CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



The series of variables given in table i, where p denotes pressure, 

 p density, r absolute temperature, TI vapor pressure, is to be considered. 

 The ratio of volumes of the fog and vacuum chambers was about 

 v/V = 0.064. 



TABLE i. Notation. Drop of pressure op = p p 3 , observed; 8p = p p v computed. 



At the beginning (case i), the fog chamber is at atmospheric pressure 

 p (nearly), the vacuum chamber at the low pressure p', and both at 

 the absolute temperature T. On suddenly opening the stopcock the 

 adiabatic pressures, etc., given under No. 2 appear, supposing that no 

 condensation has yet taken place in the fog chamber. If the stopcock 

 could now be suddenly closed and the whole apparatus allowed to 

 regain the original temperature T, the conditions under No. 4 would 

 obtain. This is virtually the case in Wilson's* piston apparatus, 

 and consequently these variables are comparable with his results 

 (cf. sections 3 and 4). In my apparatus, however, condensation takes 

 place within the fog chamber before the stopcock can be closed, and 

 thus an additional quantity of air is discharged from the fog chamber 

 into the vacuum chamber. After condensation and before the stopcock 

 is closed the conditions under No. 3 apply; when the stopcock has been 

 closed and the apparatus allowed to regain the room temperature T, 

 the conditions are shown in No. 5, and may be observed with crude 



*C. T. R. Wilson: Phil. Trans., London, vol. 1992, 1889, pp. 405 et seq. 



