322 Profs. J. A. Fleming and J. Dewar. On the Dielectric 



Temperature, 



Dielectric constant of 



Centigrade. 



water (Thwing). 



AO 



HA. i ft 



79*46 



o 



Li 







8^-90, 



fi 

 D 



Ov o^b 



7 





Q 



77-OA 



1 9 



7fv90 



±D 



7*^0 

 # O Ov 





7Q-Q9 



97 



79-70, 





oy ou 



65 



6432 



80 



60-50 



88 



57-90 



L. Drude (* Wied. Ann.,' vol. 59, pp. 17 — 68) using electric -waves 

 74 cm. in wave-length, determined the electric refractive index of 

 water for various temperatures. Also Heerwagen (' Wied. Aim.,' 

 vol.49, 1893, p. 278) made similar determinations, using, however, a 

 slow speed method. The results of the two last observers are given 

 for comparison in the following table : — 



Dielectric constant of water. 



Temperature, 

 Centigrade. 



0-2° 



(Drude.) 



87-3 



. ^ 



(Heerwagen.) 



86-96 



41 



86-02 



85-55 



7-9 



84-49 



84-17 



11-6 



83-41 



82-83 



11-9 



81-20 



80-90 



25-8 



77-99 



77-70 



379 



73-44 



72-67 



45-4 



71-28 



70-60 



49-8 



70-01 



69-C0 



54-8 



68-60 



6721 



59-7 



67-17 



66-02 



66-0 



66-02 



63-14 



70-1 



64-83 



61-66 



72-8 



63-68 



60-66 



76-3 



62-82 



59-41 



Drude and Heerwagen do not agree with Thwing in making the 

 dielectric constant of water a maximum at 4° C, but they all agree 

 that an increase of temperature decreases the dielectric constant of 

 water beyond that point. As we find an enormous decrease in the 



