22 TITE STTirrTCTKE OF THE NUCLECS. 



particles generated i>er seeoiid per siipfirtcial square ceutim. of }>li()sphoriis, // 

 tbe nimiber per cubic ceiitim. of the ionized medium, k their velocity in any 

 cardinal <lirection, the variation of A' is to he ascribed to ii, k being relatively 



constant. 



In contrast with tiie color data (nuclei), the ionization of air passing over 

 phosphorus increases with temperature to a raaxiruuni at about 20°, after which 

 there is a less pronounced decline. This ionization is not an arrival comparable 

 in suddenness with the appearance of nuclei, nor are the maxima identical as to 

 tempeiature. One may infer that the nuclei as first produced are weak in 

 ionization but of normal strength in condensational activity, that thereafter the 

 latter property declines because (probably) the ionization increases as far as 20.° 

 Finally Iwth properties decline. This reciprocity is accounted for if the ionization 

 is a result of the dissociation of nuclei; but another explanation will follow in 

 Chapter VI, § 47 et seq. The degree of ionization found is here independent of the 

 sign of the chai'ge used in testing. 



If the phosphorus grid is not prelimiuai'ily quite dry, traces of moisture are 

 apt to escape with the emanation and pi'oduce permanent conduction in the con- 

 denser. Considerable variation of the electrical coefficients may thus ensue, though 

 the color lesults are, relatively speaking, but slightly affected. As the electi-ical 

 discrepancy seems to be out of proportion with the quantity of moisture present, 

 it is piobable that the emanation escapes in some combination with it. The 

 whole phenomenon vanishes on thorough desiccation both of the phosphorus and 

 the apparatus. Gi'ids frequently ti'eated in this way show a gradually decreasing 

 ionizing intensity, probably due to the continued consumption of phosphorus or to 

 a removal of effective suiface. Throughout the experiments the lelation of the 

 color curves to the electrical curves remains practically unchanged, in spite of 

 the different degrees of saturation (ionization). 



The relatively enormous conductions associated with non-desiccated phos- 

 phorus are without a color effect when tried in the steam tube. They rather 

 give evidence of an abstraction o{ nuclei. Moreover, such ieci[)rocal pioj.erties 

 are manifest in other instances, ^ 18. Air passed over damp paper behaves 

 similarly to the emanation from non-desiccated phosphorus, with a difference of 

 intensity in favor of the latter. Desiccation over calcic chloride removes the in- 

 cidental conduction entirely. The emanation may thus be dried to a limiting 

 degree of ionization which is not then further reduced on drying. In practice 

 all operations should be made with desiccated phosphorus; otherwise the baffling 

 discrepancies encouutei-ed in the case of plate and spherical condensers' may be 

 anticipated. 



By using freshly cut fuming phosphoius in excess in the ionizei-, it was possi- 

 ble to increase the radial currents in the condenser to nearly twice their usual 

 value, remembering that the emanation within the condenser is in all parts essen- 

 tially unsaturated. Hence the low concentrations formerly- found for tubular 

 conden.sers (8X 10* nuclei per cubic centim.), is tuade to approach the value found 

 from plate and spherical condensers more neaily. 



' Experiments un't/i Ionized Air, 1. c, Cliap. VI. ' Ibid., Chap. V. 



