328 THE EARL OF BERKELEY, MESSRS. E. G. J. HARTLEY AND J. STEPHENSON 



the concentration could be obtained from the graph of these two quantities which had 

 already been determined in the osmotic-pressure experiments. 



The water used for the dilution was distilled, in a Jena glass still, from a dilute 

 solution of potassium di-chromate, and its resistance determined in another cell to be 

 described later. 



The table on p. 329 is a copy of the Record of a typical experiment with calcium 

 ferrocyanide. 



The columns 1, 2, and 3, under the heading temperature, require a word of 

 explanation. The temperature under 1 is that of the solution just before the cell was 

 filled, 2 gives it just after the measurement of the resistance, and 3 just after 

 emptying. 



The solution contained '93023 gr. of anhydrous calcium ferrocyanide in 100 gr. of 

 solution. 



The ratio arms were 10 : 100 and the battery gave 2 volts. 



Resistance of the Solutions at Infinite Dilution. 



Although, as is well known, the relation between the conductivity at infinite 

 dilution and that at finite concentrations is not well established for salts of the 

 molecular complexity of the ferrocyanides, yet it was thought that this relation might 

 throw some light on the discrepancy indicated on p. 321. Experiments on very dilute 

 solutions were therefore undertaken. 



Low -resistance Cell. 



A cell for this purpose was kindly lent by Mr. WHETHAM ; it was made of Jena 

 glass and is shown in fig. 2. The electrodes D and E are coated with platinum 

 "grey" to prevent the absorption of salt, which, as pointed out by WHETHAM,* 

 generally takes place when platinum black is used. The cell was suspended in a 

 beaker of ice and water, and this in its turn was placed in ice. 



Make up of the Solutions. 



The water used was twice distilled in the ordinary way and then redistilled from 

 potassium di-chromate, the middle third only being used. All glass vessels and 

 pipettes were of Jena glass and the water and solutions were stored in stoppered Jena 

 glass flasks. 



Resistance Capacity of the Cell. 



The cell was standardised by means of a solution of potassium chloride containing 

 0'007352 gr. of salt in 100 gr. solution. This solution was obtained as follows: A 



* Loc. cit. 



