NOTES AND COOLTDGE. — ELECTRICAL CONDUCTIVITY. 195 



from that of the solution. Tliis at the same time corrects for contami- 

 nation, since, with a diUite, neutral-salt solution, there is no apparent 

 reason why the contamination should not be the same as for water. 

 For the dilutest solution used, 0.0005 normal, the maximum correction 

 (at 30G°) amounts to 1.9 per cent. See also Section XI. 



7. In the conductivity experiments, the vapor space at 140° and 218° 

 was considerable, so that at these temperatures a correction has to be 

 applied for the vaporized solvent, since the solution is more concentrated 

 than it would otherwise be. This correction was calculated from the 

 known volume of the vapor in the bomb and its specific volume, using 

 for the latter the data of Zeuner * which go up to 200°, and extrapo- 

 lating for the 218° value. The correction amounts to +0.05 per cent 

 at 140° and +0.18 per cent at 218°. As explained above, it is not 

 required in the case of the 281° and 306° values. 



8. The temperature measurement at 26° is certainly more accurate 

 than the work requires. Above this, the temperature reading is prob- 

 ably correct to 0.2°. Most of the uncertainty in the equivalent conduc- 

 tivity values introduced by this possible error finds expression in the 

 specific-volume values, and this has already been considered. Besides 

 this there is the much smaller effect on the observed resistance of the 

 bomb. The total uncertainty in the equivalent conductivity arises from 

 both these sources: that due to 0.2° is in the worst case (at 218°) 

 0.09 per cent, and where, as has usually been the case, several experi- 

 ments are made and the mean taken, this effect tends to be eliminated. 



IX. EXPERIJIENTAL DatA KELATIXG TO THE" SpECIFIC-VoLUME 



Determixations. 



All of the measurements have been included in Table I, with the ex- 

 ception of two, which, though agreeing well with the others, were known 

 to be less reliable. 



The first and second columns are self-explanatory. 



The third column gives the concentration of the solution at 4°, ex- 

 pressed in equivalents per liter. 



The fourth column gives the corrected temperature of the experiment. 



The fifth column gives the number of grams of solution which were 

 weighed into the dry bomb at the start. 



The sixth column gives the volume expressed in cubic centimeters, 

 which, at the temperature (135°) at which the bomb was calibrated, corre- 



* Landolt und Burnstein, Tabellen, 63 (1804). 



