328 ON THE CALCULATION OF THE CONDUCTIVITY OF 



copper wire. In order to draw the correction curve more 

 accurately, the wire was calibrated by this means in a number 

 of different fractions. The possible error of a conductivity 

 measurement, when the reading was made at the middle of the 

 bridge wire, was shown by a number of determinations to be 

 about one-tenth of one per cent. For solutions of BaCl 2 and 

 NaCl measured in the cell first described, the reading would be 

 made at this part of the wire if the concentration was about 0.3 

 gramme-equivalent. For 0.5 gramme-equivalent solutions, with 

 the reading at or near .64 of the length of the bridge, two-tenths 

 per cent, for normal solutions four-tenths. With the cell for 

 dilute solutions, the possible error, wherever the reading might 

 be made, was about six-tenths. Here other sources of error, 

 such as change of capacity of the cell, were greater than the 

 bridge error. In order to obtain a good minimum also a high 

 clear note from the induction coil was necessary when a very 

 dilute solution was in the cell, and this could not always be 

 obtained. 



The capacity of each cell was determined by a comparison of 

 the conductivities of the solutions measured in it, with the values 

 given for corresponding solutions by Kohlrausch. The numbers 

 given below, under the headings NaCl and BaCl 2 are the ratios 

 of the conductivities of solutions measured in the first cell, to the 

 specific conductivities of corresponding solutions, as measured 

 by Kohlrausch. 



