3 o8 



Conductivity of Aqueous Solutions. Part X. 



values in the table we get the following final results, which have also 

 been corrected to 100 with the help of the van't Hoff equation* and the 

 temperature-coefficient of the conductivity of silver nitrate.f 



Table 130. Specific conductance of the satu- 

 rated solutions at ioo. 



It seems very improbable that the errors from any source in these final 

 values exceed half the differences between them and the ''first values" 

 directly observed. Under this assumption the possible percentage errors 

 are 1.2 for the chloride, 2.9 for the sulphocyanate, and 4.0 for the bromide. 



110. THE SOLUBILITY VALUES. 



To derive the solubility (in equivalents per cubic centimeter) from 

 these conductance values, it is necessary to divide them by the equivalent 

 conductance (A ) of the salt at zero concentration and at 100. The A 

 value for silver nitrate at 100 has already been determined to be 367 by 

 Mr. A. C. Melcher; and since those for the three silver salts in question 

 are known to differ from this by only 3 to 4^4 per cent at 20$, and 

 the differences between the mobilities of various ions become less with 

 rising temperature, no error of importance will be made by assuming 

 the A -values for the three salts to differ from that for the nitrate at 100 

 by half the percentage amount by which they differ from it at 20. The 

 A -values at 100 calculated under this assumption are 373 for AgCl, 359 

 for AgSCN, and 375 for AgBr. 



The solubility values at 100 computed in this way and expressed in 

 milligrams and in equivalents per liter are given in the following table. 

 For comparison the values previously found at 20 and the ratio of the 



dS/S L 



, where .S is the solubility and L the molal heat of solution, whose 



2 rl 9 / <T 



values are cited in the next section. is thus found to be at 100 2.8 per cent for 



AgCl, 4.0 per cent for AgSCN, and 3.6 per cent for AgBr. 



fThis temperature-coefficient has been found by Mr. A. C. Melcher to be 0.88 

 per cent at 100. Combining this with the temperature-coefficient of the solubility, 

 we get for the temperature-coefficient of the conductance of the saturated solutions 

 3.7 per cent for AgCl, 4.9 per cent for AgSCN, and 4.5 per cent for AgBr. 



tSee Bottger, Zstchr. phys. Chem., 46, 596 (1903). The values at 20 are 121.7 

 for AgNOs, 125.5 for AgCl, 127.1 for AgBr, and 116.1 for AgSCN. Those for the 

 three latter salts differ from that for the nitrate by +3.1-1-4.4, and 4.6 per cent, 

 respectively. 



