On the Leakage of Electricity from Charged Bodies. 97 



V. Condensational -Rare/ 'actional Wave at the Interface of a 

 Fluid and an Elastic Solid ; incident in the Fluid. 



We get the solution from the general case by putting 

 B t = 0, n = 0, 7= co, and 



^-'K^V-i)^*!), 



and the result is 



cY = B'+ c'A! 



whence 



^,( 7 ' 2 +l)X = 2 7 'B'+( 7 '-'-l)A' }; 



P 



= ( 7 ' 2 -l)B'- 2ck! 



B' = 



2c' 



A' 



Y -- 



X 



c' 7 ' 2 +l 



c 7 /2 -L 

 - o W*-l 



A' 



+ 



7 /2 -l 

 7 ' 2 +l 



) A ' 



(4") 



.(5") 



IV. Leakage of Electricity from Charged Bodies at Moderate 

 Temperatures. By J. 0. Beattie, Z>.3c, F.R.S.E., Pro- 

 fessor of Applied Mathematics and Physics, South African 

 College, Cape Toivn*. 



§ 1. rPHE conditions in which a charged body retains its 

 _JL charge have been investigated with great thorough- 

 ness in many directions. The effect of heat, of light, of 

 Bontgen rays, of uranium rays on the insulation ; the effect 

 of the nature of the charged body; the effect of the surround- 

 ing atmosphere — its constitution and pressure; the effect of 

 fumes from flames, have been made the subject of experiment. 

 In quite recent years the subject has also been investigated 

 from the point of view of what becomes of the electricity 

 which leaks away from an insulated body in certain con- 

 ditions. The object of the present series of papers is to 

 communicate a number of results obtained by the writer on 

 the leakage of electricity from metallic plates covered with 

 various substances when the plates were placed in an atmo- 



* Communicated by Lord Kelvin, having been read before the Royal 

 Society of Edinburgh, May 1, 1899. 



Phd. Mag. S. 5. Vol. 4.8. Ko. 290. July 1899. H 



