IN THE SOLID AND LIQUID PHASES. JOHNSTONS . 207 



The evidence appears to be conclusive, that at temper- 

 atures above the eutectic, practically all the current passing 

 thru the acid is conducted by the liquid portion of the mixture 

 between the electrodes. So the term, specific resistance of 

 the solid at temperatures above the eutectic is meaningless, 

 and the values obtained for the specific resistance and plotted 

 on curves 1 and 2 merely indicate the resistance of thin columns 

 of the solution of acid and water between the electrodes, 

 multiplied by the cell constant. To obtain a true value for 

 the specific resistance of the solid acetic acid, the temperature 

 must be kept below the eutectic point. 



Comparing the values of the specific resistances in table 

 4, it may be seen that small variations in the quantity of 

 water present greatly affect the specific resistance at temp- 

 eratures above -26.55 in the solid and liquid phases ; while 

 below the eutectic point, the specific resistance is not mater- 

 ially affected by the presence of small quantities of water. 

 At 80C the specific resistance of sample 3 is considerably 

 smaller than that of samples 1 and 2 at the same temperature. 

 This might be expected and it is probably due to the com- 

 paratively large amount of water in the solid form, stretching 

 from one electrode to the other, thus increasing the conduc- 

 tivity of the mixture of ice and acetic acid, as the former has 

 a greater conductivity than the latter. In tubes 1 and 2, the 

 amount of water present is so small, that when frozen, it does 

 not occupy sufficient 'volume to materially affect the sp. 

 resistance. 



Summary. 



1. Three satisfactory methods have been investigated 

 and used in the measurement of high electrolytic resistances. 



2. The specific resistance of acetic acid in the solid and 

 liquid phases, has been measured at temperatures ranging 

 from -80C to 4-27C and sudden changes were found at the 

 melting and eutectic points. 



PKOC. & TRANS. N. S. INST, Sci., VOL. XIII. TRANS. 14. 



