THE STRUCTUBE OF THE NUOLEIT.S. 



above the reaction temperature, the vapor pressure is i-ehitively constant as tem- 

 perature increases. All this recalls the well-known analogy appropriated by the 

 physical chemist. 



Now, if we suppose the nuclear velocity to be a relatively constant quantity, 

 within a short range of tempei'ature, while the emanating activity decreases, the 

 density of the emanation formed within the ionizer will clearly diminish as tem- 

 peratui'e decreases below the reaction temperature, however long the air is in contact 

 with the ionizer. 



Hence the color of the puffs should gradually become fainter with decreasing 

 temperatui'e, as actually observed. If iV^ nuclei are [)rodueed per su[)erficial S(piare 

 centim. of phosphorus, if h be the corresponding average nuclear velocity and n the 

 numbei' present per cubic centim., N = hi. Thus ?i<lepend8 on the ratio of yV and k. 

 The vapor pressui'e analogy suggested is not wholly tenable, inasmuch as niiclei are 

 actually absorbed at the walls of the vessel (tube ah, figure 1), so that A'^ vanishes 

 with II in the lapse of time. Since h is of the order of one unit, N and n may be 

 regarded as about of the same order, I'oughly speaking. The number of particles 

 generated per square centimeter of the phosphorus will not greatly differ from the 

 iuiml)er present per cubic centimeter of the emanation. 



6. Above the i-eaction temperature, if the rate of pi'oduction, N, were regarded 

 as relatively constant, the means of computing the increase of speed of the nucleus 

 with lising temperature would be at hand. If in be the mass of the nucleus and 

 mh^fi varies as absolute temperature, h^/k^^ — v\t^ + 273)/(i!j + 273). Tui'uing 

 now to the chart, figure 3, let t.^ — 30° and t^ = 20". Then k.^/k^ = 1.02, whereas 

 the chart gives k^Jk^ = 1.25. These two I'esults being out of keeping with each 



TABLE 2.— SUMMARY OF ADDITIONAL DATA FOR EFFECT OF TEMPERATURE 



ON THE PHOSPHORUS EMANATION. 



