CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



the incidental data shown in table 34, obtained with fog particles about 

 0.0002 cm. in diameter, belonging to the large yellow -blue corona. 



TABLE 34. Contraction of coronas during subsidence. Bar. 75.2 cm.; temp. 27 C.; 



factor 1.56; temp, factor 0.027. 



The coronas shrink as the fog particles increase in number and de- 

 crease in size at an accelerated rate. The initial rates must be estimated 



at a decrement of number 

 greater than i . 4 per cent per 

 second, supposing that no 

 water is added from other 

 sources than the evaporation 

 of smaller particles. In 100 

 seconds about 80 particles 

 have escaped out of each 

 100. The case is much more 

 serious for larger coronas, so 

 that these are characteristic- 

 ally fleeting and must be ob- 

 served at once. It may not be 

 impossible that rapidity of 

 evaporation itself sets a limit 

 to the largest coronas pro- 

 ducible. The nuclei, however, 

 are not lost as a rule. They 

 occur as water nuclei and are 



ZOO 



Sec. 



zo 



40 



60 



80 



100 



FIG. 25. Nucleation n, computed from aperture 

 s of the coronas, gradually shrinking during 

 the subsidence within 100 seconds after ex- 

 haustion. 



available for the next coronas, if not removed. 



It follows, then, that for these cases the method of subsidence is not 

 applicable, as the corona changes totally before measurable subsidence 

 is recorded. Hence an instantaneous procedure like the goniometer 

 method or the present method is alone available. 



51. Data. In table 35 I have inserted results obtained with phos- 

 phorus nuclei, leaving out the initial fogs. It is seen at once that large 

 coronal diameters are actually measurable, a result not possible hitherto. 

 Reduced to the goniometer method, the present results may be written 

 0.12 5=5', for small coronas; but for large coronas, if 6 is the an- 



