EFFICIENCY OF FOG CHAMBER. 



15 



irregular. The other data are much larger and as far as dp = 30 lie 

 sufficiently near together to show that limiting conditions are being 

 approached. Beyond this the curves diverge widely. The highest 

 results reached are those of May 30. On June 3 a change takes place 

 during the course of the experiment, as the result of which the incoming 

 and outgoing curves differ. In all cases there is a distinct tendency to 

 approach a limit after dp exceeds 37 cm., due to the limitations of 

 the apparatus. 



Figs. 8, 9, and 10. Early data of efficient nucleations (JV, n) and coronal diameter (s), 

 appearing at different exhaustions (dp) in dust-free air. Imperfect fog chamber. 



The characteristic feature of all the nucleation curves is the rapid 

 increase between dp = 27 and 30 cm.; that is, during the early coronal 

 stages. Below this the relatively large nuclei are present at least as far 

 as dp = 21 to the extent of a few thousand per cubic centimeter. Never- 

 theless, it is their variation which brings about the sinuous outline of 

 the curves above ^ = 33, seeing that large nuclei are overshadowingly 

 effective. 



