24 CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



eye and lamp are at distances 30 and 250 cm. on opposite sides of the fog 

 chamber. The colors of the edge of the disk are denoted by r red, 

 v violet, g green, etc. The number of identical exhaustions made is equal 

 to z = 23. Beyond 2=13 the series was obtained twice with identical data. 



No attempt at computing nucleations from these data need be made, 

 as they are practically identical with the earlier series given in the pre- 

 ceding report. In fact, in fig. 3 the 5 values or apertures have been con- 

 structed in the curve a in terms of the number of the exhaustion z in the 

 geometric series. At b corresponding data (Carnegie Institution of Wash- 

 ington Publication No. 96, table 35, series i) are taken from the report 

 in question and represented in the same manner. 



The feature of these results which I wish to accentuate is this, that 

 after the tenth exhaustion, i. e., for small and moderately large coronas, 

 the s-data lie nearly on a straight line. In curve a this is the case almost 

 throughout, or at least until the coronas become so large as to be vague 

 and filmy, while the ends of the fog chamber interfere with the measure- 

 ments. The slopes of these lines are: 



In case a, ds/dz = 0.95 



In case b, ds/dz =0.95 



or about the same in both cases. 



25. Data with green mercury light, 10^ = 54.6 cm. Table 10 and figs. 

 4, 5, contain corresponding results obtained with a mercury arc lamp as 

 the source of light. Different annuli are measured and the chords 5, on 

 a radius of 30 cm. are distinguished by accents as follows : 

 5' is the chord of the green disk, 



s" is the chord of the inner edge of the first green ring, 

 s'" is the chord of the outer edge of the first green ring. 

 The edges are fairly sharp. Hence 



may be taken as the chord of the first green minimum. Optically the 

 diameter of the particle is then d' = 0.004/5. 



The water precipitated per cubic centimeter, in, differs with the drop 

 of pressure dp 3 / p and the temperature. Putting n' as the optical 

 value of the number of nuclei per cubic centimeter in the successive 

 seven parts of the tables the data are : 



