Conductivity of External Solution. 
54 Stiles and J0rgensen . — Studies in Permeability . IV. 
it can be readily shown that there is a rough parallelism between the two. 
But the measurement of the electrical conductivity can be made much more 
accurately than colorimetric measurements. 
In the following experiment twenty discs of red beetroot, weighing 
altogether io grm., were placed in 50 c.c. of solutions of isoamyl alcohol 
(Kahlbaum) of various strengths. The conductivity was measured at 
various intervals of time and the colour intensity estimated. The colour 
intensity was compared with that of an extract obtained by boiling to grm. 
of beetroot with water and diluting down to 50 c.c. with slightly acid water. 
The following results were obtained, which are shown graphically in Fig. 2. 
Fig. 2 Exosmosis of electrolytes from beetroot in solutions of isoamyl alcohol of 
various concentrations. 
Ten grm. beetroot (twenty discs) in 50 c.c. 0*2 m. isoamyl alcohol. 
Time Conductivity. Colour. 
in hrs. and minutes (Sap extract = 900) (Sap extract = 1) 
0.15 120*8 0*5 
0.50 4 I2 ’4 i*o 
1.25 649*5 1*0 
1.55 766*0 1*0 
3-35 795’5 !*o 
19.15 782*0 1*0 
