i6 



VAPOR NUCLEI AND IONS. 



On the 5th and 6th of August a series of experiments was made to test 

 the effect of long and short lapses of time between the observations, as 

 well as the displacements of lower limits of the curves. The results 

 of August 6 at dp*=3$ show that 15 minutes was an insufficient time 

 between observations, but that intervals exceeding 30 minutes (very 



100 



600 



500 



NxlO' 3 



Figs, ii, 12, 13, and 14. Early data of efficient nucleations (TV, n) and coronal diam- 

 eter (s), appearing at different exhaustions (<?/>) in dust-free air. Imperfect fog 

 chamber. 



slow filtration presupposed) are liable to show the true efficient nucle- 

 ation at the time of experiment. Direct experiments made under con- 

 ditions show that intervals of from one to two hours will in all cases 

 be sufficient for the decay of extraneous nuclei. 



