[BARNES & JOHNSON] FALL OF ‘POTENTIAL METHOD 139 
On the same diagram we represent the relation between the 
density and concentration. We use the same vertical scale for dens- 
ity, 1.¢., from 1:00 to 1:30. The horizontal scale for the resistance- 
density curve is represented in ohms, each block representing 100 
-0) : 202 z : - 
+3 
| 
G) 





@ = Densily-Concenfration Curve 
© = Densily-Resis/ance Curve 
Fic. 2. 
ohms. The horizontal scale for the other curve, given at the top 
of the page, represents the difference between a theoretical density, 
calculated on the assumption that every molecule of salt added to 
the solution displaces one molecule of water, and the true density as 
observed with the pyknometer. Thus, if the theoretical density held, 
