POTASSIUM FERROCYANIDE. 



47 



No appreciable change was detected. The conductivities were measured 

 again after the solutions had stood for four hours, and still no change of 

 any moment manifested itself. The same result was obtained after the 

 solutions had stood for more than twenty-four hours. 



A change in the conductivity might have occurred before the first conduc- 

 tivity measurements were made. To test this, some of the salt was weighed 

 in the dry conductivity cup, and a known quantity of water, which had 

 already been brought to the temperature of the bath, added. In a very 



few minutes the first conductivity reading was 

 made. The conductivity did not change an ap- 

 preciable amount on allowing the solutions to 

 stand. 



It was then decided to determine whether there 

 is any change in the freezing-point lowering with 

 time. Fresh solutions were prepared and their 

 freezing-points determined immediately. These solutions were then allowed 

 to stand and their freezing-points determined from time to time. No change 

 could be detected. 



The value O///QO was then determined for potassium ferrocyanide, at 25, 

 with the result shown in the above table. 



The value of ,uoo seems to have been reached at a dilution of from 3,000 

 to 5,000 liters. 



DISSOCIATION OF POTASSIUM FEKROCYANIDE. 



The magnitude of this value throws some light on the question as to how 

 potassium ferrocyanide dissociates. It is almost exactly the value that 

 would have been obtained if potassium ferrocyanide dissociated thus: 



K 4 F e (CN) 6 = K,K,K,CN,CN,CN,K,F e (CN) 3 



TABLE 26. POTASSIUM FERROCYANIDE. 



