THE STUUCTIH:K of 'rilK NUCLEUS. 



'l'AB[,l': \.--C,uili,nicd. 

 II. 1 lalf-liour |ieriods. 



117 



III. Hour periods. 



' Veil, 30-35 cm. ' Open coronas, gradually more diffuse above, showing gradation. 



3 Veil, 40-50 cm. high. Frequent breakdown of stable distribution. 



10. HygromeWic discrepancy.— During the course of this woi'k on the diffu- 

 sion of nuclei in hydrocarbon vapors, I noticed that on certain days the experiments 

 were apt to bi-eak down ; the column of air within the tower-like i-eceiver, in.stead 

 of showing on exhaustion the sharp plane of demarcation between the nucleated 



