506 



Dr. E. J. Mills on Electro striction. [Dec. 13, 



its equatorial, and much less on the polar regions. The registered rise 

 was the height of the mercury in melting ice. After the twenty-second 

 hour, and as soon as the scale had been read with the kathetometer, the 

 mercury rose spontaneously 0-16 of a unit. The subsequent observations 

 are accordingly lessened by this amount. The equation is— 



2/= 9-728 (-87074)*-4-979 (-83117)*. 



Table II. 



X. 



v. 



y calc. 



Temp. 



1 



4-613 



4-332 







16-2 



2 



3-996 



3-936 



16-6 



3 



3-556 



3-563 



16-8 



4 



3-270 



3-216 



15-7 



5 



2-941 



2-894 



16-5 



7 



2-321 



2-328 



15-5 



9 



1-815 



1-856 



14-7 



11 



1-462 



1-471 



12-7 



13 



1-242 



1-159 



15-7 



15 



0-973 



0-909 



16-3 



17 



0-708 



0-710 



17-2 



19 



0-553 



0-553 



17-2 



21 



0-475 



0-430 



15-2 



23 



0-335 



0-332 



16-5 



25 



0-251 



0-257 



14-5 



Mean temperature 15*8 

 The above values of x are convertible into hours by multiplying by 2. 



The probable error of a single comparison of theory with experiment is 

 •057. After the fiftieth hour the operation was left unattended for 28 

 hours, when an additional rise of -25 was found to have taken place. 



On other occasions an ascent of 12-87 was obtained, with thermometer 

 454, in twenty-four hours, the thickness of the deposit being approxi- 

 mately '29 millimetre. An ascent of 11-50 was also observed with ther- 

 mometer 455, the thickness of metal being probably not less than a mil- 

 limetre. The zero of thermometers was found to be nearly the same after 

 electrostriction and stripping as at first ; it had not risen more than 

 0°-03. 



Silver. — Thermometer 454, slightly coated with silver by electro-depo- 

 sition, was used in the following experiments : the coating was first 

 sand-papered and polished. Observations were made and the thermo- 

 meter semirotated every half-hour until the fifth hour ; the electrolyte 

 was not stirred between the fifth and twenty-third hours, but after this 

 interval the ordinary course of observations was resumed. The equa- 

 tion is — 



