NUCLEI OF PURE WATER. 



TABLE i. Quick evaporation. (Reproduced from Carnegie Institution of Washington 

 Publication No. 92, chap, in, table 17, 1908.) y = o- 



SERIES A. 



3. Spontaneous evaporation of fog particles. Phosphorus nuclei. With 

 the above data one may now compare the corresponding cases for very 

 slow evaporation, in which the fog has disappeared spontaneously in the 

 lapse of time, apparently by subsidence, but in greater measure by 

 evaporation. Part i of table 2 shows the results obtained in a very long 

 (2 meters) brass tube, lined with wet cloth but 4 cm. high and broad. 

 Tw r elve exhaustions are needed for removing the nucleation, in spite of 

 the spontaneous disappearance of each individual fog. The disappointing 

 feature about these experiments with 2 -inch tubes is the total absence of 

 disk or axial color throughout. They were made in the hope that such 

 colors would appear. 



In parts 2 and 3 of the table these observations are continued, but now, 

 with a glass fog chamber, where the line of vision passes through but 8 cm. 

 of fog as compared with 200 cm. above. The exhaustion ratio is ^ = 0.78, 

 as in table i . Besides the disk color of coronas, the successive nucleations 

 n and the nucleation ratios n'/n are given. These ratios are also con- 

 structed in fig. i in terms of n, in the curves 2 and 3 of the chart. Not- 

 withstanding the complete apparent subsidence, nine exhaustions are 

 needed to clean the fog chamber of these solutional nuclei ; but the effect 

 of subsidence is here unmistakable at least below n= io 6 nuclei per cubic 

 centimeter. From a smooth curve, embodying series 2 and 3, the sub- 

 sidence effect, together with other permanent loss, may be stated as 

 follows (y o.'jS). The approximate diameter is d. 



