THE STRUCTUHK 01'' THE NUCLEUS. 



87 



The veil at the l)ottom of the flask cU'ectiially resists removal, as may be inferred 

 from what has been stated. The first coronas are invariably full, strong, and 

 coarse. 



Tile nuclei siiaken out <>f the li<|uid arc reniarkaljly [)ersistent ; as, for example : 



Time elapsed after shaking, 

 20'" 

 3'' 20'" 



Exhaustion 1. 

 Intense fog and corona. 

 Corona, i- =.76, (/^.ook; 



1/2 corona, etc. 



In the last instance, the corona has coalesced with the coronas of spontaneous 

 nucleation, presently to be mentioned. In fact, the rise of coronas and their dif- 

 fusion may be tested by exhaustion in the way stated above. Thus, a (piartei" 

 corona will rise to a half corona in about lU minutes. 



26. S2wntaiieous nuclei. — The distinctive feature of these experiments is thus 

 the spontaneous production of nuclei in carbon disul})hide vapor, and a numl)er of 

 examples of these occurrences are summarized in the following table: 



TABLE 13.— SPONTANEOUS NUCLEI FROM CARBON DISULPHIDE. 

 PERFECT FILTER, CLEAR VESSEL. 



' Vessel in bright, warm, sunlit room : not in darkness, as usual. 



Though the large rilter and clean vessels wei'e used, it was not feasible to (piite 

 remove the sedimentary fogs by exhaustion. The rise of fog is at first filmy, and 

 never strong as a rule. After one or more hours, however, the corona stands out 

 full and coarse, and the graph shows that the diameter, s, of the corona, and with 

 it the number of pai'ticles per cubic centim., increases in the lapse of time to a limit. 

 Their diameter, d, decreases. 



When the vessel is left in a warm, sunlit room, i. e., when the evaporation is 

 accelerated in full daylight, the maximum spontaneous nucleation is reached in a 

 con-espondingly shortei' time, as the observation, a, of the corontd aperture shows. 

 These incidental ditiiculties are further indicated in the general iri'egularity of the 



