118 Profs. W. E. Ayrtoii and J. Perry on 



Afterwards electromotive force increased to 87 volts. First a 



great swing off the scale, then returned 



[, and in about one 



minute — that is, at 







h m s 



Deflection. 



Temperature. 



8 12 



212-7 



-12°-85 0. 



8 15 



145-7 





9 12 



66-2 



-10°-8 C. 



9 17 



65-2 





9 58 30 



Q>^'2 



- 8°-85 C. 



Comparing the observation at 8^ 12°" 0^ with that taken at 

 gh gra Qa^ ^y^ ggg ^j^jj^^ ^jjg dcflections are nearly proportional to 

 the electromotive forces employed ; this, however, is not the 

 case in the other instances when the electromotive force was 

 increased. The object of giving three or four time-observa- 

 tions for each electromotive force in the above Table is for the 

 purpose of showing with what rapidity the reading was 

 chano-inoj in each case. 



IV. Fehriiary 11. — A very consistent series of observations 

 was made. We first tried the effect of varying the time of 

 charging when measuring the discharge from the arrange- 

 ment as a condenser ; and we found that increasing the time 

 of charging increased the discharge, the temperature of the 

 distilled water in the copper box being 8°-7 C. Charging, 

 however, for ten seconds with an electromotive force of 0*174 

 volt, and discharging through the galvanometer when shunted 

 with the one-thousandth shunt, and leaving the copper disk and 

 box short-circuited for fifteen seconds after each discharge, we 

 obtained, during many successive trials, swings varying be- 

 tween 75 and 81, and having a mean value of 79. This cor- 

 responded with a capacity for the water of 1881 microfarads, 

 or 4-384 microfarads per cubic centimetre, making the specific 

 inductive capacity of water 50 x 10^, that of air being called 

 unity. Of course this number is rather too low, as no allow- 

 ance is made for the loss of charp-e that must occur in the 

 very short interval between the conclusion of the charging 

 and the commencement of the discharge. The current pro- 

 duced by an electromotive force of 0-174 volt was now passed 

 through the water, and the fall of current measured as the 

 temperature was lowered. This diminution of current was 

 partly due to polarization, but more due to increase of resist- 

 ance by diminution of temperature. It was quite evident that 

 this increase of resistance was very great, and that it was 

 quite regular in the passage from the liquid to the solid state. 

 These observations we do not give ; it is sufficient to state that 

 they were consistent with the more important subsequent ob- 



