

 By allowing the water to escape under the influence of the electricity 

 furnished by the latter it falls, as we know in rain more or less fine, 

 according to the electric charge which is given to it. But if a copper 

 tube of the height of 5 to ten centimetres and of a diameter nearly 

 equal be placed a little below the orifice of escape, and if it be charged 

 with the same electricity as the water, instantly the drops of the 

 latter will approach and unite together in a single stream. This 

 experiment is rendered more complete by making use of a metallic insu- 

 lated globe, the diameter of which is pierced with two holes to let in a 

 ray of light. The water of the funnel being electrified falls into 

 the globe in a divergent cone. The globe gradually becomes electrified 

 and reacts on the streams which approach and unite until there is 

 an equilibrium of reaction between the interior repulsion and that of 

 the exterior. If the globe communicates with the electrical machine, 

 the powerful tension immediately reunites the divergent streams into a 

 single one as in the experiment of the tube. 



The electricit}^ which surrounds a cloud could not therefore be formed 

 of all the electricity which it contains, as that of a metal conductor 

 which retains no portion in its interior ; it would be, on the contrary, 

 only a feeble portion dependent on interior reaction and conductibility. 

 This theory simplifies and facilitates the interpretation of many phe- 

 nomena which take place during storms; it would be important to 

 see it confirmed by direct observations, which might be possible by 

 studying, especially in mountainous countries with the help of kites 

 sustained by conducting wires, the electrical modifications of the dif- 

 ferent parts of a cloud. M. Peltier* found in the two kinds of elec- 



-- Journal I'Institut, No. 335 and No. 370. 



