1907.] 



BARUS— NUCLEI IN DUST-FREE WET AIR. 



73 



to 10^ vapor nuclei per cubic centimeter as he asserts. Compare 

 section 5. 



5. Distribution of Vapor A'uclei and of Ions in Dust-free Air. — 

 On r^Iarch second the author gave a resume of certain typical re- 

 sults to the American Physical Society. Distributions were there 

 given in terms of an unsatisfactory expansion • variable, 

 (Sp — (tt — 'n-i))/(p — tt), involving vapor pressure, w, as well as 

 the drop in pressure, Bp, from the atmospheric pressure p. In the 

 present graphs these results and the new data specified will be given 

 in terms of the relative adiabatic drop Bp/p, as a more appropriate 



•C^je^ 1 19 no I!' 



Figs. 2 and 3. Distribution of nucleation (n nuclei per cubic cm.) for 

 different drops of pressure Sp adiabatically from p, or volume expansion 

 z'l/'Z^. Series III to X were found with dust free air not energised at dif- 

 ferent times and temperatures. D^ refers to the distance of the radiant tube 

 or X-ray bulb from the fog chamber. T and T' show the results of J. J. 

 Thomson. IV refers to Wilson's fog limits, B to those of the writer. Fig- 

 ure 2 is an enlarged detail of figure 3 refering in particular to the regions 

 of ions. 



variable for the plug-cock fog chamber. The adiabatic volume 

 expansion is then 



(:'^/z')y =1/(1- Sp/p), 



