Constants of Electrolytic Solutions. 835 



This assumes that the mutual inductance between the 

 transmitter and receiver is so small that variations in th« 

 current in the receiver do not appreciably affect the trans- 

 mitter current. If this condition is fulfilled, the graph 

 obtained by plotting C against C(I 2 /I 2 — 1)* is a straight 

 line passing through the point (Co, 0) ; the slope of this line 

 = K. Fig. 4 shows how these lines are affected by varying 

 the distance between the transmitter and receiver. 



III. Tests of the Formulae developed in the 



PRECEDING PARAGRAPHS. 



The circuits used in these tests (see fig. 3) had a com- 

 paratively large resistance, and consisted of a receiving- 

 inductance, two variable condensers in series, and a thermal 

 converter attached to a millivoltmeter. The capacity of one 

 condenser (Oj) was kept constant and approximately equal 

 to C during each set of readings. This symmetrical form 

 of circuit has the advantage that the voltage variation at 

 the centre of the thermal converter is a minimum, and there 

 is very little leakage of high-frequency current to the 

 galvanometer leads. 



The plates of the condenser x were two brass disks, the 

 distance between which could be varied by means of a 

 screw. In the following tables ?2 = the number of threads 

 by which the threads were separated. 



(a) Tests ivith distilled water. 



Water of various degrees of purity was used. The 

 wave-length in air was about 55 metres. In every case 

 K 2 (I 2 /i 2 — 1) was calculated (see equation 2) and found 

 to be negligibly smali. 



Table IV.— Distilled Water. 



x in uailliraicrofarads. 



11. 





A 





2 



0-3405 



0-2485 



0-3585 



3 



0-245 



0-23S 



4 



0-202 



0-192 



0-1865 



5 



0-152 



0-156 



01495 



G 



0-127 



0-131 



0-1275 



8 



0098 



0-100 



0-1015 



