30 A CONTINUOUS RECORD OF ATMOSPHERIC NUCLEATION. 



to about 30,000 nuclei, whereas those of the radial jet, No. 2, correspond 

 to io s or more. Hence weak ionization is to be expected, if the two occurrences 

 go in parallel. The table (part i) shows the positive and negative currents 

 when 8 liters of nucleated air pass through the condenser per minute. Hence 



for 2 lit./min. 



at + 80 volts, * = . 55X10"" amperes, 



at -- 81 volts, *' = . 25X10-" 



giving a mean current = . 40 X 10" ", as compared with 1.6 X io~" amperes for 

 the radial jet. Thus the mean current is about 4 times smaller, and the mean 

 nucleation also about 4 times smaller, as nearly as can be ascertained. There- 

 fore, the reduction of nucleation and of ionization run in parallel. 



For the flat -bottomed lead jet with 8 very fine needle holes, the ionization 

 was almost inappreciable. The current was about io~ 12 amperes, not much 

 exceeding the ordinary leakage of the electrometer. The corona was corre- 

 spondingly small. 



The next experiments, made with two capillary threads of water impinging 

 on each other (jet No. 7), are given in the third part of the table. The different 

 data for the mean current in case of a positive charge in the condenser and a 

 supply of 2 lit./min. of nucleated air passing through it show that i= .6X io~" 

 amperes. The coronas correspond to about 20,000 or 40,000 nuclei, evidencing 

 a relatively large ionization. 



The last experiments of the table were made with the large oblique jet 

 No. 3, and the coronas here obtained are just inferior to those of the radial jet, 

 corresponding to about 80,000 nuclei per cubic centimeter. The positive cur- 

 rents are about i= .7 X io~" amperes. When dV/dt = $, almost half the ions are 

 lost in transfer. 



Experiments were made at somewhat greater length with two oblique 

 capillary threads of water shattering each other, as in jet No. 3, above. Special 

 care was taken to prevent the jet from striking the walls of the vessel. As the 

 self -shattering was very complete, the spray reached the water with but little 

 churning. In spite of the small amount of water used, however, relatively 

 many nuclei were produced, the number estimated from coronas being 40,000 

 per cubic centimeter. 



Moreover, to keep the conditions more uniform, the water level in A , figure 

 i, was kept constant (efflux from k (Fig. i) being just as large as the water com- 

 ing from the spray) , and the nuclei were removed by a current of air flowing 

 through A into the condenser, C, at the rate of 2 liters per minute. The currents 

 so obtained are relatively large as compared with the number of nuclei, which is 

 due to the condition that the space in which the nuclei are produced is less than 

 ^ as large as usual above, and that therefore nuclei are fresher on entering the 

 condenser. The mean positive and negative currents were 

 at + 80 volts, *'=i.i X 10" " amperes, 

 at 80 volts, *'= .3 X io"" amperes, 

 the mean, .7 X io~" amperes, being about half as large as the currents for radial 



