8 
It will be noticed that the straight line portion of the curve, 
when produced, cuts the conductivity axis at a point B, which is) 
below the starting point A. The portion AB represents what we 
may call the ‘loss of conductivity, the net result of the initial 
Messrs Paine and Evans, The Conductivity of ' 
irregularity in the simple conductivity curve. 
Table II is a summary of the observations made with four 
specimens of distilled water. The units are the same as before. | 
TABLE II. 
Lower concen- 
ue : : ‘Loss of Con- dk/dm 
No. of | Initial conduec- | tration at which Fis 
a ae : : ductivity’=AB | the tangent of 
Series | tivity of water eee He be in Fig. 4 ine strat line 
1 0°61 x 10-8 1:0 x 10 12x10 0:369 
2 0:64 x 10-5 ere 36 102 Oo7/ 32 IO=2 362 
3 0:36 x 10-8 O-ecalOm 0-8 x 10-° *355 
4 0:53 x 10-8 0:8 x 10-5 0:5 x 10-8 364 
Mean 0:362 
IV. 
Let us now examine these results in the light of the hypothesis | 
mentioned in the first section of this paper, dealing in turn with | 
the last three columns of Table II. : 
(1) In the first place it will be seen that the straight line | | 
persists for concentrations a little smaller than the smallest of | 
those examined by Kohlrausch (10~ gm.-equiv. per litre). 
That | 
is to say, the irregularities cease when the quantity of acid added 
amounts to about 0:8 x 10~* gm.-equiv. per litre, the residual 
impurities of the distilled water being then ‘neutralised’ — 
(2) Again, a comparison of the numbers in columns 2 and 4 
of Table II will show that the ‘loss of conductivity’ in any case 
is generally greater than the initial conductivity of the water. 
This is interesting, for it is the easiest way of seeing that the - 
presence of carbonic acid alone could not, as a rule, account for the — 
initial irregularities. 
acid through the addition of a strong acid. 
For any loss of conductivity that occurred — 
would be due simply to the association of this (ionised) carboni¢e 
Consequently the 
maximum loss of conductivity could not be greater than the 
initial conductivity of the solvent. a 
alkali or a carbonate, say ammonium carbonate, as the residual 
On the other hand, with an 
ea! 
