44 CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



tion therefore varies in geometric progression with the number of ex- 

 haustions, apart from necessary corrections. The observations were 

 made in time series by two observers, Miss L. B. Joslin assisting me with 



FIG. ii. Fog chamber F, and vacuum chamber V. 



the work. Details will be given in connection with the data. The 

 initial isothermal (T) pressures p and p f of the fog and vacuum chambers 

 and the final isothermal (T) pressure p 3 , when in communication after 

 exhaustion, were carefully determined previous to the experiment with 

 coronas. These were needed for the computation of the amount of 

 water precipitated per cubic centimeter in each of the series of exhaus- 

 tions. In addition to this the pressure [^> 2 ] for finding the ratio of the 

 geometric sequence was necessary and found as follows: In each 

 exhaustion the stopcock was opened suddenly at the beginning of each 



