6 CONDENSATION OF VAPOR AS INDUCED BY NUCLEI AND IONS. 



atic method of investigation, though the effect of the precipitated 

 moisture (which has not yet been considered) will largely account for it. 

 (See section 9.) 



Anomalous relations in the data for the fog chamber, as in the case 

 of p' = S9-S cm -> are direct errors of observation. On the other hand, 

 however, since within the ranges of observation p = a, p 2 = a 2 + b 2 p', 

 p 3 = a 3 + b 3 p' very nearly.it follows that (pp^Kppz) mav approxi- 

 mately be written A + Bp', where a, b, A, B, etc., are constant. Fre- 

 quently B is negligible, so that (p 2 P^Kpps) is constant, in which 

 case the graphs for p 2 p 3 varying with p p 3 pass through the origin. 



4. Definite computation of p x and p 2 . If the adiabatic equations be 

 written without approximation 



TX P 

 the equations for p l and p 2 become 



*t~ fi*i-clk) I V 



V 1 



and 



PIXI (Pa-*) 



from which p v may be found after putting an approximate form for p^ 

 (p 3 nearly) into the vapor-pressure term of the second member. A 

 single approximation usually suffices. 

 From these equations 



__ 



. i- c /k 2 -- f d_ 



V\ V i 



follow at once. Subsidiary equations 



and 



PP' dp't 



v/V = - 



remain as before in section 3. To compute v/V in this way high ex- 

 haustion is essential, otherwise p' and p 3 differ but slightly. Between 

 the present group of equations, which are nearly rigorous, and the 

 preceding group the corrections to be added to the former may be 

 estimated. 



