134 Rutherford: Modern 



fluid and negatively when it has a defect or has lost a 

 part of its normal quantity. In addition, Franklin 

 clearly recognized that the charging of a Leyden jar 

 resulted from a disturbance of its electrical equilibrium, 

 which was restored by discharging the jar. 



In a later letter he describes his ingenious investiga- 

 tions to show that the electricity in the jar does not 

 reside in the metal coatings but on the surface of the 

 glass itself, but for our purpose we must be content with 

 only a passing reference to this classical experiment. 



It is hardly necessary to mention here the extraordi- 

 narily wide-spread interest in the work of Franklin that 

 very rapidly followed the publication of his scientific 

 letters. The lucidity of his writings no doubt materially 

 contributed to this result, for in this respect Franklin 

 was in marked contrast to some, of his scientific contem- 

 poraries. Without detracting in the least from the 

 merit of these philosophers, it is not unreasonable to 

 suppose that the turbidity of their writings was a fair 

 index of the state of their conceptions of electrical ac- 

 tions. 



. There has been a tendency in later days among some 

 writers to claim priority for Dufay over Franklin in 

 the conception of the electrical fluid. There appears to 

 be no satisfactory foundation for this belief. Dufay cer- 

 tainly recognized that different kinds of electricity were 

 developed by rubbing glass and resin. This, however. 



