9 6 



CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



TABLE 41. Sizes of water nuclei. Radium ionizer. Slightly open filter cock; 



t several minutes. 



'Radium not removed. 2 Cock open late. 3 gbp. 4 wo. 6 gyo. 



'Subsequent exhaustion to catch the water nuclei left after first exhaustion, we to gbp, very faint. 

 8 gbp. 



The data are given in fig. 30, n in terms of the relative drop in pressure, 

 x = dp a /p. Though the experiments were made with great care and 

 apparently satisfactory, the results are disappointing; but this is prob- 

 ably to be expected when the water nuclei are only obtainable by 

 evaporations lasting as much as a fraction of a minute, during which 

 there must be both subsidence and probably also a washing-out of 

 nuclei by the disturbance produced during the influx of air. In the first 

 series, where there are 115,000 ions, not more than 30,000 or 40,000 water 

 nuclei (about one-third), are obtainable. On opening the filter cock 



