[ 40 ] 



III. 



ELECTRIFICATION BY FEICTION. 

 l'.v PROFESSOR J. A. M. CLELLAND, D.Sc, F.R.S., 



AND 



REV. C. -I. POWER, S.J. M.Sc. 



Read Fbbiiuahy 11. Published Ai-mi. 17, 1918. 



The work described in this paper may be looked upon as an attempt to study 

 friclional electricity in an accurate and quantitative manner. 



It has been found possible to overcome the well-known experimental 

 difficulties of the subject to a sufficient extent t" enable consistent results 

 to be obtained. We ha\v studied tin- of dill'erent .pressures between 



the rubbing surfaces, different relative motions, changes of temperature and 

 ..i the amount of moisture in the air, and finally «r have carried out 

 experiments in gat gTeatlj reduced pressures. 



None of these subjects has been examined fully; we have in the first 



e made a general survey of some of the different factors which influence 

 the rate of production of frictional electricity, with the object of deciding on 

 the points most likely to repay fuller investigation. 



The work described in this paper was carried out two years ;,._',., Inn 

 pressure of other work caused an interruption, and it was only recently that it 



has I ii possible to take up the detailed study of son f the point- touched 



on in tin- pa] 



Work on frictional electricity has been published in recent years by 

 M vis Owen,' Morris Jones," 1 ench,' and Shaw, 4 but there is nol much 

 direct overlapping in the case of our work with that of these authors. 



Apparatus. 



Art' i Beveral attempt- along different lines the following method of 

 producing friction between surfaces was found to give satisfactory results. 



■ Phil. Mag., Feb., 1915. 

 1 rencb, Physical Review, vol. i\. IS .'. Feb. 1 r » l T - 

 ' si, . P I P P 3oi , vol wvii. \|.nl. 1915 ; Proc. Roy. Soc., vol. xciv, 



T.'IT 



