METEOROLOGY. oGj 



coDdensation of steam as a cause of electrification, and finds wholly neg- 

 ative results. {Nature, xxix, p. 227.) 



338. G. Le Goarant de Tromelin publishes in the Comptes Eendus 

 of Paris his theory that the principal cause of atmospheric electricity 

 consists in the friction of moist masses of air on the surface of the earth 

 or ocean. The electrified molecules of water rise above and form clouds 

 on whose surface the electricity is expanded, which then gives occasion 

 to lightning; during the afternoon and evening the water, vapor, and 

 clouds, cool down, the electric tension on the individual particles of mist 

 becomes greater, and the electric discharges known as heat-lightning 

 occur. [Paris, Comptes Bendus, 1884, p. 248.) 



339. Dr. Linns, of Darmstadt, in reference to the origin of atmos- 

 pheric electricity, suggests a laboratory experiment which he thinks is 

 new and will go far to elucidate his view of the subject, according to 

 which the electricity of the rain and thunder clouds can only affect the 

 instruments, and give the phenomena of high tension, through the sepa- 

 ration in space of the two principal parts of the cloud, namely, the air 

 and the vapor. The three fundamental questions are the following: (1) 

 whether electricity is first formed during the fall of the precipitation 

 possibly through its friction on the air, or (2) whether it is produced by 

 the process of condensation itself, or (3) whether before the precipitation, 

 in the mixture of air and vapor, the molecules of these components are 

 not laden with the opposite electricities. Linns considers the latter as 

 the most plausible, in view of our present knowledge of electricity, 

 that in fact the electricity of the clouds results from the well-known 

 phejiomena of contact electricity observed in the contact of hetero- 

 genous bodies; the molecules of the components of a mixture of gases 

 are, in consequence of the enormous number of impacts which, accord- 

 ing to the latest theory, occurs in every second, oppositely electrified by 

 contact ; this electricity, however, can only produce an exterior effect 

 through a rapid separation of the gases ; the original mixture itself 

 must always appear uon electric on account of the intimate mixture of 

 the oppositely electritied molecules, and since the sum of the positive 

 and negative electricities must be equal to each other. His proposed 

 experiment looks to the rapid separation of the vapor and gas by ab- 

 sorption, and the experiment should succeed with other gases and vapors 

 besides those of the atmosphere. 



340. Dr. E. Hoppe, of Hamburg, having opposed this hypothesis from 

 a theoretir'al point of view, Dr. Linns replies suggesting other experi- 

 ments, and also states that he has now, since August, 1883, conducted 

 observations on the loss or dissipation of electricity by conductors ex- 

 posed to free atmosphere ; he finds the loss least in winter, greatest in 

 summer, less in the morning and evening, greater in the day time. He 

 proposes that lines of equal electric loss be constructed on the daily 

 weather charts, by the study of which our knowledge of atmospheric 

 electricity will be much assisted. {D. M. Z,, i, j). 4G4.) 



