92 KXPERIMENTS WITH IONIZED All!. 



Sl'MMAKY. 



Willi tlie [ireseiil (.•li.-ipter 1 Inive given a systematic account oi tla- l)iilk. of 

 my Wink with tlie [ihosplioriis emanation, the purpose throughout being to map 

 out the plienomena in wliich I am interested, roughly and preliminarily to the 

 more rigorous study of the subject which I am now beginning. The results as a 

 whole are tributary to an investigation on the colors of chjudy condensation. 



In endeavorin<»- to account for the data (tbtained it was my endeavor to follow 

 the established theory, but I fear that in the explanations given I have little by 

 little made a serious departure. If I had obtained but a single coincidence the 

 result wotd<l not have been noteworthy ; but after finding data of a correct order of 

 values in all the experiments in spite of the variations of method, I have ventured 

 to think that more than a coincidence is in question. The theory which underlies 

 the series of papers is substantially this : 



(1) From experiments made in tlie absence of an electrical field I inferred 

 that the nucleus has its own specific velocity and that this velocity is identical 

 with the mutual velocity of the corres|)onding ions' in the unit electrical field 

 (volt/centim.). 



(2) The nucleus pi-oduced by phosphorus is larger than the air molecule and 

 both for this reason ami fi'om the fact that it receives promiscuous bombardment 

 of molecules simultaneously, its velocity is of the low order stated, being (say) less 

 than 1/300 that of the air molecule. 



(3) It is not necessary to assume that the nucleus decays or vanishes a\ ithin 

 the ionized medium; the evidence is rather in favor of a iiumbei' of nuclei some- 

 what larger as the dilution increases. 



(4) Whenever the nucleus coiues in contact with a barrier (solid or liquid) 

 it is absorl)ed or broken up. If the nucleus is ionized as in the case of the phos- 

 phorus emanation, the absorption is accompanied with the discharge of an 

 electron, as though the latter held the molecules of the nucleus together in a 

 cluster. 



(5) The observations with plate condensers, tubular condensers, and sjiherical 

 condensers are satisfied by supposing the nuclear velocity k to be indejiendent of 

 the concentration or degree of saturation, //. 



(6) The nuclear velocity is independent of the potential gradient. Instead 

 of putting I/. V / R for the velocity of the ion along the potential gradient V/R, I 

 have considered the velocity of the nucleus constant, and independent of V/R ; 

 while n, the number of nuclei capable of discharging the metallic terminal of a 

 field, varies as V/R. 



' Since the velocity of the |)ositive relative to the negative ions is understood, the nuclear 

 velocity is roughly taken to he three limes the absorption velocity, as in this case one third of all 

 the nuclei may approximately be sujiposed to travel in a given cardinal direction. It should be 

 noticed, however, that if instead of 3, the factor 6, or preferably the probability factor 16 /w be 

 taken, the statements of the text would be accentuated. For since ^ = -3 cm./sec, ^ X 16 / w = 

 1 . 5 cm. /sec, agreeing with the f/ of the text. 



