On the Ionizing Power of Solvents. 



Per cent, of water 



Cell. 



Resistance 



Conductivity in 



by weight. 



at 18°. 



C.G.S. units. 



2-47 



2 



228 



3-675 Xl0~ 13 



3-41 





185 



5-Hl „ 



433 





160 



6304 „ 



611 



}J 



118 



9435 „ 



1107 





68 



1854 „ 



18-28 





40-4 



32-76 „ 



2967 



1 



423 



51-99 



4501 





285 



78-41 



61-71 



,, 



226 



99-48 



78-23 





231 



97-31 



84-79 





260 



8617 



9051 





315 



70-69 „ 



97-70 







39-50 „ 



9943 







19-38 „ 



The numbers below the dotted line are calculated from Ostwald's 

 results for solutions of formic acid in water. 



If we plot these results as curves, showing the relation 

 between the percentage of water and the electrical con- 

 ductivity, we get the diagrams represented in figs. 3, 4, 

 and 5. It must be noticed that these curves are not 

 drawn on the same vertical scale. The ascending branch 

 of each curve relates to a solution of water in the acid, 

 while the descending branch is concerned with a solution of 

 the acid in water. These latter solutions all give curves of 

 the same general form, asymptotic to the vertical axis, and 

 this may be considered as the typical curve of a conducting 

 solution. The actual conductivity has not much influence on 

 the general form of the curve, though it will, of course, alter 

 its constants. This is shown by the fact that the general 

 form of the curve for acetic acid in water is the same as that 

 for trichloracetic acid, which has a very much higher con- 

 ductivity. The general form of the curve may thus be con- 

 sidered to be determined by the general electrical nature of 

 the liquid, about which it will therefore give us valuable 

 information. 



Let us now examine the ascending portions of the curves, 

 which relate to mixtures containing small percentages of 

 water, that is, to solutions of water in the acids. In the 

 cases of acetic and trichloracetic acids, which are liquids with 

 dielectric constants very small as compared with that of 

 water, the form of the upward curve is entirely different 

 from that of the descending branch. Instead of approaching 

 the vertical axis asymptotically, it approaches the horizontal 

 axis in this manner, and eventually cuts the vertical axis at 

 right angles. 



