70 Intelligence and Miscellaneous Articles. 



an equivalent loss of vis viva necessarily corresponds ; and that is 

 the reason why the waves must quickly lose their force as soon as 

 they come into contact with an oily layer. 



Such are the very simple propositions which permit me to account 

 for a phenomenon known from ancient times, but which, even on 

 account of its singularity, has not yet obtained the valuable appli- 

 cations it deserves. — Comptes Renclus de VAcademie des Sciences, 

 Nov. 27, 1882, t. xcv. pp. 1055, 1056. 



ON THE ELECTRIFICATION OF THE AIR. BY M. MASCART. 



At one of the meetings of the International Committee for the 

 determination of the electric units, lately assembled at Paris, Sir 

 W. Thomson pointed out the importance to science of continuous 

 observations of the proper electrification of the lower strata of the 

 atmosphere by determiuing the potential in a limited volume of gas 

 taken from the surrounding air and withdrawn from the action of 

 foreign electrical masses. 



I have essayed to see by experiment how a mass of air thus iso- 

 lated preserves its electrification, in order to define the conditions 

 under which it would be expedient to place one's self for the par- 

 pose of continuous observation. 



The air of the amphitheatre of the College de France, which 

 represents, roughly, a cube of 9 or 10 metres side, was electrified 

 by discharging into it a Ley den jar during 10 seconds by a conduct- 

 ing flame. An electrometer, placed in the room, was in communi- 

 cation with a receiving flame placed about 8 metres from the spot 

 where the discharge took place, and 1*5 metre from the ground. 

 As soon as the discharge is commenced the electrometer is affected : 

 the deflection at first undergoes a series of oscillations of great am- 

 plitude, then increases in a more regular manner, reaches a maxi- 

 mum at the end of from 10 to 15 minutes, and afterwards decreases 

 very slowly. 



The larger oscillations at the outset appeared to result from a 

 direct action of the electrified strata of air upon the conducting 

 wires of the electrometer, which were too near them. To eliminate 

 this cause of error, the electrometer was placed in an adjacent room, 

 the communication with the receiving flame being established by a 

 wire passing through the partition. In this case the effects are 

 more regular : the maximum deflection was again reached in about 

 a quarter of an hour ; it then diminished slowly, obeying a law 

 clearly indicated by the form of the curve to be an exponential, 

 like that for thermal radiation. After tw 7 o hours the potential was 

 still -^\ of its maximum value. Nevertheless there was still mani- 

 fested, especially during the first minutes, a series of oscillations 

 of small amplitude ; and those oscillations were exaggerated as soon 

 as a door was opened even for a very short time, or if an observer 

 crossed the room at several metres distance from the receiving 

 flame. 



These phenomena can be naturally explained if it be admitted 



