90 PHYSICAL CHEMISTRY 



in wireless telegraphy. These oscillations induce similar ones 

 in the secondary coil, S, which is connected at one end with the 

 adjustable condenser, c, and at the other with the condenser, C, 

 between the plates of which the material to be investigated is 

 placed. The other plates of these condensers are connected, and 

 the circuit bridged by an instrument, n, for detecting a current, 

 according to the principle of the Wheatstone bridge. If the 

 capacity of c does not equal that of C some current will flow 

 through n. The plates of c are separated by such a distance that 

 no current flows through n, which means that the capacities of 

 c and C are equal. A test tube filled with the erythrocytes is 

 placed between the plates of C. If the capacity of C is thereby 

 increased, the plates of c would have to be approximated in order 

 that no current flow through n. In order to prevent error due 

 to the conductivity of the fluid wetting the outside of the cor- 

 puscles, they are washed repeatedly with isotonic sugar solution. 

 By filling capsules corresponding in size to the corpuscles with 

 solutions of different conductivity, and finding the conductivity 

 of the solution which causes the same increase in the capacity 

 of c as was caused by the blood corpuscles, the conductivity of 

 the interior of the corpuscles may be determined. Hober did 

 not make his capsules of conducting solutions as small as the 

 blood corpuscles nor consider the question of size at all. He 

 calculated that the conductivity of the interior of the corpuscles 

 is between that of a .1 and a .01 normal KOI solution. 



Fig. 26. Scheme for estimating the electric conductivity of cell in- 

 teriors by the damping of the inductance of a coil in the core of which 

 the cells are placed (from Hober, 1914). 



Another method for measuring the internal conductivity is the 

 damping method (Hober, 1915 b). In Fig. 26, S is the secondary 

 coil in which high frequency electric oscillations (io 7 a second) 



