38 



T:\I>Ki;tMKNTS WITH IONIZED AIR. 



5. Woil-iiig hypothesis. — lu the eiKleavor to fi-ame at least a woi-kiiis^ h)-- 

 potliesis for tliese })henoiiiena, two jtossible occuiTeiice.s aie prominent: the tiist of 

 these is tlie decay uf the i)article so far as its activity in producing condensation is 

 concerned. This may be due to growth and loss of charge, to the action of ordinary 

 dust particles floating in the air, or any similar cause whatever. It constitutes a loss 

 wifhin the ionized medium itself. The second relates to the motion of the ionized 

 particle, whether stimulated by an electric field, or a diffusion gradient, or not, 

 occuiiiug in the latter case as a mere ionic velocity. Since electric field is absent. 



^% ^- I #K 



Fir.. 3. — Chart Showing the Relative Nu.mder of Particles (Ordi- 

 NATEs, Dust-Contents in Liters Per Minute) Needed to Produce Full 

 Blue for Different Lengths (Aiiscissas) and Diameters of the Ahsorption 

 Tubes. 



it would at the outset be natural to treat the motion as a case of diffusion and due 

 to a concentration gradient. It seems haidly piobable, however, that in a swift- 

 moving, turbulent current of aii', diffusion can be recognized. I have theiefore 

 thought it best to I'egard the nucleus as moving with a definite velocity /•, indepen- 

 dent of direction and (for a given class of experiments) independent of concentra- 

 tion. So circumstanced the swarm of nuclei are transferred by the air current. As 

 tlie nucleus impinges ujion but does not rebound from a bairier, I' may still be 

 regarded as an e.vtei-nal ditYusiou coefficient, corresponding to the constant in New- 

 ton's law of cooling. 



