A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



97 



than for the stopcock, there must be an accession of nuclei between the ex- 

 haustions in the former case or a loss of nuclei for the case of the plug. 



Between the middle g-b-p corona and dust-free air, nuclei are removed at 

 the same rate in the two cases, as the curves here have practically the same 

 slope and would be brought to coincidence throughout if the upper coronas 

 were to coincide. Inasmuch as in the case of atmospheric air the g-b-p corona 

 is not exceeded, it is thus immaterial which form of valve is used, and the direct 

 experiments of Chapter IX bear this out. 



The alternative that nuclei are generated by very sudden expansion is 

 without correlative evidence. At least all my experiments to detect ionization 

 produced by sudden expansion have failed. It is equally difficult to account 

 for an abnonral loss of nuclei in the earlier stages of the experiment of table i8. 

 True, it is here that the ionization of phosphorus vanishes, though this evan- 

 escence is enormously rapid by comparison. 



The nucleations of the g-b-p corona are by table i8, «= 129,000, 129,000, 

 and 145,000, respectively, values decidedly larger than were found above, and 

 due to the greater geometrical remove of the normal coronas from the g-b-p 

 corona. As about one more exhaustion is required on the average in the new 

 data, the coiTcsponding results for the same z would be, n = 94,000, 94,000, 

 106,000, which agi-ees with the order of values above. 



39. Different rates of exhaustion for moderate nucleations. — In this place it 

 is interesting to insert a series of direct comparisons on the ntunber of nuclei 

 within the reach of a half-inch exhaust pipe with an ordinary plug stopcock, 

 and the number caught when the valve is as iti figure 3 with all pipes over one 

 inch in diameter and less than one foot long. These are given in table 19, the 



TABLE 19.— DIRECT COMPARISON OF RESULTS FOR STOPCOCK .5" DIAMETER, 

 AND INSTANTANEOUS VALVE i" DIAMETER. LARGE CON- 

 DENSATION CHAMBER, AIR NUCLEI. Sp=i^ cm. 



