of Organic Bodies, <£•<?., at very Low Temperatures. 255 



the bridge measurement made, and the reading S or the change of 

 capacity of the sliding condenser observed, as before, when the 

 experimental condenser had its position changed. 



The following Table IV gives the summary of the results obtained 

 with several substances at various temperatures. 



Table IV. — Measurement of the Dielectric Constants of various 



Substances at different Temperatures by Nernst's Method. Fre- 



quency = 320. 



S = 



1-50, = 5 27. 













> — s 















Calculated 



Temperature 



Substance. 









dielectric 



in platinum 



S. 



S-s. 



5'27(S — s). constant = D, 



decrees. 



Ethylic ether. . 



2-1 



0-6 



3-16 



4-16 



+ 15° 





12-15 



10-65 



56-2 



57-2 



+ 30 



Solution of am- 



r 4-5 



3-0 



15-8 



16-8 



-123 (?) 



monia (sp. gr. < 



5-6 



4-1 



21-6 



22-6 



-137 



= 0-880).... 



1 135 



12-0 



63-0 



64-0 



-119 



Distilled water 



r 0-2 



0-5 



2-6 



3-6 



-49 



11-0 



9-5 



50-0 



51-0 



-7 



or pure ice . . 



114-3 



12-8 



67-0 



68-0 



+ 1 



Oxide of copper "1 



3-95 



2-45 



12-9 



13-9 



-61 



in suspension / 



'l2-8 



11-3 



59-7 



60-7 



-41 



in water . . . . J 









The value found for the dielectric constant of water at 4-1° is 

 rather low, but, as above mentioned, the smallness of the capacity of 

 the experimental condenser prevented the results from being more 

 than good indications of the order of the dielectric constant. 



We have, in addition, repeated and extended experiments made 

 with the cone condenser on various electrolytes and dielectrics. 



In the first place, we have carefully examined the effect of change 

 of temperature on the dimensions of the cone condenser per se to 

 ascertain if the dimensional change produced by cooling it in liquid 

 air could sensibly affect the value of the dielectric constant of an 

 electrolyte forming the dielectric between the cones, apart from the 

 change which temperature produces in the dielectric quality of the 

 dielectric itself. 



The gilt cone condenser was accordingly connected with the 

 tuning-fork interrupter as formerly described,* and the galvano- 

 meter scale deflection when the condenser was charged with 97 "2 volts 

 was found to be 3'85 cm. to the left and 3'88 cm. to the right, hence 

 the mean galvanometer deflection was 3'87 cm. of the scale. This 

 corrected to 100 volts becomes 3*98, and deducting 0'4 cm. for the 

 capacity of the leads, gives 3*58 as the number representing the 

 * See Fleming and Dewar, 'Key. Soc, Proc.,' vol. 61, 1897, p. 299. 



