The lonisation of Diktte SohUiom at the Freezing Point. 201 



stock solution was added to the solvent, as though the action took 

 time for its completion. While, however, in the case of permanganate 

 this phenomenon was only observed on adding the first lot of stock 

 solution, in the case of acid it appeared in the second solution also. 

 This confirms the idea that the action is not completed by the first 

 addition of acid, though the quantity of acid present must be large 

 compared "vvith the amount of residual impurity in the solvent. 



The permanganate measurements also show that the slant of the 

 curve is that of a salt like potassium chloride, with a monovalent acid 

 radicle, rather than that of a salt such as copper sulphate, with a 

 divalent acid. The chemical structure of permanganate in water 

 solution is therefore probably represented by the formula KMn04. 



The curve for potassium bichromate appears to consist of two parts, 

 an indication, perhaps, that the ions are diff'erent at different concen- 

 trations. 



In order to collect the results, smoothed values have been obtained 

 from the curves and are appended in Tables IX, X, XI, and XII. The 

 first three tables contain ionisation coefficients at 0°, the concentration 

 being tabulated in different ways. Table XII shows approximate 

 values for the equivalent conductivities at 0°. These were not neces- 

 sary for the determination of ionisation, so a single value of the cell 

 constant, obtained by comparison of the copper sulphate measurements 

 at 18° \nth Kohlrausch's absolute values, was used, except for the 

 potassium chloride solutions, which were reduced by a figure given by 

 Kohlrausch for this salt at 0°. The errors will be small, for the 

 amount of solvent left in the cell in each case was very nearly con- 

 stant, and this is a measure of the accuracy with which the cell is re- 

 adjusted after being taken to pieces. The results, however, are not 

 supposed to be as trustworthy as those of the ionisation coefiicients. 



