EFFICIENCY OF FOG CHAMBER. 



17 



Table 7. Nucleation of dust-free, non-energized and energized air, different exhaus- 

 tions, dp. Lapse about 15 min. Barometer, 75.97 cm. Piping and stopcock of 

 1 -inch gas pipe. 



1 Vanishing at once and faint, only just visible. 



2 Nothing (fog or rain) observed. 



3 Accidental slow reopening: same result. 



* Exposure 2 minutes. No increment of N 



results. 

 1 All large wrg coronas. 

 Coronas clear but too small. 



7 Bottom of glass 1 cm. thick, interferes with for- 



mation of persistent nuclei even at short 

 distances like 25 cm. = D. 



8 Persistent nuclei just begin to be generated. 



a < 0.5 cm. maximum for fleeting nuclei. 



9 Next day. 



"Smaller than air coronas; a always taken. 



