Section log. Conductance of the Saturated Solutions. 30/ 



109. FINAL CONDUCTANCE VALUES FOR THE SATURATED SOLUTIONS. 



Attention may be first called to the results with the two separate 

 samples of silver chloride. That prepared with hydrochloric acid and 

 used in experiments 4 and 5 gave the mean value 57.58 at 99.80 while 

 the sample made from sodium chloride gave 58.22 at 100.12. Reduced 

 to a common temperature of 100 by means of the temperature-coefficient 

 3.7 per cent per degree (see below) these values become 58.01 and 57.96, 

 which are in close agreement. 



It may be next pointed out that the four experiments (6-9) made suc- 

 cessively with the same portion of silver chloride do not show any pro- 

 gressive decrease, the values being 58.19, 57.82, 58.52, 58.87, thus making 

 it improbable that soluble impurities are enclosed within the solid salt 

 and are gradually leaching out. 



It is also of some interest to compare the mean value from experiments 

 1-5 with that from experiments 6-9, since in the latter, but not in the 

 former, the bomb was shaken after the temperature of the bath had been 

 nearly attained. These two mean values are 57.81 at 99.92, and 58.35 at 

 100.20, which when reduced to 100 become 57.98 and 57.92, respectively, 

 thus confirming the conclusion that saturation was attained in both series. 



It will be seen that the variable errors give rise to an average deviation 

 of the separate values from the mean conductivity of the salts of about 

 0.3 X 10~ 6 reciprocal ohms in all three cases. Far more serious, however, 

 are probably the constant errors, which may arise from the failure to 

 attain complete saturation in the "first values" at any rate, and from the 

 contamination of the solution by the progressive decomposition of the 

 salt. These two errors would affect the results in opposite directions. It 

 is, however, probable from what has been said above that the former 

 source of error is insignificant in comparison with the latter. The best 

 method of treatment seems to be, therefore, to apply a correction for the 

 progressive increase in conductance. Assuming that complete saturation 

 was attained in the case of the first values l x l w , then the increase 

 (l 2 l w ) (l x l w ) is wholly due to progressive contamination, and 

 assuming further that it is proportional to the time, we may obtain a better 

 value by subtracting from L t l w the product of this increase by the 

 ratio of the first period of heating* to the second period. In making 

 this calculation, the mean increase per hour was first computed for each 

 salt from all the experiments for which both "first" and "second values" 

 are given in the table.f Correcting in this way the mean of the first 



Decreased by ten minutes to allow for the time required to raise the bomb from 

 20 to 100. 



jThis was found to be 0.96 for AgCl, 0.84 for AgSCN, and 0.80 for AgBr. per 

 hour. Compare the values given in foot notes 1, 4, and 5 to table 129. 



