Section gi. Errors and Corrections. 245 



91. DISCUSSION OF ERRORS AND CORRECTIONS. 



The errors inherent in the use of the conductivity bomb and the correc- 

 tions for them are fully discussed in section 10, Part II. A few additional 

 words in regard to the relation of them to the present work will suffice. 



In the earlier experiments with sulphuric acid made by Mr. Yogoro 

 Kato the bomb was always charged so as to have only from 1 to 2 

 c.cm. vapor-space at 218 and no correction for this was applied at any 

 temperature. The air pressure in the bomb was in all cases reduced to 

 3 or 4 cm. before the first measurement at 18. The bomb was usually 

 removed and shaken by hand at each temperature before the measurement 

 was made, as the rotating carriage had not at that time been introduced. 

 At 218 with the 0.0005 normal solution a considerable increase of con- 

 ductance always took place within one or two minutes after the current was 

 passed, but after this time no further change took place even in 15 

 minutes. The constant values resulting after the passage of the current 

 for 2 minutes or so are those given below in the table. This increase is 

 perhaps due to the throwing out of adsorbed substance from the elec- 

 trodes. With the 0.002 normal solution the effect was less regular and 

 far less pronounced. 



In our own experiments, the air was removed from the bomb only in 

 those extending to 218 or above, since its pressure at the lower tempera- 

 tures could not have a considerable effect. 



The correction for solvent in the vapor space was neglected below 

 218, as computation showed that under the prevailing conditions the cor- 

 rection was less than 0.02 per cent even at 156, where the vapor space 

 measured about 7 c.cm.; nor was this correction applied at 306, since 

 the vapor space amounted to only 2 to 3 c.cm. and since the specific volume 

 data used are affected by a corresponding error, which at any rate par- 

 tially eliminates the effect of the vaporization of the solvent on the values 

 of the equivalent conductance, as mentioned in section 10, Part II. At 

 218 whenever the vapor-space exceeded 2 to 3 c.cm. this correction was 

 made as there described. In the case of hydrochloric acid at 260 the 

 correction for vaporization of the solvent was combined with that for the 

 solute and was computed upon the basis of a direct experiment, which 

 will be now described. 



An estimate of the extent to which the solute volatilized was obtained 

 in the cases of nitric acid at 218 and of hydrochloric acid at 260 by 

 comparative experiments in which the bomb was charged with very dif- 

 ferent quantities of solution so that the vapor-space varied considerably ; 

 the difference in conductance was thus found in the case of nitric acid 

 at 218 to correspond to that which would have resulted from the vola- 



