62 NUCLEATION OF THE UNCONTAMINATED ATMOSPHERE. 



The data of table 37 were at first obtained in the wooden fog chamber. 

 It was thought advisable to repeat them with the cylindrical glass fog 

 chamber, as this could be kept rigorously free from leakage (curves 

 58, 59). The mean results show that about 20 per cent of the particles 

 persist indefinitely. This datum, which in any case is an inferior 

 limit, is smaller here, because the amount of subsidence is relatively 

 greater in a more shallow vessel. Without condensation, i. <?., in the 

 absence of solution , only 2 to 5 per cent of the nuclei persist after 

 i minute. With solution, the decay is not appreciably different in i 

 to 3 minutes, showing that long periods of persistence are in question. 



60 



O&tehvattcn JUa- 



FIGS. 56-62. Illustrating tables 37, 38. 



Tab. 10 in the above chart is replaced by the present table 37 ; Tab. n, by the present table 38. 



50. Enlargement of nuclei in dust-free nonenergized air. An exceed- 

 ingly interesting correlative result is obtained by converting the nuclei 

 of dust-free nonenergized air into solutional nuclei. Here the first 

 exhaustion must necessarily be made at a pressure difference (say 



