Section 108. The Conductivity Data. 305 



conceivably arise from a gradual leaching out of soluble impurities, but 

 this is disproved by experiments that will be described in the next section. 

 The method of heating and shaking just described was used in experi- 

 ments 1 to 5 (see table 129) with silver chloride and in all of those with 

 silver sulphocyanate. A slightly different procedure was followed in 

 some of the later experiments (6 to 9) with silver chloride and in those 

 with silver bromide, in that the bomb was removed from the bath after 

 the latter had reached about 99 and vigorously shaken before the first 

 bridge-reading was taken ; after which it was, as before, removed from 

 the bath, well shaken, returned to it, heated again for 30 to 60 minutes, 

 and a new reading taken. Even in this case the agitation took place 

 somewhat below 100, since the bomb cooled off a little, while it was out 

 of the bath ; but it is probable that enough fine particles remained in sus- 

 pension to secure saturation in the subsequent period of heating. In the 

 last two experiments with silver chloride (10 and 11) the bomb was not 

 shaken before the first reading at 100, but was heated for an unusually 

 long period of time (135 and 265 minutes, respectively) ; and afterwards 

 the effect of rocking the bomb gently in the bath was tried. 



108. THE CONDUCTIVITY DATA. 



The following table contains the results of the measurements. The 

 headings are for the most part self-explanatory. All the conductivity 

 values are those of the specific conductance expressed in reciprocal ohms 

 and multiplied by 10. The conductance of the water at 100 was cal- 

 culated, as stated above, from that at 46 by multiplying by 1.9. The 

 headings "first value'' and " second value" under "Specific conductance 

 of solution at t" will be understood from the description of the proce- 

 dure in the last section; the '"second value" was always that obtained 

 by removing the bomb from the bath after the "first value" was observed, 

 shaking it vigorously, and heating it again for a considerable period. In 

 the last column the time in minutes that the bomb was heated in the 

 100 bath before the reading for the "first value" was taken, is given 

 under I, and the time between the "first" and "second values" is given 

 under II. In the determinations with silver chloride the sample prepared 

 from silver nitrate and hydrochloric acid was used in experiments 4 and 

 5, that from silver nitrate and sodium chloride in all the others. In 

 experiments 6 to 9 the same portion of silver chloride was used, being 

 treated successively with fresh portions of water, to see whether the 

 apparent solubility would decrease owing to the leaching out at first of 

 more soluble impurities. 



