Section 10. Discussion of Errors and Corrections. 33 



(10) If the vapor above the solution had an appreciable conductance it 

 would make the conductance between the upper electrode and the bomb 

 appear too great. But this is not the case, as is shown by the fact that 

 unless the liquid is in contact with the electrode there is no measurable 

 conductance here, even at 306 with a 0.1 normal potassium chloride solu- 

 tion. We can at present assign only an upper limit to the conductance 

 of the vapor ; but it certainly does not exceed xottWo P ar t of that of the 

 solution. 



ERRORS AFFECTING THE CONDUCTANCE VALUES. 



(1) All the errors in the values of the specific volume have an effect of 

 the same magnitude upon those of the equivalent conductance, with the 

 important exception of that due to the amount of solvent in the vapor 

 space at the two highest temperatures, 281 and 306. No error arises 

 from this last source for the reason that, owing to the increase in concen- 

 tration of the solution, the specific conductance increases in the same pro- 

 portion as the volume diminishes; for at 281 and 306 (but not at 140 

 and 218) the quantity of liquid in the bomb was the same in the two 

 series of measurements. 



(2) The conductance-capacity might be expected to vary with the height 

 of the liquid level in the bomb, but direct experiment showed that for the 

 range of the liquid level in our measurements the effect of this was less 

 than the error of observation. The smallest amount of solution employed 

 in any of the experiments was first introduced into the bomb and the con- 

 ductance measured at 26. Then more of the same solution was intro- 

 duced until the liquid was in contact with the whole cover ; but the resist- 

 ance was not measurably changed. Mr. A. C. Melcher has shown (see 

 section 36, Part IV) that even much larger variations in the quantity of 

 solution have no effect. 



(3) The conductance-capacity changes with the temperature owing to 

 two causes : first, the expansion of the quartz-crystal cup ; and, secondly, 

 that of the bomb itself. A direct experimental investigation of the effect 

 on the conductance of such changes in the dimensions of the cup and bomb 

 has been made by Mr. A. C. Melcher and is described in section 36, Part 

 IV. The corrections for the conductance-capacity have been based on his 

 results. The relative values at the different temperatures are given in 

 section 13. 



(4) The effect of the pressure on the conductance-capacity is entirely 

 negligible. For at 306 the radius is increased by the pressure 0.01 per 

 cent, and this affects the conductance-capacity by even less. 



(5) The resistance of the lead-wires has to be deducted from the meas- 

 ured resistance of the bomb; and, since a portion of the leads is subjected 



